阅读说明：本技术 一种高性能镍铁基析氧电催化纳米复合材料及其制备方法与应用 (High-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite and preparation method and application thereof ) 是由 周炎 郭千瑜 张军 王雪媛 王淑涛 脱永笑 贾翠萍 于 2020-06-28 设计创作，主要内容包括：本发明涉及一种高性能镍铁基析氧电催化纳米复合材料及其制备方法与应用,该复合材料是由四硫化三镍和二硫化铁相互交联的均匀纳米片组成。该复合材料含有高价态金属离子Ni<Sup>3+</Sup>,增加了OER的活性位点,同时增强了镍铁之间的协调作用,进一步提高了电催化性能。用简单水热法合成的镍铁基析氧电催化纳米复合材料,具有制备工艺简单、高效、合成条件温和、对环境友好等优点,且具有较高的催化活性,良好的电化学稳定性,适用于电化学领域,具有较大的潜在实用价值。(The invention relates to a high-performance nickel-iron-based oxygen evolution electrocatalytic nano composite material and a preparation method and application thereof. The composite material contains high valence metal ions Ni 3+ The active sites of OER are increased, the coordination effect between ferronickel is enhanced, and the electrocatalysis performance is further improved. The nickel-iron-based oxygen evolution electrocatalytic nanocomposite synthesized by the simple hydrothermal method has the advantages of simple preparation process, high efficiency, mild synthesis conditions, environmental friendliness and the like, has high catalytic activity and good electrochemical stability, is suitable for the electrochemical field, and has great potential practical value.)

1. A high-performance nickel-iron-based oxygen evolution electrocatalytic nano composite material is characterized in that the material is Ni₃S₄/FeS₂The composite material has a uniform nano-sheet structure which is cross-linked with each other, and the size of the composite material is 200-300 nm.

2. The high performance nickel-iron based oxygen evolution electrocatalytic nanocomposite as claimed in claim 1, wherein said Ni is selected from the group consisting of Ni, fe, Ni₃S₄/FeS₂Ni in composite materials₃S₄：FeS₂＝(1-4)：1。

3. The high performance nickel-iron based oxygen evolution electrocatalytic nanocomposite as claimed in claim 1, wherein said Ni is selected from the group consisting of Ni, fe, Ni₃S₄/FeS₂In the nano composite materialLattice distance corresponding to Ni₃S₄(440)、FeS₂(200)、FeS₂(222)；

Preferably, said Ni₃S₄/FeS₂The regio-electron diffraction (SAED) mode of the composite showed clear diffraction spots, corresponding to Ni₃S₄(444)、Ni₃S₄(531)、Ni₃S₄(311)、FeS₂(511)、FeS₂(210)；

Preferably, said Ni₃S₄/FeS₂The diffraction patterns of X-ray diffraction (XRD) of the composite materials respectively correspond to Ni₃S₄(JCPDF:24-1739) and FeS₂(JCPDF:01-1295)；

Preferably, the X-ray photoelectron spectrum of the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite shows peaks containing five components of C1S, O1S, Ni2p, Fe2p and S2 p.

4. The method for preparing the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite material as claimed in claim 1, comprising the steps of:

(1) dissolving an iron source and a nickel source in a solvent in an alkaline environment, uniformly stirring, and carrying out hydrothermal reaction in a high-pressure kettle to obtain a primary product;

(2) further sulfurizing the obtained primary product through hydrothermal reaction, washing and drying the product to obtain the high-performance Ni₃S₄/FeS₂An oxygen evolution electrocatalytic material.

5. The method for preparing the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite as claimed in claim 4, wherein the iron source in the step (1) is ferric nitrate, the nickel source is nickel nitrate, and the sulfur source is sodium sulfide.

6. The method for preparing the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite as claimed in claim 4, wherein the alkaline environment in the step (1) is provided by urea, and the adding amount of the urea is controlled in a range of 1: (4-6).

7. The method for preparing the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite as claimed in claim 4, wherein the ratio of the nickel source to the iron source in the step (1) is controlled to be n in terms of the molar ratio of the iron element to the nickel element_Ni：n_Fe＝(5-10):1。

8. The preparation method of the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite material as claimed in claim 4, wherein the hydrothermal reaction temperature in the step (1) is 120 ℃, and the hydrothermal reaction time is 6 h; the hydrothermal reaction temperature in the step (2) is 90 ℃, and the hydrothermal reaction time is 9 h.

9. The method for preparing the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite as claimed in claim 4, wherein the amount of the sulfur source added in the step (2) is controlled to be 1: (8-11).

10. Use of the high performance nickel-iron based oxygen evolution electrocatalytic nanocomposite material as claimed in claim 1 in electrolytic aquatic oxygen production reactions.

Technical Field

The invention relates to the field of new material technology and electrocatalysis, and belongs to the fields of polymer chemistry and nano materials. In particular to a nickel-iron-based oxygen evolution electro-catalytic material and a synthesis method thereof, and a nickel-iron-based oxygen evolution electro-catalyst (Ni) synthesized by the material₃S₄/FeS₂) Has good electrochemical performance.

Background

In the modern society, environmental pollution caused by the dependence on fossil energy, greenhouse effect and energy crisis have attracted extensive attention all over the world, so that the development of a more green new energy technology becomes one of the problems which people need to solve urgently. The hydrogen energy has the advantages of large energy, small density, various forms, convenient transportation, reproducibility, no pollution and the like, and is considered as an ideal alternative energy for fundamentally solving global problems of energy, environment and the like. The hydrogen production by electrolyzing water is the most promising hydrogen production technology because of abundant raw material reserves and zero carbon emission. However, the kinetics in the Oxygen Evolution Reaction (OER) are slow and the higher overpotential is the main cause of the water electrolysis efficiency. Therefore, the search for a catalyst with abundant mineral resources, low price and high catalytic efficiency still faces the main challenge.

Transition metals (such as Ni, Co, Fe, etc.) have attracted more and more research interests of researchers due to the abundance and considerable activity of the earth. In recent years, a large number of highly active, corrosion-resistant transition metal composite nanomaterials (sulfides, carbides, nitrides and phosphides) have been developed on earth, which can well replace noble metals as catalysts in electrochemical water splitting. Among them, iron (nickel) sulfide has the advantages of good electrocatalytic activity, good conductivity, easy synthesis, controllable structure and morphology, etc. and is widely used as an excellent catalyst for OER. The related bimetallic catalysts, particularly nickel iron based compounds, are more attractive than the single metal catalysts and are one of the most promising candidates.

However, their electrochemical applications are also subject to some severityFor example, the higher valence metal ion content is low. Higher valent metal ions such as Ni³⁺Has been found to be the active site identified as OER, and most work has been focused on Ni²⁺A base material. Meanwhile, in the preparation process of the iron (nickel) sulfide nano composite material, due to the defect of control of preparation process parameters, the traditional electrocatalytic composite material has the problems of nonuniform appearance, easy accumulation and the like, and the oxygen evolution performance of the traditional electrocatalytic composite material is deficient due to the obstruction of electron transmission and active site exposure. Therefore, the preparation of the nickel-iron-based nano material containing high-valence metal ions and having a uniform morphology for application in electrocatalytic oxygen evolution is a problem to be solved urgently. The invention is therefore proposed.

Disclosure of Invention

Aiming at the defects and shortcomings in the prior art, the invention provides a high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite, wherein high-valence metal ions increase the active sites of OER, and the coordination effect between nickel and iron improves the electrocatalytic performance. The nickel-iron-based nano composite material is synthesized by a hydrothermal method, the preparation method is simple in process, efficient, mild in synthesis conditions, rich in raw material source and low in cost, and the prepared electro-catalytic material shows good electrochemical performance as an electrochemical oxygen production catalyst.

The invention also provides a preparation method of the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite and application of the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite in electrocatalytic oxygen evolution.

The technical scheme of the invention is as follows:

a high-performance Ni-Fe-based oxygen evolution electrocatalytic nano composite material is Ni₃S₄/FeS₂The composite material has a uniform nano-sheet structure which is cross-linked with each other, and the size of the composite material is 200-300 nm.

According to the invention, preferably, said Ni₃S₄/FeS₂Ni in composite materials₃S₄：FeS₂(1-4): 1, further preferably (1.5-3.5): 1, most preferably 3:1, molar ratio. Said Ni₃S₄/FeS₂Ni in composite materials₃S₄：FeS₂3:1 (ferronickel mol)The molar ratio of 9:1) is optimal, and the material has long-term stability.

According to the invention, preferably, said Ni₃S₄/FeS₂Lattice distance in the nanocomposite corresponds to Ni₃S₄(440)、FeS₂(200)、FeS₂(222)。

According to the invention, preferably, said Ni₃S₄/FeS₂The regio-electron diffraction (SAED) mode of the composite showed clear diffraction spots, corresponding to Ni₃S₄(444)、Ni₃S₄(531)、Ni₃S₄(311)、FeS₂(511)、FeS₂(210)。

According to the invention, preferably, said Ni₃S₄/FeS₂The diffraction patterns of X-ray diffraction (XRD) of the composite materials respectively correspond to Ni₃S₄(JCPDF:24-1739) and FeS₂(JCPDF:01-1295)。

According to the invention, preferably, the X-ray photoelectron spectrum of the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite shows peaks containing five components of C1S, O1S, Ni2p, Fe2p and S2 p. In the Ni2P region, two main peaks are respectively located at 856.27eV and 873.85eV, which correspond to Ni2P_3/2And Ni2P_1/2，Ni2p_3/2The peaks can be further fitted such that the two peaks 855.89eV and 857.32eV correspond to Ni, respectively²⁺And Ni³⁺,Ni2p_1/2The peaks can be further fitted such that the two peaks 873.46eV and 875.18eV correspond to Ni, respectively²⁺And Ni³⁺Two satellite peaks appear at 861.89eV and 880.01 eV; in the Fe2p region, two main peaks are respectively located at 856.27eV and 873.85eV, which correspond to Fe2P_3/2And Fe2P_1/2Is Fe²⁺Peak at 713.20eV corresponding to Fe³⁺It is likely that there is partial oxidation of the sample, with two satellite peaks at 717.85eV and 734.80 eV; in the region of S2p, the peaks at 161.05eV, 161.99eV and 163.25eV are assigned to S2p_3/2、S2p_1/2And S₂ ^2-。

According to the invention, the preparation method of the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite comprises the following steps:

(1) dissolving an iron source and a nickel source in a solvent in an alkaline environment, uniformly stirring, and carrying out hydrothermal reaction in a high-pressure kettle to obtain a primary product;

(2) further sulfurizing the obtained primary product through hydrothermal reaction, washing and drying the product to obtain the high-performance Ni₃S₄/FeS₂An oxygen evolution electrocatalytic material.

According to the invention, preferably, the iron source in the step (1) is ferric nitrate, the nickel source is nickel nitrate, the sulfur source is sodium sulfide, and the hydrothermal reaction is carried out in a polytetrafluoroethylene high-pressure reaction kettle.

According to the present invention, preferably, the alkaline environment in step (1) is provided by urea, and the addition amount of urea is controlled in a range of 1: (4-6), most preferably 1: 5.

According to the present invention, it is preferable that the ratio of the nickel source to the iron source in the step (1) is controlled to n in terms of the molar ratio of the iron element to the nickel element_Ni：n_Fe1, more preferably (8-9): 1.

according to the invention, preferably, in the step (1), the hydrothermal reaction temperature is 120 ℃, and the hydrothermal reaction time is 6 h; the hydrothermal reaction temperature in the step (2) is 90 ℃, and the hydrothermal reaction time is 9 h.

According to the invention, it is preferred that the primary product in step (1) is further pretreated, and the pretreatment is as follows: the primary product was washed with ethanol and water three times in sequence and dried in a vacuum oven at 60 ℃.

According to the present invention, it is preferable that the amount of the sulfur source added in step (2) is controlled to be 1: (8-11), most preferably 1: 10.

According to the present invention, it is preferable that the Ni is obtained by cooling to room temperature after the completion of the reaction, centrifugal washing, and drying₃S₄/FeS₂Electrocatalytic oxygen evolution nanocomposite.

The invention also provides application of the high-performance nickel-iron-based oxygen evolution electro-catalysis nano composite material in oxygen production reaction by electrolysis of water.

Testing Ni on an electrochemical workstation using a standard three-electrode system₃S₄/FeS₂The oxygen production capacity of water decomposed by electrocatalysis is tested as follows:

dispersing 5mg of catalyst sample into 500. mu.l of ethanol at room temperature, adding 20. mu.l of Nafion solution, performing ultrasonic treatment for 30min to form a uniform solution, and then dropwise adding 100. mu.l of the mixed solution into pretreated carbon paper with a loading concentration of 1mg/cm²As the working electrode.

The polarization curve (LSV) and cyclic voltammetry Curve (CV) were tested in a 1M KOH solution using a CHI660 electrochemical workstation, using Ag/AgCl (in 3M KCl) as a reference electrode and a graphite electrode as a counter electrode, and the electrolyte was deoxygenated by introducing inert gas (nitrogen, argon, etc.) for 30min before each experiment, eliminating interference, and the sweep rate was set at 5 mV. s^-1。

The alternating current impedance (EIS) was tested with the CHI660 electrochemical workstation, keeping the other test conditions the same, with the potential parameter set at 0.48V (relative to the Ag/AgCl electrode) and the frequency set from 100000Hz to 0.01 Hz.

The overpotential (eta) to log (j) is used for obtaining a tafel curve, and then the dynamic performance of the electrocatalytic oxygen generation of the catalyst is evaluated through the solved tafel slope.

All potential values in the experiment are corrected by a standard hydrogen electrode, and an electrode potential calibration equation is an equation:

E_RHE＝E_Ag/AgCl+0.059PH+E⁰ _Ag/AgCl(E⁰ _Ag/AgCl＝0.198V)

compared with the prior art, the invention has the following advantages:

1. the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite prepared by the invention has the advantages of easily available and cheap raw materials and simple and mild preparation conditions. The material is rich in high valence metal ion Ni³⁺The chemical adsorption of OH is enhanced, and the electron transfer is promoted. The related bimetallic catalysts, particularly nickel iron based catalysts, are more attractive than the single metal catalysts. The synergistic effect between Ni and Fe in the material, special electronic structure and uniform appearance, and can accelerate the electron transmission rate to make the material possess excellent propertiesIt has higher OER catalytic activity and electrochemical stability.

2. The invention finds that through the performance test of the linear scanning curve: the nickel-iron-based electrocatalytic nanocomposite material composed of uniform nanosheets has excellent oxygen evolution performance, particularly with nickel tetrasulfide (Ni)₃S₄) Commercial catalyst ruthenium oxide (RuO)₂) Compared with the prior art, the method can realize high efficiency and high capacity of oxygen evolution in the electrocatalysis process under the same current density, thereby having higher application value in the electrocatalysis hydrogen evolution. Has long-term stability and current density of 50mA cm^-2The overpotential only needs 252 mV.

Drawings

FIG. 1 shows Ni prepared in example 1₃S₄A transmission electron microscope picture;

FIG. 2 is a transmission electron microscope photograph of the nickel-iron based electrocatalytic nanocomposite prepared in example 2;

FIG. 3 shows Ni prepared in example 2₃S₄/FeS₂High resolution transmission electron microscopy pictures of nanocomposites;

FIG. 4 shows Ni prepared in example 2₃S₄/FeS₂A selected area electron diffraction picture of the nanocomposite;

FIG. 5 shows Ni prepared in example 2₃S₄/FeS₂Scanning electron microscope pictures of the nanocomposite;

fig. 6 is a XRD contrast picture of the nickel-iron based electrocatalytic nanocomposite prepared in example 1 and example 2;

FIG. 7 is the X-ray photoelectron spectrum (a) and the high-resolution spectra of Ni2p (b), Fe2p (c) and S2p (d) of the nickel-iron-based electrocatalytic nanocomposite obtained in example 2;

FIG. 8 shows Ni obtained in example 2₃S₄/FeS₂The graph of the oxygen evolution performance test of the nano composite material is a linear scanning curve, (b) a cyclic voltammetry curve under different scanning speeds, (c) an alternating current impedance curve, (d) a tafel curve, (e) 100mA cm^-2Testing the stability of constant current under current density;

FIG. 9 is a comparison XRD picture of the nickel iron based electrocatalytic nanocomposite prepared in example 2 and comparative examples 1-3;

FIG. 10 is a graph of electrocatalytic oxygen generation linear sweep voltammograms of the nickel-iron based electrocatalytic materials prepared in examples 1-2 and comparative examples 1-3.

Detailed Description

The method for preparing the high-performance nickel-iron-based oxygen evolution electrocatalytic nanocomposite material according to the present invention is described in detail below with reference to the specific embodiments and examples.