阅读说明：本技术 一种自支撑电极基底材料及基于其的双室酶生物燃料电池 (Self-supporting electrode substrate material and double-chamber enzyme biofuel cell based on same ) 是由 吴抒遥 姜美娇 赵楠 隋成荃 陈奇男 马多 宋溪明 于 2021-08-24 设计创作，主要内容包括：本发明涉及一种自支撑电极基底材料及基于其的双室酶生物燃料电池。采用的技术方案是：将强酸处理后的碳纸分别在碳酸钾溶液、硝酸钾的磷酸盐缓冲溶液中进行两步电化学剥离。然后将所得材料进行电化学沉积金纳米粒子,将其作为集流体固载酶,制备了基于碳纸为载体的葡萄糖氧化酶修饰电极。以HEG/Au-GOx电极为生物阳极,HEG/Au-Lac电极为生物阴极,葡萄糖作为生物燃料,制备双室酶生物燃料电池。本发明的双室酶生物燃料电池成本低,制备简单,且可以达到较大的功率密度。(The invention relates to a self-supporting electrode substrate material and a dual-chamber enzyme biofuel cell based on the same. The technical scheme is as follows: and (3) respectively carrying out two-step electrochemical stripping on the carbon paper treated by strong acid in a potassium carbonate solution and a phosphate buffer solution of potassium nitrate. And then carrying out electrochemical deposition on the obtained material to obtain gold nanoparticles, and taking the gold nanoparticles as a current collector to immobilize enzyme to prepare the glucose oxidase modified electrode based on carbon paper as a carrier. Preparing a double-chamber enzyme biofuel cell by taking an HEG/Au-GOx electrode as a biological anode, an HEG/Au-Lac electrode as a biological cathode and glucose as a biofuel. The double-chamber enzyme biofuel cell has low cost and simple preparation, and can reach higher power density.)

1. A self-supporting electrode substrate material is characterized in that the preparation method comprises the following steps:

1) treating the pretreated carbon paper with strong acid;

2) taking carbon paper treated by strong acid as a working electrode, an Ag/AgCl electrode as a reference electrode and a platinum wire as a counter electrode, placing the three-electrode system in a potassium carbonate aqueous solution, and carrying out first-step electrochemical stripping;

3) taking the carbon paper electrochemically stripped in the first step as a working electrode, an Ag/AgCl electrode as a reference electrode and a platinum wire as a counter electrode, placing the three-electrode system in a phosphate buffer solution of potassium nitrate, and carrying out electrochemical stripping in the second step;

4) and (3) taking the carbon paper electrochemically stripped in the second step as a working electrode, an Ag/AgCl electrode as a reference electrode and a platinum wire as a counter electrode, placing the three-electrode system in a gold-containing solution, carrying out electrodeposition, depositing a layer of gold nanoparticles on the surface of the carbon paper, washing the obtained material with deionized water, and drying to obtain the self-supporting electrode substrate material with the three-dimensional structure.

2. The self-supporting electrode substrate material as claimed in claim 1, wherein in step 1), the carbon paper is hydrophilic carbon paper.

3. The self-supporting electrode substrate material as claimed in claim 1, wherein the step 1) is specifically: uniformly mixing concentrated nitric acid and concentrated sulfuric acid according to the volume ratio of 3:1 to obtain a strong acid mixed solution, dropwise coating the strong acid mixed solution on the pretreated carbon paper, standing at room temperature for 5 minutes, and washing with deionized water to be neutral.

4. The self-supporting electrode base material as claimed in claim 1, wherein in the step 2), the concentration of the potassium carbonate aqueous solution is 0.5 mol/L; in the first step of electrochemical stripping process, the scanning potential is 0.5-1.8V, the number of scanning cycles is 6, and the scanning rate is 20mV s^-1。

5. The method of claim 1The self-supporting electrode substrate material is characterized in that in the step 3), the pH value of the phosphate buffer solution of potassium nitrate is 7, and the concentration of potassium nitrate is 1 mol/L; in the second step of electrochemical stripping process, the scanning potential is-0.9-1.9V, the number of scanning cycles is 6, and the scanning rate is 20mV s^-1。

6. The self-supporting electrode substrate material as claimed in claim 1, wherein in step 4), the gold-containing solution is a mixed solution of chloroauric acid and sulfuric acid, the electrodeposition voltage is-4V, and the electrodeposition time is 300 s.

7. A double-chamber enzyme biofuel cell based on self-supporting electrode substrate material is characterized in that the preparation method comprises the following steps:

1) preparation of the biological anode: soaking the self-supporting electrode substrate material of any one of claims 1 to 6 in a glucose oxidase solution at 4 ℃ overnight to obtain a bioanode;

2) preparing a biological cathode: dripping the enzyme dispersion liquid on the surface of the self-supporting electrode substrate material of any one of claims 1 to 6, and drying at room temperature to obtain a biocathode;

3) preparing a double-chamber enzyme biofuel cell: the biological anode is used as an anode, the biological cathode is used as a cathode, two polar chambers are separated by a Nafion 211 membrane, PBS buffer solution with the pH value of 5 of glucose is filled in the anode chamber, HAc-NaAc buffer solution with the pH value of 5 saturated by oxygen is filled in the cathode chamber, and the double-chamber enzyme biofuel cell is formed.

8. The self-supporting electrode substrate material based dual-chamber enzyme biofuel cell of claim 7, characterized in that in step 1), the concentration of the glucose oxidase solution is 5 mg/mL.

9. The self-supporting electrode substrate material-based dual-compartment enzyme biofuel cell of claim 7, characterized in that in step 2) the concentration of the laccase dispersion is 5 mg/mL.

10. The self-supporting electrode substrate material-based dual-chamber enzyme biofuel cell of claim 7, wherein in step 3), the concentration of glucose in PBS buffer solution with pH 5 is 60-100 mM.

Technical Field

The invention belongs to the field of electrode materials of biofuel cells, and particularly relates to a self-supporting electrode substrate material and a double-chamber enzyme biofuel cell based on the same.

Background

The biological fuel cell is a clean and high-efficiency green energy which is widely concerned. Enzyme biofuel cells (EBFCs), a subclass of biofuel cells, generate electricity from renewable fuels such as carbohydrates, urea, and organic acids by electrochemical oxidation occurring at the anode using enzymes. They are lower in cost, generate electricity from renewable energy under mild conditions, and are selective to fuels compared to other conventional energy systems. These advantages make them suitable candidates for implantable medical devices, such as pacemakers and mini-drug pumps, and even for devices such as wastewater treatment, drug delivery, biosensors, and the like.

Glucose oxidase (GOx) is the most favored enzyme in enzyme biofuel cells due to its availability and high selectivity for glucose. The most challenging part of the current production of high performance enzymatic biofuel cells is the efficient immobilization of enzymes on the electrode surface. The limitations of GOx immobilization on the electrode surface are mainly the problems of leaching of enzyme, short enzyme life, poor electron transfer between the enzyme active site and the electrode, and the like, which are the reasons of low energy density and power density. The graphene-based nano material has the unique characteristics of large specific surface area, high porosity, excellent conductivity, easiness in synthesis and functionalization and the like, provides an ideal immobilization place for biomolecules, can immobilize a large amount of enzymes, reduces leaching of the enzymes while wrapping the enzymes by a pore structure, prolongs the service life of the enzymes, and can be widely applied to biosensing and energy related applications.

Disclosure of Invention

Aiming at the development requirement of electrode materials of a biofuel cell, the invention provides a preparation method and application of a self-supporting substrate electrode with simple preparation process and low price.

In order to achieve the purpose, the invention adopts the technical scheme that: a self-supporting electrode substrate material is prepared by the following steps:

1) treating the pretreated carbon paper with strong acid;

2) taking carbon paper treated by strong acid as a working electrode, an Ag/AgCl electrode as a reference electrode and a platinum wire as a counter electrode, placing the three-electrode system in a potassium carbonate aqueous solution, and carrying out first-step electrochemical stripping;

3) taking the carbon paper electrochemically stripped in the first step as a working electrode, an Ag/AgCl electrode as a reference electrode and a platinum wire as a counter electrode, placing the three-electrode system in a phosphate buffer solution of potassium nitrate, and carrying out electrochemical stripping in the second step;

4) and (3) taking the carbon paper electrochemically stripped in the second step as a working electrode, an Ag/AgCl electrode as a reference electrode and a platinum wire as a counter electrode, placing the three-electrode system in a gold-containing solution, carrying out electrodeposition, depositing a layer of gold nanoparticles on the surface of the carbon paper, washing the obtained material with deionized water, and drying to obtain the self-supporting electrode substrate material with the three-dimensional structure.

Further, in the self-supporting electrode substrate material, in the step 1), the carbon paper is hydrophilic carbon paper.

Further, in the self-supporting electrode substrate material, the step 1) specifically comprises: uniformly mixing concentrated nitric acid and concentrated sulfuric acid according to the volume ratio of 3:1 to obtain a strong acid mixed solution, dropwise coating the strong acid mixed solution on the pretreated carbon paper, standing at room temperature for 5 minutes, and washing with deionized water to be neutral.

Further, in the self-supporting electrode base material, in the step 2), the concentration of the potassium carbonate aqueous solution is 0.5 mol/L; in the first step of electrochemical stripping process, the scanning potential is 0.5-1.8V, the number of scanning turns is 6, and the scanning rate is 20 mVs-1.

Further, in the self-supporting electrode substrate material according to the above, in step 3), in the phosphate buffer solution of potassium nitrate, the pH of the phosphate buffer solution is 7, and nitrate is addedThe concentration of potassium is 1 mol/L; in the second step of electrochemical stripping process, the scanning potential is-0.9-1.9V, the number of scanning cycles is 6, and the scanning rate is 20mV s^-1。

Further, in the self-supporting electrode substrate material, in the step 4), the gold-containing solution is a mixed solution of chloroauric acid and sulfuric acid, the electrodeposition voltage is-4V, and the electrodeposition time is 300 s.

A double-chamber enzyme biofuel cell based on self-supporting electrode substrate material is prepared by the following steps:

1) preparation of the biological anode: soaking the self-supporting electrode substrate material in a glucose oxidase solution at 4 ℃ overnight to obtain a biological anode;

2) preparing a biological cathode: dripping the paint enzyme dispersion liquid on the surface of the self-supporting electrode substrate material, and drying at room temperature to obtain a biological cathode;

3) preparing a double-chamber enzyme biofuel cell: the biological anode is used as an anode, the biological cathode is used as a cathode, two polar chambers are separated by a Nafion 211 membrane, PBS buffer solution with the pH value of 5 of glucose is filled in the anode chamber, HAc-NaAc buffer solution with the pH value of 5 saturated by oxygen is filled in the cathode chamber, and the double-chamber enzyme biofuel cell is formed.

Further, in the above-mentioned dual-chamber enzyme biofuel cell based on self-supporting electrode substrate material, in step 1), the concentration of the glucose oxidase solution is 5 mg/mL.

Further, in the above dual-chamber enzyme biofuel cell based on the self-supporting electrode substrate material, in step 2), the concentration of the laccase dispersion is 5 mg/mL.

Further, in the above two-chamber enzyme biofuel cell based on the self-supporting electrode substrate material, in step 3), the concentration of the PBS buffer solution with the pH of 5 of glucose is 60-100 mM.

The invention has the beneficial effects that:

1. the self-supporting electrode substrate material prepared by the invention has a stripped and layered three-dimensional structure, so that the self-supporting electrode substrate material has a larger specific surface area and a more uniform appearance, is favorable for being soaked by electrolyte and has strong conductivity.

2. The self-supporting electrode substrate material prepared by the invention adopts carbon paper as a material, has low cost and is environment-friendly and suitable for large-scale production.

3. When the self-supporting electrode substrate material prepared by the invention is applied to an enzyme biofuel cell, a large amount of enzyme can be loaded, the enzyme is not easy to inactivate and leach, and the power density is 17.66 mu W cm when the glucose concentration is 100mM^-2. The performance is hardly reduced after 7 days of repeated use in the cycling stability test, and the electrode material has the potential of becoming an excellent self-supporting electrode material.

Drawings

FIG. 1 is an SEM photograph of a self-supporting electrode base material prepared in example 1.

Fig. 2 is an XRD pattern of the self-supporting electrode base material prepared in example 1.

FIG. 3 is a graph of the results of a direct electrochemical test of glucose oxidase (GOx) on a self-supporting electrode substrate material prepared in example 1.

Fig. 4 is a graph of power density for dual-compartment enzyme biofuel cells (EBFCs) based on a self-supporting electrode substrate material.

Fig. 5 is a graph of the stability of a two-compartment enzyme biofuel cell based on self-supporting electrode substrate material for 7 days of power.

Detailed Description

The invention provides a preparation method of a self-supporting electrode substrate material and application of the self-supporting electrode substrate material in an enzyme biofuel cell, and the invention is further described by combining the embodiment and the attached drawings.

EXAMPLE 1 self-supporting electrode base Material

(I) preparation method

1. Carbon paper pretreatment and strong acid treatment

Pretreatment: cutting hydrophilic carbon paper into small pieces of 1.5 × 0.5cm, sequentially soaking in acetone, ethanol and deionized water, respectively performing ultrasonic treatment for 30 min, repeatedly cleaning with deionized water and ethanol, and oven drying.

Strong acid treatment: and (3) uniformly mixing the concentrated nitric acid and the concentrated sulfuric acid according to the volume ratio of 3:1 to obtain a strong acid mixed solution. And (3) dripping 20 mu L of strong acid mixed solution on the pretreated carbon paper, standing at room temperature for 5 minutes, washing with deionized water to be neutral, and drying for later use.

2. First step electrochemical stripping

The carbon paper treated by strong acid is used as a working electrode, an Ag/AgCl electrode is used as a reference electrode, a platinum wire is used as a counter electrode, and a three-electrode system is placed in electrolyte, wherein the electrolyte is 0.5M K₂CO₃The solution has a scanning potential of 0.5-1.8V, a number of scanning cycles of 6 and a scanning rate of 20mV s in the first electrochemical stripping process^-1. After finishing, washing with deionized water for 3-5 times, and soaking in deionized water overnight to completely remove excessive ions.

3. Second step electrochemical stripping

Taking the carbon paper electrochemically stripped in the first step as a working electrode, an Ag/AgCl electrode as a reference electrode, a platinum wire as a counter electrode, placing a three-electrode system in an electrolyte, wherein the electrolyte is a phosphate buffer solution of potassium nitrate, the pH value of the phosphate buffer solution is 7, the concentration of the potassium nitrate is 1mol/L, and in the electrochemical stripping process in the second step, the scanning potential is-0.9-1.9V, the number of scanning turns is 6, and the scanning speed is 20mV s^-1. And after finishing, repeatedly washing with deionized water and ethanol, removing inorganic residues, and drying to obtain the carbon paper HEG after two-step electrochemical stripping.

4. Electrodeposition

The carbon paper (HEG) stripped by secondary electrochemistry is taken as a working electrode, an Ag/AgCl electrode is taken as a reference electrode, a platinum wire is taken as a counter electrode, and the three-electrode system is placed in a gold-containing solution containing 5mM HAuCl₄0.5M H₂SO₄And electrodepositing the solution for 0-300s at a potential of-4V, depositing a layer of gold nanoparticles on the surface of the carbon paper, washing with deionized water, and drying to obtain the self-supporting electrode substrate material HEG-Au with a three-dimensional structure.

(II) detection

As shown in a of fig. 1, the carbon paper has been treated with strong acid, and the carbon paper has been significantly delaminated. As can be seen from B in FIG. 1, the self-supporting electrode substrate material obtained after the carbon paper is subjected to two-step electrochemical stripping and electrodeposition has a three-dimensional structure.

Fig. 2 is an XRD pattern of the prepared self-supporting electrode base material. As shown in fig. 2, the characteristic diffraction peak of the material at 26.3 ° is attributed to the (002) crystal plane of graphite. The characteristic diffraction peak of HEG-Au is consistent with that of standard card PDF-04-0784 of Au, and the successful loading of gold nanoparticles on carbon paper is proved.

Direct electrochemical behavior of glucose oxidase (GOx) on self-supporting electrode substrate materials

The biological catalytic activity of the electrode refers to the catalytic capability of the immobilized GOx on glucose and oxygen, and the direct electrochemical behavior of the GOx on the self-supporting electrode substrate material is researched by adopting cyclic voltammetry.

And soaking the prepared self-supporting electrode substrate in a glucose oxidase aqueous solution, and soaking in a temperature of 4 ℃ overnight to obtain the GOx modified electrode. The test is carried out at room temperature by using an electrochemical workstation, a three-electrode system is adopted for measurement during the test, the working electrode is a GOx modified electrode, the auxiliary electrode is a Pt sheet, the reference electrode is an Ag/AgCl electrode, the electrolyte is Phosphate Buffered Saline (PBS) with the pH value of 0.1M being 7, and the scanning speed is 0.05V s^-1The results are shown in FIG. 3, with high purity nitrogen sparge for 30 minutes prior to testing.

As shown in fig. 3, the electrodes loaded with GOx were tested for CV curves under nitrogen saturation (a), oxygen saturation (b), oxygen saturation and containing 0.1M glucose (c), respectively. When oxygen exists in the electrolyte, the oxidation peak current is greatly reduced, and the reduction peak current is greatly increased; the reduction current decreased and the oxidation current increased when glucose was added to the solution. These results indicate that the prepared GOx on the GOx modified electrode maintains biological activity. Furthermore, the sweep rate was 5mV s^-1The cathode peak current was approximately equal to the anode current by 30mV peak difference, indicating that quasi-reversible electrochemical processes occurred with GOx.

Example 2 Dual-chambered enzyme biofuel cell based on self-supporting electrode substrate material

The bioanode (HEG-Au/GOx) and biocathode (HEG-Au/lac) of this example were prepared by the following steps:

(I) preparation method

1. Preparation of bioanode

The self-supporting electrode substrate material prepared in example 1 is soaked in a glucose oxidase aqueous solution with the concentration of 5mg/mL and is placed in a temperature range of 4 ℃ for soaking overnight, and the bioanode HEG-Au/GOx is obtained.

2. Preparation of biocathodes

5mg/mL laccase dispersion liquid (laccase is uniformly dispersed in sodium acetate buffer solution with pH being 5) is dripped on the self-supporting electrode substrate material prepared in the example 1, and the self-supporting electrode substrate material is dried at room temperature to obtain the biocathode HEG-Au/lac.

3. Preparation of double-chamber enzyme biofuel cell

Using biological anode HEG-Au/GOx as anode, biological cathode HEG-Au/lac as cathode, separating two polar chambers by Nafion 211 membrane, filling PBS buffer solution with different concentrations of glucose and pH 5 into the anode chamber, filling HAc-NaAc buffer solution with oxygen saturation and pH 5 into the cathode chamber to form glucose/O₂The double-chamber enzyme biofuel cell.

(II) Performance testing

The performance passes the two electrode LSV test. The power output density of the cell versus cell voltage (P-V curve) is shown in fig. 4 when the cathode compartment is saturated with oxygen and the anode compartment has a glucose concentration of 0.1M. As can be seen from FIG. 4, the open circuit voltage and the maximum output power are 0.17V and 17.66. mu.W cm, respectively^-2。

(III) stability testing

For prepared glucose/O₂The stability of the dual-chamber enzyme biofuel cell was investigated.

The battery power density was measured every other day in a 0.1M glucose solution, and the test results are shown in fig. 5. As can be seen from fig. 5, after the constructed dual-chamber enzyme biofuel cell is repeatedly used for one day, the power can still reach 95.71% of the initial power, and after 7 days of repeated use, the power can still keep 81.68% of the original power, which indicates that the dual-chamber enzyme biofuel cell of the present invention has stable working performance and long service life.