阅读说明：本技术 一种高效光电极及其制备方法与应用 (High-efficiency photoelectrode and preparation method and application thereof ) 是由 胡宗倩 李刚勇 于 2021-07-23 设计创作，主要内容包括：本发明公开了一种高效光电极及其制备方法与应用。所述光阳极的制备方法包括如下步骤：采用线性扫描伏安法,在AM 1.5G光照下,采用光电沉积法在Bi-(2)O-(3)-BiVO-(4)光阳极上制备NiFeO-(x),即得到NiFeO-(x)/Bi-(2)O-(3)-BiVO-(4)光阳极；将Fe(SO-(4))-(2)·7H-(2)O或FeCl-(2)·4H-(2)O和Ni(SO-(4))-(2)·6H-(2)O或NiCl-(2)·6H-(2)O溶解于硼酸盐缓冲液中,然后进行光电沉积。本发明通过将Bi-(2)O-(3)-BiVO-(4)异质结与NiFeOx助催化剂的配对,进一步提高了BiVO-(4)的光催化性能,可以与葡萄糖脱氢酶功能化的生物阳极组成的空间分离的混合阳极,以及胆红素氧化酶修饰的生物阴极集成于BPEC中,全天候地从光和生物燃料发电。(The invention discloses a high-efficiency photoelectrode and a preparation method and application thereof. The preparation method of the photo-anode comprises the following steps: adopting linear sweep voltammetry, and adopting a photoelectric deposition method to deposit Bi under the illumination of AM 1.5G 2 O 3 ‑BiVO 4 Preparation of NiFeO on photo-anode x To obtain NiFeO x /Bi 2 O 3 ‑BiVO 4 A photo-anode; mixing Fe (SO) 4 ) 2 ·7H 2 O or FeCl 2 ·4H 2 O and Ni (SO) 4 ) 2 ·6H 2 O or NiCl 2 ·6H 2 O is dissolved in borate buffer and then subjected to photoelectric deposition. The invention is prepared by mixing Bi 2 O 3 ‑BiVO 4 The pairing of the heterojunction and the NiFeOx cocatalyst further improves the BiVO 4 Photocatalytic property of (A) canA spatially separated hybrid anode consisting of a glucose dehydrogenase functionalized bioanode and a bilirubin oxidase modified biocathode are integrated in BPEC to generate electricity from light and biofuels around the clock.)

1. A preparation method of a photo-anode comprises the following steps:

adopting linear sweep voltammetry, and adopting a photoelectric deposition method to deposit Bi under the illumination of AM 1.5G₂O₃-BiVO₄Preparation of NiFeO on photo-anode_xTo obtain NiFeO_x/Bi₂O₃-BiVO₄And a photo-anode.

2. The method of claim 1, wherein: mixing Fe (SO)₄)₂·7H₂O or FeCl₂·4H₂O and Ni (SO)₄)₂·6H₂O or NiCl₂·6H₂O is dissolved in borate buffer and then subjected to photoelectric deposition.

3. The method of claim 2, wherein: the molar concentration of the borate buffer solution is 0.1-0.5M, and the pH value is 8.0-8.5;

said Fe (SO)₄)₂·7H₂The concentration of O is 0.05-0.2 mg mL^-1；

The Ni (SO)₄)₂·6H₂The concentration of O is 0.01-0.04 mg mL^-1。

4. The production method according to claim 2 or 3, characterized in that: the conditions of the linear sweep voltammetry were as follows:

taking Ag/AgCl as a reference electrode and Pt foil as a counter electrode;

LSV tests were performed for different periods over a potential range of-0.4V to 0.6V until the LSV curves overlapped.

5. The production method according to any one of claims 1 to 4, characterized in that: the Bi₂O₃-BiVO₄The photoanode was prepared as follows:

dropping the solution of vanadium acetylacetonate in Bi₂O₃Bi of/TCO conductive glass₂O₃And calcining the film in the air to obtain the catalyst.

6. The method of claim 5, wherein: in the solution of vanadium acetylacetonate, the concentration of vanadium acetylacetonate is 100-300 mM;

the calcining temperature is 400-500 ℃, and the time is 1-3 h.

7. The production method according to claim 5 or 6, characterized in that: the method further comprises the steps of:

and after calcination, naturally cooling to room temperature, and then soaking in NaOH solution.

8. NiFeO produced by the method of any one of claims 1 to 7_x/Bi₂O₃-BiVO₄And a photo-anode.

9. N as recited in claim 8iFeO_x/Bi₂O₃-BiVO₄The application of the photo-anode in the construction of a biophotonic electrochemical cell.

10. The use according to claim 9, characterized in that: the biological anode of the biological photoelectrochemical cell is a GDH/1,4-NQ/CNTs biological anode.

Technical Field

The invention relates to a high-efficiency photoelectrode and a preparation method and application thereof, belonging to the technical field of photoelectrocatalysis.

Background

With the concern of the increasing exhaustion of non-renewable fossil fuels and the growing environmental problems, it has become an important hot spot of current research to obtain energy from renewable resources in an efficient and environmentally friendly manner. The electric power generated from non-renewable resources such as coal, oil and natural gas at present means the futureThe power system may be primarily derived from sustainable and renewable resources such as solar energy and chemical energy of biomass energy. Solar energy is considered to be the ultimate renewable resource that we can harvest on earth, so that obtaining electric energy from solar energy provides a sustainable approach for the development of renewable energy sources. Among various solar energy conversion technologies, the photoelectrochemical cell is an effective way to utilize a photoelectrode to absorb solar photons, separate photo-generated charge carriers, and directly convert solar energy into electric energy and chemical fuel for photocatalytic water decomposition, pollutant or CO degradation₂And (4) reducing. However, due to the intermittent nature of the sun caused by weather conditions and/or autorotation of the earth, the continuous energy demand in actual production is limited and the electrical energy produced therefore needs to be stored in rechargeable batteries or capacitors before use, which further increases the cost, complexity of the system and energy losses.

An enzymatic biofuel cell (EBFC) is an energy conversion device that directly converts chemical energy in biomass into electrical energy through bioelectrocatalytic reaction using partial catalytic activity of an oxidoreductase, and receives increasing attention due to advantages of mild operating conditions, environmental friendliness, high catalytic efficiency, selectivity to specific reactants, and the like. However, since the energy conversion pathway of EBFC is unidirectional (chemical energy to electrical energy), further improvement of its performance remains a challenge. The solar energy collector is integrated into the EBFC, a bidirectional conversion path from solar energy and chemical energy to electric energy is constructed, and the EBFC is a possible alternative scheme for realizing higher energy conversion efficiency and meeting all-weather energy requirements in actual production.

In recent years, interest in solar/chemical energy conversion has driven the development of new types of electrical energy collection systems. The biological photoelectrochemical cell (BPEC) consists of two parts of bioelectrocatalysis and photoelectrocatalysis, is an ideal system for simultaneously converting light energy and chemical energy into electric energy, and has the biocompatibility of EBFC and the robustness of photoelectrochemical cells (PECs). In the design of photoanodes, photosystem II (PSII) is commonly used as a biocatalyst, catalyzing H under illumination₂Oxidation of O, thereby liberating 4H⁺、4e^-And O₂. When coupled with a cathode to catalyze the reduction of H⁺Or O₂When the solar energy is converted into hydrogen or electricity, the conversion of the solar energy into the hydrogen or the solar energy into the electricity can be realized. For example, an integrated BPEC consisting of a PSII-modified photoanode and a Bilirubin Oxidase (BOD) -functionalized biocathode has been reported. However, the low surface coverage, low charge transfer efficiency and large amount of potential losses of PSII still limit the performance of the battery. In contrast, inorganic semiconductor photoanodes with low catalytic potential, high carrier mobility and appropriate light absorbing band gap have been the hot research for solar energy conversion. For example, with MoS₃BPEC is prepared from the modified Si nanowire photocathode and the microbial-catalyzed biological anode, and can be used for hydrogen production and power generation. Zhang et al reported a Ni FeOOH/BiVO₄BPEC consisting of a photoanode and a laccase functionalized biocathode. The resulting BPEC had an Open Circuit Potential (OCP) of 0.97V and a maximum power density at illumination of 205. mu.W cm^-2. Recently, BiFeO modified by glucose oxidase has been reported₃Photobiocathodes and Flavin Adenine Dinucleotide (FAD) -dependent Glucose Dehydrogenase (GDH) functionalized and quantum dot sensitized TiO₂Tandem BPEC prepared by photo-biological anode, the system generates high OCP of about 1V in the presence of illumination and glucose, and simultaneously realizes the conversion of light/chemical energy into electric energy. However, due to the complex enzyme/semiconductor interface and limited cathode reaction, tandem BPEC produced 23.9. + -. 3.5. mu.A cm^-2Photocurrent of 8.1. + -. 1.1. mu.W cm^-2The maximum power density of. Despite the advances made in these systems for generating photocurrent, to date, no integrated BPEC has been able to generate satisfactory electrical power under either irradiation or dark conditions.

Disclosure of Invention

The invention aims to provide a high-efficiency photo-anode, namely NiFeO_x/Bi₂O₃-BiVO₄Photoanode by adding Bi₂O₃-BiVO₄The pairing of the heterojunction and the NiFeOx cocatalyst further improves the BiVO₄The mixed anode can be spatially separated from the glucose dehydrogenase functionalized biological anode, and the bilirubin oxidase is modifiedDecorated biocathodes are integrated in BPECs, generating electricity from light and biofuels around the clock.

The preparation method of the photo-anode provided by the invention comprises the following steps:

adopting linear sweep voltammetry, and adopting a photoelectric deposition method to deposit Bi under the illumination of AM 1.5G₂O₃-BiVO₄Preparation of NiFeO on photocathode_xTo obtain NiFeO_x/Bi₂O₃-BiVO₄And a photo-anode.

In the above preparation method, Fe (SO)₄)₂·7H₂O or FeCl₂·4H₂O and Ni (SO)₄)₂·6H₂O or NiCl₂·6H₂O is dissolved in borate buffer and then subjected to photoelectric deposition.

In the preparation method, the molar concentration of the borate buffer solution is 0.1-0.5M, and the pH value is 8.0-8.5;

said Fe (SO)₄)₂·7H₂O or said FeCl₂·4H₂The concentration of O is 0.05-0.2 mg mL^-1；

The Ni (SO)₄)₂·6H₂O or said NiCl₂·6H₂The concentration of O is 0.01-0.04 mg mL^-1。

Specifically, the conditions of the linear sweep voltammetry are as follows:

taking Ag/AgCl as a reference electrode and Pt foil as a counter electrode;

LSV tests were performed for different periods over a potential range of-0.4V to 0.6V until the LSV curves overlapped.

Preferably, the Bi₂O₃-BiVO₄The photoanode was prepared as follows:

dropping the solution of vanadium acetylacetonate in Bi₂O₃Bi of/TCO conductive glass₂O₃Calcining on the membrane in the air;

in the solution of vanadium acetylacetonate, the concentration of vanadium acetylacetonate is 100-300 mM;

the calcining temperature is 400-500 ℃, and the time is 1-3 h.

The method further comprises the steps of:

and after calcination, naturally cooling to room temperature, and then soaking in NaOH solution.

The invention passes through Bi₂O₃-BiVO₄The construction of heterojunction and the pairing with NiFeOx cocatalyst improve BiVO₄The photoelectrocatalysis performance of the base light anode.

The photoanode with high photocatalytic activity provided by the invention is combined with a GDH functionalized bioanode capable of catalyzing glucose oxidation under the condition of light or dark, and the biological/photocatalytic glucose oxidation generates electrons which are transferred from the anode to a BOD modified biocathode through an external circuit for O₂Reduction to H₂O, to achieve a sustainable power output under irradiation or dark conditions; in the constructed biological photoelectrochemical cell, GDH/1,4-NQ/CNTs biological anode and NiFeO_x/Bi₂O₃-BiVO₄The spatially separated arrangement of the photoanodes not only avoids deactivation by direct contact of the enzyme and the semiconductor, but also produces ordered and more efficient electron transfer, thereby enhancing compatibility between the PEC and EBFC and minimizing energy loss during operation.

The biological photoelectrochemical cell constructed by the photo-anode of the invention generates electricity in all weather by light and biological fuel conversion, and the maximum power output density is 1.76mW cm^-2OCP was 0.83V under AM 1.5G illumination, 0.78V under dark conditions, and maximum output power density was 1.3mW cm^-2Provides a new approach for the integration of photoelectrocatalysis and bioelectrocatalysis elements for generating electricity by light and biofuel.

Drawings

FIG. 1 shows BiOI/FTO (FIG. 1(a)) and Bi prepared in example 1 of the present invention₂O₃XRD pattern of/FTO (FIG. 1 (b)).

FIG. 2 shows BiVO prepared in example 1 of the present invention₄/FTO、Bi₂O₃-BiVO₄FTO and NiFeO_x/Bi₂O₃-BiVO₄XRD pattern of/FTO.

FIG. 3 shows BiOI/FTO (FIG. 3(a)), BiVO prepared in example 1 of the present invention₄FTO (FIG. 3(b)), Bi₂O₃-BiVO₄(FIG. 3(c)) and NiFeO_x/Bi₂O₃-BiVO₄SEM image of/FTO (FIG. 3 (d)).

FIG. 4 is a TEM characterization of the material prepared in example 1 of the present invention, wherein FIGS. 4(a) -4 (b) are BiOI and Bi, respectively₂O₃-BiVO₄And NiFeO_x/Bi₂O₃-BiVO₄In FIGS. 4(d) to 4(f), the TEM images of (A) and (B) are BiOI and Bi, respectively₂O₃-BiVO₄And NiFeO_x/Bi₂O₃-BiVO₄HRTEM image of (the inset shows NiFeO)_x/Bi₂O₃-BiVO₄FFT images in different regions), fig. 4(g) for NiFeO_x/Bi₂O₃-BiVO₄And the corresponding STEM-EDS element mapping images of Bi, V, O, Ni and Fe.

FIG. 5 shows the results of elemental analyses of the materials prepared in example 1 of the present invention, wherein BiVO is shown in FIGS. 5(a) to 5(d)₄/FTO、Bi₂O₃-BiVO₄FTO and NiFeO_x/Bi₂O₃-BiVO₄Broad XPS spectra of/FTO, Bi 4f, V2 p and O1s XPS spectra, FIGS. 5(e) -5 (f) for NiFeO respectively_x/Bi₂O₃-BiVO₄XPS spectra of Fe 2p and Ni 2p for/FTO.

FIG. 6 is an electrochemical performance of an electrode prepared according to an example of the present invention, wherein FIG. 6(a) is 10mV s in 0.1M PBS (pH7.0) containing 500mM glucose^-1Sweep speed record BiVO₄、Bi₂O₃-BiVO₄And NiFeO_x/Bi₂O₃-BiVO₄The LSV curve of (a); FIG. 6(b) is BiVO in 0.1M PBS (pH7.0) containing 500mM glucose under AM 1.5G chopping light₄、Bi₂O₃-BiVO₄And NiFeO_x/Bi₂O₃-BiVO₄The OCP of (1); FIG. 6(c) is BiV in 0.1M PBS (pH7.0) containing 500mM glucose under AM 1.5G illuminationO₄、Bi₂O₃-BiVO₄And NiFeO_x/Bi₂O₃-BiVO₄EIS curves at 0V (vs. ag/AgCl) bias. The inset shows its equivalent circuit model; FIG. 6(d) is a graph showing the concentration of 10mV s in 0.1M PBS (pH7.0) in the absence and presence of glucose^-1Recording the CV curve of GDH/1, 4-NQ/CNTs; FIG. 6(e) is the amperometric response of GDH/1,4-NQ/CNTs with continuous glucose addition in 0.1M PBS (pH7.0) at an applied bias of 0V (vs. Ag/AgCl) and FIG. 6(f) is the glucose calibration curve obtained in GDH/1, 4-NQ/CNTs; FIG. 6(g) is a graph showing that₂Saturation (dotted line) and O₂Saturated (solid line) 0.1M PBS (pH7.0) at 10mV s^-1LSV curves of BOD/CNT and BOD/PIX/CNT recorded at sweep rate and Tafel plot corresponding to FIG. 6 (h); FIG. 6(i) is a graph of 10mV s^-1BOD/PIX/CNTs recorded at sweep rate in O₂ORR polarization curves at different spin rates in saturated 0.1M PBS (pH7.0). The insert shows the corresponding K-L diagram

FIG. 7 shows the electrochemical performance of a photoanode, wherein FIG. 7(a) is 10mV s under AM 1.5G illumination in 0.1M PBS (pH7.0) containing 500mM glucose^-1Sweep speed record BiVO₄/FTO、 Bi₂O₃-BiVO₄FTO and NiFeO_x/Bi₂O₃-BiVO₄LSV curve for/FTO; FIG. 7(b) is a graph showing the concentration of 10mV s in the dark^-1Sweep speed record BiVO₄/FTO、Bi₂O₃-BiVO₄FTO and NiFeO_x/Bi₂O₃-BiVO₄LSV curve for/FTO.

FIG. 8 is NiFeO_x/Bi₂O₃-BiVO₄Electrochemical properties of the photoanode, wherein FIG. 8(a) is NiFeO under AM 1.5G illumination_x/Bi₂O₃-BiVO₄LSV profile of/FTO in 0.1mM PBS (pH 7.0); FIG. 8(b) is an amperometric response of M PBS (pH 7.0)/FTO in 0.1M PBS (pH7.0) in the absence and presence of glucose under an applied bias of 0V (vs. Ag/AgCl) under 1.5G illumination.

FIG. 9 is a MS curve of a photoanode prepared according to the present invention under dark conditions.

FIG. 10 is a representation of a photoanode prepared according to the present invention, wherein FIG. 10(a) is BiVO₄/FTO、 Bi₂O₃-BiVO₄FTO and NiFeO_x/Bi₂O₃-BiVO₄UV-visible diffuse absorption spectrum of/FTO photoanode, BiVO in FIG. 10(b)₄/FTO(I)、Bi₂O₃-BiVO₄FTO (II) and NiFeO_x/Bi₂O₃-BiVO₄Corresponding digital photographs of/FTO (III).

FIG. 11 is a graph showing the change in OCP of the GDH/1,4-NQ/CNTs bioanode after adding 100mM glucose to the buffer solution. The catalytic performance of the GDH/1,4-NQ/CNTs biological anode is optimized.

FIG. 12 is a graph of s at 10mV in 0.1M PBS (pH7.0) in the absence and presence of glucose^-1Recording CV curves for different amounts of 1,4-NQ GDH/1,4-NQ/CNT (FIGS. 12(a) - (e)), catalytic current density at 0V (vs. Ag/AgCl) as a function of 1,4-NQ dose (FIG. 12 (f)).

FIG. 13 is a CV curve of GDH/CNT recorded in 0.1M PBS (pH7.0) at a sweep rate of 10mV s-1 in the absence and presence of glucose.

FIG. 14 is the amperometric response (vs. Ag/AgCl) of GDH/1,4-NQ/CNTs at 0V bias with continuous addition of 5mM glucose, 0.2mM DA, 0.2mM AA, 0.2mM UA and 5mM glucose.

FIG. 15 is a graph showing that₂Saturation (dotted line) and O₂Saturated (solid line) in 0.1m PBS (pH7.0) at 10mV s^-1The sweep rates of BOD/CNTs and commercial Pt/C catalysts were recorded as LSV curves.

FIG. 16 is a graph of ORR performance of BOD-modified biocathodes, wherein FIG. 16(a) is static conditions, in the absence of glucose and in the presence of glucose, at N₂Saturation and O₂Saturated 0.1M PBS (pH7.0) at 10mV s^-1Recording the LSV curve of BOD/PIX/CNT; FIG. 16(b) is a graph of the concentration of glucose in the absence and presence of O under stirring conditions₂Saturated 0.1M PBS (pH7.0) at 10mV s^-1The sweep rate of (c) records the LSV curve of BOD/CNT.

FIG. 17 is a graph showing that₂Saturation and O₂Saturated 0.1M PBS (pH7.0) at 10mV s^-1The CV curve of PIX/CNTs was recorded.

FIG. 18 is the ORR performance of BOD/CNTs biocathodes in oxygen-saturated 0.1M PBS (pH7.0) at 10mV s^-1The ORR polarization curves of BOD/CNTs at different rotating speeds are recorded, and corresponding K-L curves are drawn.

FIG. 19 shows N under an applied bias of 0V (vs. Ag/AgCl)₂Saturation and O₂Ampere response of BOD/CNT and BOD/PIX/CNT in saturated 0.1M PBS (pH 7.0).

FIG. 20 is the ORR performance of BOD/CNTs and BOD/PIX/CNTs, wherein FIG. 20(a) is a RRDE voltammogram recording BOD/CNT and BOD/PIX/CNT in oxygen saturated 0.1M PBS (pH7.0) at 1600 rpm. Disk current (I)_d) (solid line) and annular Current (I)_r) (dotted line) is shown in the lower and upper half of the graph, respectively, at a scan rate of 10mV s^-1Ring potential 1.0V (vs. Ag/AgCl); FIG. 20(b) is a graph showing the determination of the peroxide (solid line) percentage and electron transfer number (n) (dashed line) of BOD/CNTs and BOD/PIX/CNTs at different potentials based on the corresponding RRDE data in FIG. 20 (a).

FIG. 21 is an EBFC and PEC performance wherein FIG. 21(a) is a schematic of an EBFC consisting of a GDH/1,4-NQ/CNTs bioanode and a BOD/PIX/BP biocathode, and the proposed working principle in the presence of glucose; FIG. 21(b) is a graph of s at 10mV in 0.1M PBS (pH7.0) in the absence (dashed line) and in the presence (solid line) of glucose^-1Recorded CV curves of GDH/1,4-NQ/CNT, and in N₂Saturation (dotted line) and O₂BOD/PIX/BP in 0.1M PBS (pH7.0) saturated (solid line); FIG. 21(c) is a graph of s at 1mV in oxygen-saturated 0.1M PBS (pH7.0) containing 100mM glucose^-1The sweep rate of (1) and the polarization and power output curves of the recorded EBFC, and continuous O₂Bubbling; FIG. 21(d) is a graph formed by NiFeO_x/Bi₂O₃-BiVO₄A PEC schematic diagram consisting of a photoanode and a BOD/PIX/BP biocathode, and a working principle in the presence of glucose; FIG. 21(e) S at 10mV in the presence of 500mM glucose under dark (dotted line) and irradiation (solid line) conditions^-1Scanning speed of (2) recording NiFeO_x/Bi₂O₃-BiVO₄LSV curve in 0.1M PBS (pH7.0), and in N₂Saturation (dotted line) and O₂BOD/PIX/BP curve in saturated (solid line) 0.1M PBS (pH 7.0); FIG. 21(f) continuous O in AM 1.5G illumination₂Under bubbling conditions, at 1mV s^-1In O containing 500mM glucose₂Polarization and power output curves of PECs recorded in saturated 0.1M PBS (pH 7.0).

Fig. 22 shows the BP and BOD/PIX/BP characterization, wherein fig. 22(a) -22 (c) are SEM images of BP, fig. 22(d) -22 (f) are SEM images of BOD/PIX/BP, and the arrow in fig. 22(f) points to BOD aggregates.

FIG. 23 shows GDH/1,4-NQ/CNTs bioanode, BOD/PIX/BP biocathode and assembled glucose/O₂OCP of biofuel cell.

FIG. 24 is NiFeO_x/Bi₂O₃-BiVO₄Tafel curves for photoanode and BOD/PIX/CNTs biocathode.

FIG. 25 shows NiFeOx/Bi₂O₃-BiVO₄Photoanode, BOD/PIX/BP biocathode and assembled glucose/O₂OCP of the photoelectrochemical cell.

FIG. 26 is an electrochemical performance of a constructed PEC without glucose, where FIG. 26(a) is the OCP of the cell under dark and irradiated conditions, and FIG. 26(b) is 1mV s in 0.1M PBS (pH7.0) saturated with oxygen, with AM 1.5G light, continuous oxygen sparging, and oxygen^-1The scan rate of (d) records the polarization and power output curves of the PEC.

FIG. 27 is an LSV curve of a PEC recorded under chopped AM 1.5G illumination in 0.1M PBS saturated with oxygen (pH7.0) at a sweep rate of 1mV s-1 in the absence of glucose.

FIG. 28 shows BPEC performance, where FIG. 28(a) is a graph formed by NiFeOx/Bi₂O₃-BiVO₄Schematic diagram of BPEC constructed by photoanode, GDH/1,4-NQ/CNTs biological anode and BOD/PIX/BP biological cathode, FIG. 28(b) is NiFeO_x/Bi₂O₃-BiVO₄And GDH/1,4-NQ/CNTs Mixed Anode in the Presence of 500mM glucose in the dark (dotted line) and irradiation (solid line) conditions at 10mV s^-1The LSV curve recorded in 0.1M PBS (pH7.0), andBOD/PIX/BP in N₂Saturation (dotted line) and O₂LSV curves recorded in 0.1M PBS (pH7.0) at saturation (solid line), FIG. 28(c) OCP in dark and irradiated conditions in the presence of 500mM glucose for mixed anodes, and FIG. 28(d) assembled BPEC in O in the presence of 500mM glucose in dark and irradiated conditions₂OCP in saturated 0.1M PBS (pH7.0), FIG. 28(e) as 1mV s^-1At a sweep rate of O containing 500mM glucose₂Saturated 0.1M PBS (pH7.0), O was continued₂Polarization curves under chopped AM 1.5G illumination of BPEC recorded under bubbling conditions, and fig. 28(f) is the corresponding power output curve.

FIG. 29 shows the construction of BPEC at 0.5V constant potential, O, in the presence of 500mM glucose₂Output power response curves for AM 1.5G illumination on-off cycles in saturated 0.1M PBS (pH 7.0).

FIG. 30 is NiFeO_x/Bi₂O₃-BiVO₄And (5) characterization before and after the photoanode i-t test. NiFeO_x/Bi₂O₃-BiVO₄SEM image of photo-anode before i-t test (FIG. 30(a)) and corresponding element mapping images of Bi (FIG. 30(b)), O (FIG. 30(c)) and V (FIG. 30(d)), NiFeOx/Bi₂O₃-BiVO₄SEM image after photo-anode i-t test (FIG. 30(e)) and corresponding element mapping images of Bi (FIG. 30(f)), O (FIG. 30(g)) and V (FIG. 30(h)), NiFeO_x/Bi₂O₃-BiVO₄EDS spectra before and after photoanode i-t test (FIG. 30(i) -FIG. 30(j)), NiFeO before and after i-t test_x/Bi₂O₃-BiVO₄Atomic percentages of Bi, V and O in the photoanode (fig. 30 (k)).

FIG. 31 is a BPEC system performance degradation mechanism study in which NiFeO_x/Bi₂O₃-BiVO₄The XPS spectra of X-ray diffraction (XRD) (FIG. 31(a)) Bi 4f (FIG. 31(b)) V2 p (FIG. 31(c)) Fe 2p (FIG. 31(d)) and Ni 2p (FIG. 31(e)) before and after 120 s ampere measurement were carried out, and ICP analysis of the electrolyte before and after 12000s ampere measurement was carried out in FIG. 31 (f).

FIG. 32 is a UV-vis absorption spectrum of an electrolyte.

FIG. 33 is a graph showing the current response of GDH/1,4-NQ/CNTs when 100mM glucose was added under a bias of O V (vs. Ag/AgCl) in 0.1M PBS (pH 7.0).

Detailed Description

The experimental procedures used in the following examples are all conventional procedures unless otherwise specified.

Sources of materials, reagents used in the following examples:

bismuth nitrate pentahydrate (Bi (NO)₃)₃·5H₂O, 99%), p-benzoquinone (99%), vanadium acetylacetonate (99%) and multi-walled carbon nanotubes (CNTs, 99.9%, external diameter 10-20nm) were purchased from shanghai alading biotechnology limited; FAD-dependent glucose dehydrogenase (GDH, 1170U mg)^-1From aspergillus) was purchased from Sekisui Diagnostics (UK) ltd.; BOD (40U mg)^-1From myxobacter verruciformis) was purchased from shanghai yuanye biotechnology limited; dimethyl sulfoxide, potassium iodide (KI, 99%), sodium hydroxide (NaOH, 97%), and nitric acid (HNO)₃65%, 1-methyl-2-pyrrolidone (NMP, 99.0%), ferrous sulfate heptahydrate (Fe (SO)₄)₂·7H₂O, 99.0%) and nickel sulfate hexahydrate (Ni (SO)₄)₂·6H₂O, 98.5%) was purchased from national drug chemicals, inc; buckypaper (BP) was purchased from north keisk corporation, 2D materials inc; protoporphyrin IX (PIX, 95%), lactic acid (80%), 1, 4-naphthoquinone (1,4-NQ, 97%), Nafion 117 solution (5% in a mixture of lower aliphatic alcohol and water), indium tin oxide doped with fluorine (FTO, 14. omega. cm)^-2) Conductive glass was purchased from Sigma Aldrich;

GDH solution (30mg mL) was prepared by dissolving the powder in 0.1M phosphate buffer solution (PBS, pH7.0)^-1) (ii) a BOD solution (10mg mL) was prepared by dissolving the powder in 0.1M PBS (pH7.0)^-1)。

All chemicals were analytical grade and were used as received without further purification.

Milli-Q ultrapure water (18.2 M.OMEGA.cm) was used throughout the preparation of the electrolyte solutions and all experiments were performed at room temperature.

Second, electrochemical and photoelectrochemical measurement methods in the following examples

To evaluate the performance of photoanode, bioanode and biocathode, electrochemical and photoelectrochemical measurements were performed using a typical three-electrode cell in which the photoanode, bioanode or biocathode was used as the working electrode, platinum foil (1 cm)²) As a counter electrode, Ag/AgCl (saturated KCl) was used as a reference electrode. 0.1M PBS (pH7.0) was used as electrolyte in the absence or presence of 500mM glucose. Cyclic Voltammetry (CV), LSV and chronoamperometric curves were recorded with CHI760E (shanghai chenhua instruments ltd). A Mott-Schottky (MS) curve was recorded in 0.1M PBS (pH7.0) containing 500mM glucose, at a potential window of-0.5 to 0V (vs. Ag/AgCl), at a medium frequency of 1000Hz and under 10mV dark conditions. The Oxygen Reduction Reaction (ORR) performance of the BOD-modified biocathode was further evaluated by using a rotating disk electrode and a rotating ring-disk electrode (RRDE-3A, ALS Co., Ltd., Japan).

To evaluate the performance of the photoanode, a 300W Xe lamp (PLS-SXE300D, beijing Perfectlight, china) with an AM 1.5G filter was used as the light source. Light intensity was calibrated to ca.100mW cm using a light radiometer (PL-MW 2000, Beijing Perfectlight, China)^-2. A shutter controller (PFS40A, beijing Perfectlight, china) was used to control the automatic shielding/unshielding of light in chopped illumination measurements. At a scan rate of 1.0mV s^-1Under the conditions of (1), the output power of the battery was evaluated from the OCP to the LSV of 0V.

Characterization of materials in the following examples

X-ray diffraction (XRD) data were collected using a smart lab (9) X-ray diffractometer (rija, japan) equipped with a Cu ka radiation source. Morphology and structure characterization was performed with a JSM-6701 field emission Scanning Electron Microscope (SEM) at 10kV acceleration voltage. Transmission Electron Microscopy (TEM) images were obtained using a JEL JEM-2100 microscope at 300 kV. Ultraviolet-visible absorption spectra (UV-vis) were obtained from UV-3600 (Shimadzu, Japan). X-ray photoelectron spectroscopy (XPS) was obtained using an AXISULTRA-DLD spectrometer (Quitous, Japan) equipped with an Al K.alpha.X-ray source. The electrolytes before and after the current measurement were analyzed by an inductively coupled plasma mass spectrometer (ICP-MS, ICAP RQ).

Example 1 NiFeOx/Bi₂O₃-BiVO₄Preparation of photo-anode

1、BiVO₄Preparation of photo-anode

By dissolving 30mM Bi (NO)₃)₃·5H₂O and 400mM KI were prepared in water (50 mL). By addition of HNO₃The pH was adjusted to 1.5. To the solution was slowly added 20mL of anhydrous ethanol containing 100mM of p-benzoquinone under stirring, and the mixture was stirred for 30min to obtain a plating solution. FTO is used as a working electrode, Ag/AgCl (saturated KCl) is used as a reference electrode, and Pt foil (1 cm)²) For the counter electrode, a typical three-electrode cell was used to electrodeposit the BiOI without agitation. A BiOI film was grown on the FTO using a continuous potential of-0.10V (vs. Ag/AgCl) for 400 s. The resulting BiOI/FTO was then rinsed with Milli-Q water and dried at room temperature. To convert a BiOI thin film into BiVO₄50 μ L cm containing 200mM vanadium acetylacetonate^-2And covering the dimethyl sulfoxide solution on the surface of the BiOI film. The electrode was then transferred to a muffle furnace in air at 450 ℃ for 2 hours (2 ℃ min)^-1). Naturally cooling to room temperature, immersing the electrode in 1M NaOH for 1h, and slightly stirring to remove BiVO₄Excess V present in the process₂O₅. Finally, the electrode was thoroughly rinsed with Milli-Q water and dried at room temperature to obtain BiVO₄And a photo-anode.

2、Bi₂O₃-BiVO₄Preparation of photo-anode

To prepare Bi₂O₃-BiVO₄The heterostructure is prepared by first calcining the electrodeposited BiOI/FTO in air at 500 ℃ for 2h (5 ℃ for min)^-1) Conversion of BiOI to Bi₂O₃And (3) a membrane. Subsequently, 50. mu.L cm containing 200mM vanadium acetylacetonate^-2Uniformly dripping the dimethyl sulfoxide solution in Bi₂O₃On a membrane, then continuously calcining at 450 ℃ for 2h (5 ℃ min) in air^-1). After natural cooling to room temperature, the electrode was immersed in 1M NaOH for 1h and gently stirred to remove Bi formed₂O₃-BiVO₄Excess of V present in₂O₅. Finally, the electrode was thoroughly rinsed with Milli-Q water and dried at room temperature to obtain Bi₂O₃-BiVO₄And a photo-anode.

3、NiFeOx/Bi₂O₃-BiVO₄Preparation of photo-anode

The NiFeO is prepared by a photoelectric deposition method under the irradiation of AM 1.5G by adopting a Linear Sweep Voltammetry (LSV)_xAn oxygen evolution promoter. Briefly, 20mg of Fe (SO)₄)₂·7H₂O and 2mg Ni (SO)₄)₂·6H₂O was dissolved in 200 mL of 0.5M borate buffer solution (pH 8.3). The resulting solution was purged with nitrogen for 30min before use. LSV testing was performed using a typical three-electrode cell with Bi₂O₃-BiVO₄FTO as working electrode, Ag/AgCl (saturated KCl) as reference electrode, Pt foil (1 cm)²) Is a counter electrode. In the potential range of-0.4V to 0.6V (vs. Ag/AgCl) at 10mV s under AM 1.5G illumination of the FTO back^-1Until the LSV curves overlap. The electrodes were rinsed thoroughly with Milli-Q water and dried at room temperature to obtain NiFeO_x/Bi₂O₃-BiVO₄And a photo-anode. The electrode area was controlled by applying a perforated opaque tape (diameter 6 mm).

BiOI/FTO (FIG. 1(a)) and Bi prepared in this example₂O₃XRD patterns of/FTO (FIG. 1(b)) As shown in FIG. 1, it can be seen from FIG. 1(a) that tetragonal phase BiOI was successfully grown on FTO glass, and from FIG. 1(b) that BiOI was converted to tetragonal Bi after calcination reaction at 500 ℃ for 2 hours in air₂O₃。

BiVO prepared in this example₄/FTO、Bi₂O₃-BiVO₄FTO and NiFeO_x/Bi₂O₃-BiVO₄The XRD pattern of/FTO is shown in FIG. 2, and it can be seen that BiVO is transformed after a series of heat treatments₄And Bi₂O₃-BiVO₄Heterojunctions were successfully synthesized.

BiOI/FTO (FIG. 3(a)) and BiVO prepared in this example₄FTO (FIG. 3(b)), Bi₂O₃-BiVO₄(FIG. 3(b)) and NiFeO_x/Bi₂O₃-BiVO₄FTO (FIG. 3: (d) SEM photograph of NiFeO) is shown in FIG. 3, and the inset shows NiFeO_x/Bi₂O₃-BiVO₄SEM photograph of/FTO cross section. As can be seen, the morphology of the BiOI film is composed of two-dimensional nanosheets with the thickness of 30-50 nm (figure 3(a)), and the gaps among the two-dimensional nanosheets can effectively inhibit BiVO₄The crystal growth in the calcining process forms nano-worm BiVO with the average grain diameter of about hundreds of nanometers₄(FIG. 3 (b)). Converted Bi₂O₃-BiVO₄Heterostructure (FIG. 3(c)) and NiFeO_x/Bi₂O₃-BiVO₄The inset of a thickness of about 1.75 μm ((FIG. 3(d)) shows a similar appearance to the original BiVO₄Similar morphology.

BiOI (FIG. 4(a)) and Bi prepared in this example₂O₃-BiVO₄(FIG. 4(b)) and NiFeO_x/Bi₂O₃-BiVO₄TEM image (FIG. 4(c)), BiOI (FIG. 4(d)), and Bi of the sample₂O₃-BiVO₄(FIG. 4(e)) and NiFeO_x/Bi₂O₃-BiVO₄HRTEM image of (FIG. 4(f)) (inset shows NiFeO_x/Bi₂O₃-BiVO₄FFT images in different regions), NiFeO_x/Bi₂O₃-BiVO₄The HADDF-STEM image of (B) and STEM-EDS element mapping images of the corresponding Bi, V, O, Ni and Fe ((FIG. 4(g)) are shown in FIG. 4. the 0.282nm and 0.301nm lattice fringes observed in FIG. 4(d) correspond to the (110) and (102) crystallographic planes of the tetragonal BiOI (JCPDS No. 10-0445). the 0.312nm and 0.319nm lattice fringes observed in FIG. 4(e) correspond to the monoclinic BiVO phase, respectively₄(JCPDS No.75-1866) and tetragonal phase Bi₂O₃(JCPDS No.78-1793) and (201) crystal planes, indicating the formation of a heterojunction. BiVO after photoelectric deposition₄An amorphous NiFeOx film about 5nm thick was attached to the surface (FIG. 4 (f)). NiFeO_x/Bi₂O₃-BiVO₄The HADDF-STEM diagram shows the uniform distribution of Ni, Fe, Bi, V and O elements, and proves that NiFeO_xNano-layer in nano-porous BiVO₄Successful deposition of the surface (fig. 4 (g)).

The results of elemental analysis of the electrode prepared in this example are as follows:

BiVO₄/FTO、Bi₂O₃-BiVO₄FTO and NiFeO_x/Bi₂O₃-BiVO₄The broad XPS spectra of/FTO, Bi 4f, V2 p and O1s XPS spectra are shown in FIGS. 5(a) -5 (d), respectively; NiFeO_x/Bi₂O₃-BiVO₄XPS spectra of Fe 2p and Ni 2p of/FTO are shown in FIGS. 5(e) to 5(f), respectively, and it can be seen that Ni and Fe are successfully deposited on Bi₂O₃-BiVO₄On the heterojunction.

Example 2 preparation of GDH functionalized bioanode

A glassy carbon electrode (GCE, diameter 3mm) was polished on a polishing cloth with 0.3 and 0.05 μm alumina slurries in sequence, sonicated continuously for 5min in Milli-Q water, acetone and Milli-Q water, and then N₂Dried under running water to form a mirror surface. The GDH functionalized bioanode is prepared by a simple drip method. Typically, 10. mu.L of carbon nanotube suspension (2.5mg mL)^-1A mixed solvent of isopropanol/water at a volume ratio of 1:3) was cast on the polished GCE surface and dried under infrared irradiation. mu.L of 1,4-NQ solution (100mM acetonitrile) was then cast onto the CNTs modified GCE. The electrode is dried under infrared light irradiation. Finally, 5. mu.L of LGDH solution was cast onto 1,4-NQ/CNTs modified GCE. The electrodes were stored in a refrigerator at 4 ℃ to evaporate the solvent. Finally, 2 μ L of the solution (1%) was cast as a binder onto GDH/1,4-NQ/CNTs modified GCE surface and stored in a refrigerator at 4 ℃ with evaporation of the solvent.

Example 3 preparation of BOD modified biocathodes

The preparation method of the BOD modified biological cathode is similar to that of the GDH biological anode. Namely, 10. mu.L of carbon nanotube suspension (2.5mg mL)^-1Isopropanol/water mixed solvent, volume ratio 1:3) is cast on the surface of the polished GCE and dried under infrared irradiation. And soaking the carbon nano tube modified electrode in a PIX solution (0.5mM, NMP) for 1h to adsorb PIX molecules onto the carbon nano tube. After the adsorption process was complete, the electrode was rinsed with Milli-Q water to remove loosely adsorbed PIX molecules and dried under infrared light. mu.L of BOD solution containing 0.5% Nafion was cast onAnd (3) modifying the electrode by PIX/CNTs. The electrodes were stored in a refrigerator at 4 ℃ and the solvent was evaporated before use.

EBFCs, PECs and BPEC were prepared with BOD modified BP instead of GCE. Briefly, BP (1X 1cm) was immersed for 1h in NMP solution containing 0.5mM PIX to absorb PIX molecules, then rinsed with Milli-Q water and dried under infrared irradiation. 50 μ L of BOD solution containing 0.5% Nafion was cast onto PIX/BP. The resulting BOD/PIX/BP was then stored in a refrigerator at 4 ℃ to evaporate the solvent. And finally, pasting BOD/PIX/BP on the copper conductive tape to obtain the biological cathode.

Example 4 electrochemical Performance of the electrode

1. Photoelectrocatalysis performance of photoanode

For BiVO₄、Bi₂O₃-BiVO₄And NiFeO_x/Bi₂O₃-BiVO₄LSV experiment is carried out on the photoanode, and the photoelectrocatalysis performance of the photoanode on glucose oxidation is evaluated.

As shown in FIG. 6(a), the chopped photocurrent-potential curve clearly shows that NiFeOx/Bi₂O₃-BiVO₄Photo-anode (0.6V,1.7mA cm)^-2vs. Ag/AgCl) showed significantly higher levels than Bi under AM 1.5G illumination₂O₃-BiVO₄ (0.6V,1.0mA cm^-2ag/AgCl) and BiVO₄(0.6V,0.6mA cm^-2ag/AgCl) photocurrent density. All photoanodes have a fast photo-response under chopped illumination, and the current approaches zero under dark conditions, indicating that the oxidation of glucose is driven by photo-generated carriers. Further, NiFeO_x/Bi₂O₃-BiVO₄The anodic catalysis of the photoanode starts at-0.35V (vs. Ag/AgCl), which is the ratio of Bi₂O₃-BiVO₄And BiVO₄The anode catalyst (2) is slightly negative (fig. 7 (a)). In addition, with BiVO₄And Bi₂O₃-BiVO₄In contrast, NiFeO_x/Bi₂O₃-BiVO₄The photoanode observed a more negative electrocatalytic onset potential shift of about 100mV and a steeper glucose oxidation current under dark conditions (fig. 7 (b)). These results show that Bi₂O₃-BiVO₄Of a heterojunctionConstruction and NiFeO_xThe pairing of the promoters can realize effective interface charge transfer and inhibit photogenerated electron-hole recombination.

Importantly, the NiFeO provided by the invention_x/Bi₂O₃-BiVO₄The photoanode also exhibited the desired water oxidation capacity in the absence of glucose (fig. 8). The addition of 500mM glucose in the buffer solution resulted in a strong increase in the anodic current, indicating that oxidation of glucose significantly promoted the anodic current. Measurement of BiVO under light and dark conditions₄、Bi₂O₃-BiVO₄And NiFeO_x/Bi₂O₃-BiVO₄Open circuit voltage (OCP) of the photo-anode. Under light and dark conditions, the change in OCP is caused by quasi-fermi level splitting of the photo-generated electrons and holes under light, and an increase in OCP indicates a high surface hole concentration. As shown in FIG. 6(b), Bi₂O₃-BiVO₄After the heterojunction is constructed, the OCP is increased; bi₂O₃-BiVO₄Heterojunction and NiFeO_xAfter co-catalyst pairing, the OCP was further enhanced, indicating a high surface hole concentration. Notably, no catalytic current passes under open circuit conditions, and therefore, Bi₂O₃-BiVO₄And NiFeO_x/Bi₂O₃-BiVO₄The open circuit photovoltage enhancement indicates that the heterojunction and the NiFeOx induced oxygen defects only promote the surface reaction.

To understand the kinetics of interfacial charge transfer during glucose oxidation, BiVO was measured under AM 1.5G illumination at an applied voltage of 0V (vs. Ag/AgCl)₄、Bi₂O₃-BiVO₄And NiFeO_x/Bi₂O₃-BiVO₄Electrochemical Impedance Spectroscopy (EIS) of the photoanode. As shown in fig. 6(c), the three EIS curves consist of only one half circle, indicating that there is only one time constant in the curve. Using a series resistor (R)_s) Charge transfer resistance (R)_ct) And constant phase angle element (CPE) (inset in fig. 6 (c)) fit the curve very well. Of particular note is R_ctRepresenting the charge at the electrode/electrolyte interfaceTransfer resistance, greater R_ctThe values reflect slow interfacial charge transfer. BiVO as shown in Table 1₄And Bi₂O₃-BiVO₄R of (A) to (B)_ctThe values were 6484 and 4908. omega. respectively, indicating Bi₂O₃-BiVO₄ET at the interface with electrolyte is faster than BiVO₄Interface with the electrolyte. Bi₂O₃-BiVO₄With NiFeO_xAfter layer pairing, R_ctThe value was further reduced to 1684 Ω. Thus, NiFeO was used_x/Bi₂O₃-BiVO₄The photoanode can achieve higher PEC performance. Furthermore, BiVO₄、Bi₂O₃-BiVO₄And NiFeO_x/Bi₂O₃-BiVO₄The MS curve of the photoanode is positively sloped (fig. 9), indicating its n-type character. In addition, Bi₂O₃-BiVO₄And NiFeO_x/Bi₂O₃-BiVO₄Slope ratio BiVO of photo-anode₄Small, indicating the construction of the heterojunction and the formation of NiFeO_xThe pairing of the promoters allows for higher carrier densities. Note that the intercepts on the x-axis of the three photoanodes are similar, indicating that they have similar charged potentials, consistent with similar initial potentials for glucose oxidation (fig. 7 (a)). In addition to the fast charge transfer kinetics at the electrode/electrolyte interface, NiFeO_x/Bi₂O₃-BiVO₄The excellent glucose oxidation performance of the photoanode was also attributed to the enhanced light absorption capacity as shown by the UV-vis diffuse absorption spectrum (fig. 10 (a)). This is in conjunction with BiVO₄From bright yellow to Bi₂O₃-BiVO₄And NiFeO_x/Bi₂O₃-BiVO₄The color change of the dark yellow color (fig. 10(b)) was very uniform. The color change is likely due to the heterojunction and the deposited promoter layer in the nanoporous BiVO₄Significant disorder effects are created in the atomic arrangement of the surface (e.g., oxygen defects).

TABLE 1 fitting results of EIS curves in FIG. 6(c)

2. Bioelectrocatalytic oxidation performance of GDH/1,4-NQ/CNTs bioanode

The bioelectrocatalytic oxidation of GDH/1,4-NQ/CNTs bioanode to glucose was investigated by CV method. FIG. 6(d) shows CV curves for GDH/1,4-NQ/CNTs bioanode in the presence and absence of 100mM glucose in 0.1M PBS (pH 7.0). In the absence of glucose, a pair of redox peaks at an apparent potential of-0.145V (vs. Ag/AgCl) was detected, corresponding to the redox reaction of the mediator 1, 4-NQ. Addition of 100mM glucose to the buffer solution resulted in a decrease of OCP from-0.08V to-0.21V (vs. Ag/AgCl) (FIG. 11). In addition, 1,4-NQ mediated biocatalytic glucose oxidation started at a low initial potential of-0.2V (vs. Ag/AgCl) while achieving 1.63mA cm at 0.01V (vs. Ag/AgCl)^-2High catalytic current density. The ability of the GDH/1,4-NQ/CNTs bioanode to produce more negative OCP and high current density at low potentials is desirable because it can increase the OCP of EBFCs and help increase power density. The concentration of 1,4-NQ in the GDH/1,4-NQ/CNTs bioanode was optimized, as shown in FIG. 12, increasing the 1,4-NQ loading resulted in an increase in the catalytic current density for glucose oxidation, and the response current reached a maximum at a 1,4-NQ dose of 3. mu.L. When the 1,4-NQ dose is higher, the response current of the bioanode is significantly reduced, which may be due to blockage caused by overloading of the 1,4-NQ in the carbon nanotube network channels, resulting in ineffective electron transfer capability of the mediator 1, 4-NQ. Therefore, the preparation process of 1,4-NQ is optimized by the dosage of 3 mu L. It is worth noting that GDH/CNTs bioanode prepared in the absence of 1,4-NQ did not exhibit catalytic properties for its substrate glucose (fig. 13), indicating that there was no direct bioelectrocatalysis between the active site of GDH and the electrode surface, further emphasizing the role of 1,4-NQ in mediating charge transfer during GDH catalyzed glucose oxidation.

FIG. 6(e) shows the Ampere response of the GDH/1,4-NQ/CNTs bioanode to the continuous addition of glucose in buffer solution. After addition of glucose, the response current increased and reached a steady state of 6s within 30 minutes, indicating that the prepared bioanode reacted rapidly to changes in substrate concentration. The concentration of the biological anode is 0-8 mMThe glucose sensor has linear response to glucose within the range, the correlation coefficient is 0.998, and the slope is 0.05mA cm^-1mM^-1(FIG. 6 (f)). Considering that the apparent area of the bioanode is 0.07cm²Therefore, the sensitivity was estimated to be 7.14mA mM^-1cm^-2. The sensitivity is much higher than that of glucose oxidase (GOx)/carbon quantum dot-gold nanoparticle nano hybrid (626.06 mu A mM)^-1cm^-2) And GOx/poly (3, 4-ethylenedioxythiophene) modified carbon fiber (8.5. mu.A mM)^-1cm^-2). In addition, the constructed bioanode showed high selectivity for glucose and anti-interference properties (fig. 14), indicating that the constructed bioanode is suitable for application in a glucose biosensor.

3. BOD/PIX/CNTs biological cathode performance

At biocathodes, BOD was used as a reductase for electrocatalytic ORR because it has a higher initial catalytic potential and larger ORR current than commercial Pt/C catalysts (fig. 15). Most importantly, the specific catalytic capacity for ORR is hardly affected in the presence of glucose (figure 16), which makes BOD available for the manufacture of membrane-free BFCs. In order to further improve ORR performance, PIX is used as a direct electron transfer promoter to modify the carbon nano tube, so that the directional immobilization of BOD is realized. Notably, PIX itself does not catalyze ORR (fig. 17), which can act as a bridge to lower the overpotential of ORR and accelerate the electron transfer between BOD active sites and the electrode surface. As shown in FIG. 6(g), the cathode catalysis of BOD/PIX/CNTs biocathodes starts from 0.58V (vs. Ag/AgCl), and the catalytic current density rapidly reaches 553. mu.A cm under the conditions of oxygen saturation and 0.5V (vs. Ag/AgCl)^-2Higher than BOD/CNTs biological cathode (initial potential of 0.54V, 353 mu A cm)^-20.39V). The results show that the presence of PIX reduces the overpotential of ORR, increasing the catalytic kinetics of ORR. BOD/PIX/CNTs biological cathode (154mV dec)^-1) The excellent ORR activity can be obtained by the specific BOD/CNTs biocathode (54.7mV dec)^-1) The smaller slope of the Tafel curve is further determined (fig. 6 (h)). Notably, the catalytic wave in the LSV curve (fig. 6(g)) exhibited a peak shape, indicating the occurrence of a hindered ORR process, which is primarily due to O under static conditions₂Because of dissolved O in solution at room temperature₂The concentration is less than 1 mM.

Further evaluation of BOD/PIX/CNTs and BOD/CNTs biocathodes at O₂ORR performance in saturated 0.1M PBS (pH 7.0). A rotating disk electrode with fixed BOD/PIX/CNTs or BOD/CNTs is used as a working electrode. FIG. 6(i) shows ORR polarization curves of BOD/PIX/CNTs biocathodes in 0.1M PBS (pH7.0) saturated with oxygen at different rotational speeds and the corresponding Koutech-Levich (K-L) plot in the inset. At a rotational speed of 2025rpm, an ORR limiting current density of 2.78 mA cm was observed for the BOD/PIX/CNTs biocathodes^-2Greater than the limiting current density (1.86mA cm) of the BOD/CNTs biological cathode^-2) (FIG. 18), reflecting the superior mass transfer performance and enhanced ORR activity of BOD/PIX/CNTs biocathodes. Impressively, BOD/PIX/CNTs biocathodes exhibited good operating stability, with the ORR current remaining 96.5% of its stable ORR current after 4 hours of operation (fig. 19), higher than the BOD/CNTs biocathodes without PIX (88.4%), suggesting that the introduction of PIX in the preparation of BOD biocathodes can significantly improve the ORR activity and stability of the biocathodes. Rotating ring-disk electrode measurements revealed that the peroxide species formation of BOD/PIX/CNT was less than BOD/CNT and that both biocathodes could be at 4e^-Reduction of O in the pathway₂(FIG. 20), further highlighting the advantage of BOD in catalyzing ORR.

The current of 30min was chosen to define a stable ORR current. Therefore, the ORR current holding ratio was calculated by dividing the current value at 4h by the current value at 30 min.

EXAMPLE 5 electrochemical Performance of assembled batteries

The membrane-free EBFC was assembled by coupling GDH/1,4-NQ/CNTs bioanode and BOD/PIX/BP biocathode (fig. 21 (a)). On the GDH/1,4-NQ/CNTs bioanode, GDH catalyzes the oxidation of glucose to produce glucose lactone and proton, while the active site of GDH (FAD) is reduced to FADH 2. The 1,4-NQ molecule acts as an exogenous electron shuttle mediating electron transfer between GDH (FADH2) and the electrode surface. Notably, mediated electron transfer is critical to achieving electronic communication between GDH and the electrode, since there is no electron transfer betweenDirect bioelectrocatalysis does not occur in the case of 1,4-NQ (FIG. 13). For BOD/PIX/BP biocathodes, comparing SEM images of BP and BOD/PIX/BP, it was found that BOD aggregates were successfully immobilized on the PIX/BP surface (fig. 22). These targeted BOD biomolecules pick up electrons from the bioanode through an external circuit. Specifically, one mononuclear type 1 (T1) Cu site accepts electrons. The electrons shuttle from the T1-Cu position to the trinuclear type 2 (T2)/type 3 (T3) Cu position through internal electron transfer to realize 4e of oxygen^-Reducing the reaction product into water. The advantage of this direct bioelectrocatalysis is that it does not require the use of exogenous redox mediators, thus avoiding potential loss due to the potential difference between the active site of the enzyme and the mediator, and simplifying the electrode preparation process.

FIG. 21(b) shows CV curves for GDH/1,4-NQ/CNTs bioanode and BOD/PIX/BP biocathode, where mediated enzymatic glucose oxidation and direct bioelectrocatalytic ORR process can be observed, respectively. The OCP of the GDH/1,4-NQ/CNTs bioanode reached-0.22V (vs. Ag/AgCl) in the presence of 500mM glucose, which enabled the extraction of electrons from the biocatalytic oxidation of glucose at a fairly negative potential (FIG. 23). For BOD/PIX/BP biocathodes, in O₂The saturation condition produces 0.57V (vs. Ag/AgCl) of OCP, which allows the ORR to be at a fairly positive bias. Thus, glucose/O of the Assembly₂The OCP of EBFC can reach about 0.8V. Fig. 21(c) shows cell voltage and power density as a function of current density. Notably, there is a lack of kinetic loss in the polarization curve, indicating rapid charge transfer kinetics in the electrode reaction. Assembled glucose/O under oxygen saturation conditions₂Maximum Power Density of 1.17mW cm for EBFC at 0.51V^-2. When the potential of the battery is reduced to zero, the maximum current density reaches 2.61mA cm^-2. The large noise observed in the low potential range of the battery in the polarization and power output curves indicates that the battery performance is mainly limited by the biocathodes, which is consistent with the bioelectrocatalytic behavior of the biocathodes (fig. 21 (b)).

To evaluate the NiFeO thus prepared_x/Bi₂O₃-BiVO₄Feasibility of the photoanode in obtaining electric energy by using BOD/PIX/BP biocathode and NiFeOx/Biglucose/O was constructed by 2O3-BiVO4 photoanode₂PEC (fig. 21 (d)). In principle, NiFeO_x/Bi₂O₃-BiVO₄The photoanode generates electrons and holes under AM 1.5G illumination. Photo-generated electrons are separated and then transferred to a biological cathode for ORR, while holes are substituted by glucose/H₂And (4) consuming the O. glucose/H₂The photoelectrocatalytic oxidation and direct bioelectrocatalytic ORR process of O is shown in fig. 21 (e). Notably, glucose/H₂The photoelectrocatalytic oxidation of O starts at-0.35V (vs. Ag/AgCl), which is more negative than the 1, 4-NQ-mediated glucose oxidation (-0.20V vs. Ag/AgCl, FIG. 1(b)), indicating glucose/H₂The photoelectrocatalytic oxidation of O is thermodynamically more favorable than the 1, 4-NQ-mediated biocatalytic oxidation of glucose. The main reason for this is that 1,4-NQ has a high redox potential. Therefore, the development of a novel mediator which can shuttle electrons and has low oxidation-reduction potential is of great significance for realizing a high-performance GDH-based bioanode. Although glucose/H₂The initial potential for O-oxidation was low, but the photoelectrocatalytic current density reached 0.57mA cm only at 0V (vs. Ag/AgCl) bias^-2This is much lower than GDH/1,4-NQ/CNTs bioanode (1.67mA cm)^-2FIG. 1(b)), demonstrating glucose/H₂Kinetic unfavorable properties of the photoelectrocatalytic oxidation. Further, NiFeO_x/Bi₂O₃-BiVO₄The relatively slow oxidative activity of the photoanode can be measured by its higher Tafel curve slope (490mV dec)^-1) To determine that it is higher than ORR activity of biological cathode of BOD/PIX/CNTs (54.7mV dec)^-1) (FIG. 24). The results show that in NiFeO_x/Bi₂O₃-BiVO₄On photoanodes, PEC systems are limited by relatively slow kinetics of the oxidation reaction.

Photoanode, biocathode and constructed glucose/O₂The OCP of the PEC is shown in FIG. 25. NiFeO in oxygen-saturated buffer solution under the irradiation of AM 1.5G and 500mM glucose_x/Bi₂O₃-BiVO₄The anode OCP of the photoanode is-0.36V (vs. Ag/AgCl), the cathode OCP of the BOD/PIX/BP biological cathode is 0.57V (vs. Ag/AgCl), and glucose/O (glucose/oxygen) formed by the anode OCP and the cathode OCP is₂-the OCP of the PEC is about 0.83V,lower than the OCP (0.93V) of the photoanode and the biocathode. The reduction in voltage is primarily due to the ohmic internal resistance of the battery. Under AM 1.5G illumination, the maximum power density of the constructed PEC at 0.42V is 0.29mW cm^-2Short-circuit current density of 1.3mA cm^-2(FIG. 21 (f)). Notably, in the absence of glucose, at O₂The PEC constructed in the saturated buffer can still provide 0.66V OCP and generate 0.087mW cm at 0.3V^-2Maximum power density (fig. 26), indicating that the PEC system is capable of water/oxygen cycling. LSV measurements of the PEC under chopped illumination showed that the system was unable to generate electricity under dark conditions (fig. 27) and was therefore intermittently limited by sunlight.

In view of the excellent performance of EBFC under dark and PECs illumination, GDH/1,4-NQ/CNTs bioanode, NiFeO_x/Bi₂O₃-BiVO₄Integration of photoanode and BOD/PIX/BP biocathode into single-compartment cells constructed novel BPECs (fig. 28 (a)). There are two electron transfer paths in a BPEC system based on different energy conversion processes. One is the bioelectrocatalytic oxidation of glucose. Generally, GDH/1,4-NQ/CNTs bioanode catalyzes the oxidation of glucose to produce glucolactone and proton, the produced electron is transferred to BOD/PIX/BP biocathode, and the dissolved O₂Is reduced to H₂And O, realizing the conversion from chemical energy to electric energy. Notably, this process can be done in the dark, as well as under irradiation, thereby addressing the problem of PEC systems not being able to generate electricity under dark conditions. Secondly, the photoelectrocatalysis oxidation of glucose. NiFeO_x/Bi₂O₃-BiVO₄The photoanode generates electrons and holes under AM 1.5G illumination. These cavities are filled with glucose/H₂Consumption of O to produce gluconic acid and O₂And protons, the photo-generated electrons are transferred to the BOD/PIX/BP biocathode, O is₂Reduction to H₂And O, realizing conversion from optical energy/chemical energy to electric energy. The mixed anode can generate 3.2mA cm in dark^-2The oxidation current density of (2) can be considerably large, 6.0mA cm under AM 1.5G illumination^-2Oxidation current density of (b) in fig. 28. OCP of the hybrid anode from-0.22V in the dark(vs. Ag/AgCl) to-0.33V (vs. Ag/AgCl) under light (FIG. 28 (c)).

The invention also characterizes the electrochemical performance of the all-weather power generation conceptual model. As shown in fig. 28(d), the OCP of the battery was photosensitive and changed from 0.78V in the dark to 0.83V in the illumination. Then in O containing 500mM glucose₂LSV was performed in saturated buffer to evaluate the performance of constructed BPEC. Fig. 28(e) shows the chopped light voltammetry performance of the cell. The short-circuit current density under dark and irradiation conditions reaches 2.51 and 4.84mA cm respectively^-2. Impressively, the cell can output a maximum power density of 1.33mW cm from darkness^-2Changing to 1.76mW cm under light^-2(FIG. 28(f)), showing the most advanced performance in the literature reported so far (Table 2). The above results represent an example of an integrated BPEC in which both current density and power output are increased by an order of magnitude under dark or light conditions by a bio-photoelectrode combination.

TABLE 2 BPEC Performance comparison^a

^aGOx ═ glucose oxidase, P_OsFAD-GDH ═ flavin adenine dinucleotide-dependent glucose dehydrogenase, PSII ═ photosystem II, IO-ATO ═ inverse opal antimony tin oxide, PC ═ pyrenecarboxylic acid, BOD ═ bilirubin oxidase, FTO ═ fluorine-doped tin oxide, ITO ═ indium tin oxide, TCPP ═ meso-tetrakis (4-carboxyphenyl) -porphine, BP ═ buckypaper, 1-PA ═ 1-pyrenebutyric acid, MDB ═ meldola blue, MWNTs ═ multiwalled carbon nanotubes, PB/PW prussian blue/prussian white, GOD ═ glucose oxidase, TTF-OMC ═ tetrathiafulvalene ordered mesoporous carbon, pMBQ ═ poly (mercapto-p-benzoquinone), pTTh ═ ethanol dehydrogenase, adhth ═ polythiophene, 1,4-NQ ═ 1, 4-naphthoquinone, PIX ═ 1, and proto.

^bThe battery structure shown in fig. 21 (d). Cell performance in oxygen saturated 0.1M PBS: (pH7.0), containing 500mM glucose, AM 1.5G light, under continuous oxygen bubbling conditions.

^cThe battery structure shown in fig. 28 (a). Cell performance was measured under oxygen-saturated 0.1M PBS (pH7.0), containing 500mM glucose, AM 1.5G light, with continuous oxygen sparging.

^dThe battery structure shown in fig. 21 (d). Cell performance was measured under oxygen-saturated 0.1M PBS (pH7.0), containing 500mM glucose, in the dark, with continuous oxygen sparging.

The long-term operating stability of the BPECs was evaluated by current measurements under intermittent illumination. After 12000s, the cell was kept at 0.052mW cm under dark conditions^-2The power density of (1) is kept at 0.16mW cm under the illumination condition^-2Power density of (1) (fig. 29). In addition, there is a tendency for the power output to gradually decrease throughout operation. The performance degradation mechanism of the BPEC was investigated. By the reaction on NiFeO_x/Bi₂O₃-BiVO₄SEM comparison research before and after 12000s current measurement of the photoanode shows that BiVO₄The gaps between the nanoparticles are large, while NiFeO_x/Bi₂O₃-BiVO₄Is significantly reduced after current measurement (fig. 30). For NiFeO_x/Bi₂O₃-BiVO₄Also shows a decrease in diffraction peak intensity after amperometric measurement (fig. 31(a)), indicating BiVO₄Slightly dissolved. NiFeO_x/Bi₂O₃-BiVO₄The XPS spectra of (A) further showed that the intensity of Bi 4f, V2 p, Fe 2p peaks was significantly reduced and the Ni 2p peak disappeared after 12000s of amperometric measurement (FIG. 31(b) -FIG. 31 (e)). Further, the ICP-MS results of the electrolytic solutions before and after the 12000s current measurement did show that the concentrations of Ni, Fe, Bi, and V elements were increased after the current measurement (fig. 31 (f)). The results show that NiFeO_x/Bi₂O₃-BiVO₄The leaching of medium Ni, Fe, Bi and V is the major component change during long-term operation. In addition, the uv-vis absorption spectrum of the electrolyte showed that the enzyme and mediator 1,4-NQ were eluted into the electrolyte after 12000s of ampere operation (fig. 32). In addition to this, the present invention is,enzyme inactivation during operation was also observed in the gradual decrease of the catalytic current at the GDH/1,4-NQ/CNTs bioanode (fig. 33) and at the BOD/PIX/CNTs biocathode (fig. 19).

The above illustrates a concept-verified design of a BPEC system for all-weather power generation by light and biofuel conversion. The maximum power output density of the conceptual model is 1.76mW cm^-2OCP was 0.83V under AM 1.5G illumination, 0.78V under dark condition, and maximum output power density was 1.3mW cm^-2. The excellent performance of BPEC can be attributed to the following reasons. First, passing Bi₂O₃-BiVO₄Construction of heterojunction and pairing with NiFeOx cocatalyst, BiVO₄Base photo anode pair glucose/H₂The photoelectrocatalysis performance of O is obviously improved. Second, well-designed bioelectrode structures allow for fast electrode kinetics for 1, 4-NQ-mediated glucose oxidation and BOD-catalyzed ORR. Finally, the spatially separated arrangement of biological components and non-biological entities enhances the compatibility between PECs and EBFCs, enabling the system to work independently or in concert.