CN113789543A

CN113789543A - Copper-based material with three-dimensional layered nano array structure and preparation method and application thereof

Info

Publication number: CN113789543A
Application number: CN202111181234.7A
Authority: CN
Inventors: 雷晓东; 金家兴; 葛静敏; 王一平
Original assignee: Beijing University of Chemical Technology
Current assignee: Beijing University of Chemical Technology
Priority date: 2021-10-11
Filing date: 2021-10-11
Publication date: 2021-12-14
Anticipated expiration: 2041-10-11
Also published as: CN113789543B

Abstract

The invention provides a copper-based material with a three-dimensional layered nano array structure, and a preparation method and application thereof₃P/CF electrode material. The preparation method is simple and easy to operate and has low cost. NiCuFeP @ Cu₃When the P/CF is used for an electrode for producing hydrogen by electrolyzing water, the overpotential of only 38-54mV can reach 10mA cm^‑2The current density of the material is not obviously reduced after 3000-circle cycle test, which shows that the material has excellent performance and good stability for electrocatalytic hydrogen production reaction.

Description

Copper-based material with three-dimensional layered nano array structure and preparation method and application thereof

The technical field is as follows:

the invention relates to an electrode material for hydrogen production by electrocatalysis electrolysis of water, in particular to a copper-based electrode material with a three-dimensional layered nano array structure, and a preparation method and application thereof.

Background art:

with the proposal of the global carbon neutralization concept, countries in the world have vigorously advocated low-carbon emission reduction, and clean energy has also received high attention. The hydrogen energy has the characteristics of cleanness, no pollution, reproducibility, high heat value and the like, and is considered to be onePromising alternatives to fossil energy. At present, the main hydrogen production technologies include fossil fuel reforming, photocatalytic hydrogen production, biomass hydrogen production, and hydrogen production by water electrolysis. Wherein, the hydrogen production by water electrolysis takes water as the only raw material, and the product realizes zero carbon emission, thus being the most green and sustainable method. Over the last decade, researchers have been seeking to develop electrocatalysts for the electrolysis of water to produce hydrogen. The results show that noble metal catalysts and their compounds (e.g., Pt, Ru, and RuO)₂Etc.) have the best hydrogen evolution performance, but their application is limited by high cost and low abundance. In recent years, many reports have been made on non-noble metal-based catalysts. Zhang et al [ Nanoscale,2020,12,23851]And Liu [ Inorg. chem.2019,58,11630-]Et al report Ni separately₂P-Cu₃P @ NiCuC two-dimensional nano array and Cu₃P-Ni₂P/NF two-dimensional nanostructure and at 10mA cm^-2At a current density of 106mV and 103mV overpotentials were achieved. However, the catalytic performance of these two electrode materials is not very good, and it is not suitable for practical production and life. Therefore, designing and synthesizing a series of hydrogen evolution electrocatalysts with low cost and high activity becomes a key point and a difficult point in the research of hydrogen production by water electrolysis.

The copper element is one of transition metal elements with abundant reserves and low price on the earth, and has excellent conductivity. Copper foam is an ideal conductive substrate for building multilayer structures in situ. It has an open network structure with interconnected macropores and can rapidly release hydrogen in the electrocatalytic reaction process. Electrocatalysts prepared on copper foam also typically have excellent mechanical strength, high electrical conductivity and large specific surface area. In addition, copper-based catalysts are widely used in the field of Hydrogen production by electrolysis of water due to their excellent conductivity and low cost, such as Adeel Afzal et al [ International Journal of Hydrogen Energy 45(2020)33396-33406]By adopting a simple annealing process, Ni-Cr is doped on a foam Copper (CF) substrate, and the electrocatalytic activity of the material Ni-Cr @ CF in a strong alkaline solution is explored, wherein the current density is 10mA cm^-2The overpotential was 144 mV. However, electrocatalytic materials based on amorphous transition metal phosphides of copper foam are rarely reported. As known, in phase with crystalline materialsIn contrast, amorphous materials expose more electrocatalytically active sites and exhibit higher electrocatalytic activity. Therefore, by combining the excellent characteristics of the copper foam and the advantages of the amorphous material, a three-dimensional layered amorphous nano-array structure is expected to be designed and synthesized, on one hand, the three-dimensional layered structure can expose larger active specific surface area and good stability, and on the other hand, the active sites can be greatly increased by loading the amorphous nano-structure, so that the catalytic performance of the material is improved.

The invention content is as follows:

the invention aims to provide an electrode material with a three-dimensional layered nano array structure and a preparation method thereof, and the material is used as an electrode material for hydrogen production reaction by water electrolysis.

The chemical formula of the three-dimensional layered nano array structure material is NiCuFeP @ Cu₃P/CF, wherein CF represents a copper substrate, Cu₃P attachment to CF forms Cu₃P/CF，Cu₃P is a nanowire array structure; NiCuFeP loaded in Cu₃P is formed into NiCuFeP @ Cu₃The P/CF three-layer structure, wherein NiCuFeP is an amorphous nano-sheet structure, the size of the nano-sheet is 120-140nm, and the thickness is 5-10 nm. The material has excellent hydrogen evolution performance of electrocatalysis electrolysis water.

The preparation method of the three-dimensional layered nano array structure material comprises the steps of taking foam copper as a substrate, and firstly carrying out chemical immersion on Cu (OH)₂Growing in-situ on a foam copper substrate, and then carrying out chemical vapor deposition on Cu (OH)₂Low temperature phosphating to form Cu₃A P nanowire array; then Cu₃P/CF is a secondary substrate, and NiCuFeP is loaded on Cu by an electrochemical deposition method₃On the P nanowire, NiCuFeP is in an amorphous nanosheet structure.

The invention relates to a three-dimensional layered nano array structure NiCuFeP @ Cu₃The preparation method of the P/CF material comprises the following specific steps:

A. preparing a mixed solution of sodium hydroxide and ammonium persulfate, wherein the concentration of the sodium hydroxide is 2.0-3.0mol L^-1The concentration of ammonium persulfate is 0.05-0.15mol L^-1(ii) a Placing the pretreated foam copper substrate into the mixed solution, standing for 30min at normal temperature,taking out, alternately washing with deionized water and absolute ethyl alcohol, drying at 40-80 deg.C to obtain Cu (OH) grown in situ on copper substrate₂Nanowire array Material, denoted Cu (OH)₂/CF。

The method for pretreating the foam copper substrate comprises the steps of cutting the foam copper into pieces with proper sizes, and using absolute ethyl alcohol and 1-2mol L of^-1Sequentially performing ultrasonic treatment on the hydrochloric acid solution and deionized water for 5-15min, taking out, and cleaning for later use.

B. In a tube furnace, the Cu (OH) obtained in step A₂the/CF is placed at the lower end of the quartz tube, the sodium hypophosphite is placed at the upper end, and the temperature is 1-3 ℃ min in a nitrogen atmosphere of 40-50sccm^-1Heating rate to 250-270 ℃ for 1-2h, Cu (OH)₂Low temperature phosphating to form Cu₃P to Cu₃P/CF；Cu₃P is a nanowire array structure.

The dosage of the sodium hypophosphite is 0.08 to 0.1g of phosphorus source per square centimeter of copper hydroxide.

C. Using a three-electrode system with Cu₃P/CF is a working electrode, a Pt electrode is a counter electrode, an Ag/AgCl electrode is a reference electrode, the electrolyte is a mixed electrolyte composed of nickel nitrate, ferrous sulfate, copper sulfate, sodium hypophosphite and ammonium fluoride, and the NiCuFeP @ Cu is obtained by electrodeposition for 30-40min under the constant voltage of 1.0-2.0V (vs. Ag/AgCl)₃P/CF, wherein NiCuFeP is in an amorphous nanosheet structure.

Ni in the mixed electrolyte²⁺:Fe²⁺:Cu²⁺:NH₄F:NaH₂PO₂The concentration ratio of (A) to (B) is 2:1-2:2-3:35-40:40-45, wherein Ni²⁺The concentration of (B) is 0.70-0.80mmol L^-1。

Characterization and application experiments

FIG. 1 is a NiCuFeP @ Cu sample prepared in example 1₃Scanning Electron Microscope (SEM) characterization of P/CF, it can be seen that NiCuFeP nanosheets grow uniformly in Cu₃On the P nanowire array, the size of the nanosheet is 120-140nm, and the thickness is 5-10 nm.

FIG. 2 is a NiCuFeP @ Cu sample prepared in example 1₃High Resolution Transmission Electron Microscopy (HRTEM) characterization of P/CF by imageAs can be seen, the NiCuFeP nanosheets have no lattice stripes, and Cu is detected₃Lattice spacing on P nanowires of 0.201nm, corresponding to (300) plane, NiCuFeP nanoplate and Cu₃There are significant limitations to P nanowires.

FIG. 3 is a NiCuFeP @ Cu sample prepared in example 1₃The X-ray diffraction (XRD) pattern of P/CF is shown, and no other phosphide peaks except the strong peak of the foamed copper substrate indicate that the NiCuFeP grown on the surface is in an amorphous structure.

FIG. 4 is a NiCuFeP @ Cu sample prepared in example 1₃An X-ray photoelectron spectroscopy (XPS) graph of the P/CF shows that phosphide characteristic peaks appear in the graphs corresponding to all elements, which indicates that the phosphorization is successful.

FIG. 5 is NiCuFeP @ Cu prepared as in example 1₃P/CF is 1.0mol L of electrode^-1In the potassium hydroxide electrolyte, under the condition of nitrogen saturation, the current density reaches 10mA cm^-2The overpotential is only 38mV, which shows that the material has excellent electrocatalytic performance.

FIG. 6 is NiCuFeP @ Cu prepared as in example 1₃P/CF is 1.0mol L of electrode^-1In the potassium hydroxide electrolyte, under the nitrogen saturation condition, the Tafel slope curve is only 96.8mA dec^-1The material can effectively catalyze and electrolyze water to produce hydrogen.

FIG. 7 is NiCuFeP @ Cu prepared as in example 1₃The P/CF is a relation curve of the scanning speed of the electrode at different scanning speeds of 0.03-0.07V and the current density. Calculated to obtain the NiCuFeP @ Cu₃Electric double layer capacitance C of P/CF electrode_dIIs 71.16mF cm^-1Description of NiCuFeP @ Cu₃The electrochemical active surface area of the P/CF is larger, which is beneficial to the implementation of hydrogen production reaction by electrocatalysis water electrolysis.

FIG. 8 is NiCuFeP @ Cu prepared as in example 1₃P/CF is 1mol L of electrode^-1Cycling stability profile in potassium hydroxide electrolyte. As can be seen from the figure, the overpotential is kept low after 3000 cycles, and the catalytic performance is not obviously changed, which shows that the material has good stability and meets the production requirement of the actual electrocatalysis water electrolysis hydrogen production.

FIG. 9 is NiCuFeP @ Cu prepared as in example 2₃P/CF is 1.0mol L of electrode^-1Time-current curve in potassium hydroxide electrolyte. As can be seen from the figure, the current density is not obviously attenuated during the process, the catalytic performance is kept good, and the material has long-term stability and can be used for practical production application.

The invention has the beneficial effects that:

the invention adopts a chemical immersion method to grow Cu (OH) in situ on a foam copper substrate₂Nanowire array, and then carrying out low-temperature phosphorization by a chemical vapor deposition method to obtain Cu₃Growing an amorphous NiCuFeP nanosheet by an electrochemical deposition method, and loading a nickel-copper-iron phosphide nanosheet on the premise of keeping the structure of the cuprous phosphide nanowire array to obtain NiCuFeP @ Cu nanosheet with a unique structure₃P/CF. The preparation method of the material is simple and easy to operate, low in cost, large in electrochemical active surface area and strong in conductivity. NiCuFeP @ Cu₃When the P/CF is used for an electrode for producing hydrogen by electrolyzing water, the overpotential of only 38-54mV can reach 10mA cm^-2The current density of the material is not obviously reduced after 3000-circle cycle test, which shows that the material has excellent performance and good stability for electrocatalytic hydrogen production reaction.

Drawings

FIG. 1 is a NiCuFeP @ Cu sample prepared in example 1₃Scanning Electron Microscope (SEM) characterization of P/CF.

FIG. 2 is a NiCuFeP @ Cu sample prepared in example 1₃High Resolution Transmission Electron Microscopy (HRTEM) characterization of P/CF.

FIG. 3 is a NiCuFeP @ Cu sample prepared in example 1₃X-ray diffraction (XRD) characterization of P/CF.

FIG. 4 is a NiCuFeP @ Cu sample prepared in example 1₃X-ray photoelectron spectroscopy (XPS) characterization of P/CF.

FIG. 5 is a NiCuFeP @ Cu sample prepared in example 1₃Linear voltammetric scan curves of P/CF.

FIG. 6 is a NiCuFeP @ Cu sample prepared in example 1₃Tafel slope curve for P/CF electrode.

FIG. 7 is an embodimentNiCuFeP @ Cu prepared in example 1₃The scanning speed of the P/CF electrode under different scanning speeds is plotted against the current density.

FIG. 8 is a NiCuFeP @ Cu sample prepared in example 1₃Cycling stability curves for P/CF electrodes.

FIG. 9 is a NiCuFeP @ Cu sample prepared in example 2₃Time-current curve for P/CF electrode.

Detailed Description

Example 1

A. Pretreatment of the copper foam: cutting commercially available copper foam with thickness of 0.5mm into 3.0 cm/2.0 cm pieces, ultrasonically cleaning with anhydrous ethanol for 5min, and then washing with 1.0mol L^-1Performing ultrasonic treatment on the hydrochloric acid solution for 10min, finally performing ultrasonic cleaning on the hydrochloric acid solution by using deionized water, and drying the hydrochloric acid solution in a 60 ℃ drying oven for later use.

B. Weighing 4g of sodium hydroxide and 1.14g of ammonium persulfate, dissolving in 50mL of deionized water continuously introduced with nitrogen to prepare a mixed solution, wherein the molar concentrations of the sodium hydroxide and the ammonium persulfate are respectively 2mol L^-1，0.1mol L^-1. Placing the foam copper substrate pretreated in the step A in the mixed solution, keeping the temperature at 30 ℃ for 30min, taking out, washing with deionized water, and drying in an oven at 60 ℃ to obtain Cu (OH)₂/CF。

C. Weighing 1g of sodium hypophosphite, placing the sodium hypophosphite in a porcelain boat, and placing the porcelain boat at the upper end of a quartz tube, namely, enabling air flow to flow upwards; the Cu (OH) obtained in the step B₂the/CF is also placed in the porcelain boat and at the lower end of the quartz tube, namely, the gas flow flows downwards. At 1 deg.C for min in a nitrogen atmosphere of 50sccm^-1Calcining at 270 ℃ for 1h, cooling to room temperature and taking out for later use to obtain Cu₃P/CF。

D. 0.22g of nickel nitrate, 0.42g of ferrous sulfate, 0.09g of copper sulfate, 3.72g of sodium hypophosphite and 1.0g of ammonium fluoride are weighed and dissolved in 50mL of deionized water continuously introduced with nitrogen to prepare a mixed electrolyte, wherein the concentration of the nickel nitrate, the ferrous sulfate, the copper sulfate, the sodium hypophosphite and the ammonium fluoride is 0.77mmol L^-1、1.50mmol L^-1、0.385mmol L^-1、31mmol L^-1And 27mmol L^-1. C, adopting a three-electrode system, and mixing the Cu obtained in the step C₃P/CF is used as a working electrode, a Pt electrode is used as a counter electrode, an Ag/AgCl electrode is used as a reference electrode, electrodeposition is carried out for 30min under the constant voltage of 1.2V (vs. Ag/AgCl), deionized water is used for washing, and the amorphous NiCuFeP @ Cu is obtained by drying in a 60 ℃ oven₃P/CF。

Example 2

A. The same as in example 1.

B. The same as in example 1.

C. Weighing 0.5g of sodium hypophosphite, placing the sodium hypophosphite in a porcelain boat, and placing the porcelain boat at the upper end of a quartz tube, namely, upstream flowing of airflow; the Cu (OH) obtained in the step B₂the/CF is also placed in the porcelain boat and at the lower end of the quartz tube, namely, the gas flow flows downwards. At 2 deg.C for min in a nitrogen atmosphere of 50sccm^-1Calcining at 250 ℃ for 1h, cooling to room temperature and taking out for later use to obtain Cu₃P/CF。

D. The same as in example 1.

Example 3

A. The same as in example 1.

B. The same as in example 1.

C. The same as in example 1.

D. 0.11g of nickel nitrate, 0.21g of ferrous sulfate, 0.045g of copper sulfate, 1.86g of sodium hypophosphite and 0.5g of ammonium fluoride are weighed and dissolved in 50mL of deionized water continuously introduced with nitrogen to prepare a mixed electrolyte, wherein the concentration of the nickel nitrate, the ferrous sulfate, the copper sulfate, the sodium hypophosphite and the ammonium fluoride is 0.385mmol L^-1、0.75mmol L^-1、0.19mmol L^-1、15.5mmol L^-1And 13.5mmol L^-1. C, adopting a three-electrode system, and mixing the Cu obtained in the step C₃P/CF is used as a working electrode, a Pt electrode is used as a counter electrode, an Ag/AgCl electrode is used as a reference electrode, electrodeposition is carried out for 40min under the constant voltage of 1.5V (vs. Ag/AgCl), deionized water is used for washing, and the amorphous NiCuFeP @ Cu is obtained by drying in a 60 ℃ oven₃P/CF。

Example 4

A. The same as in example 1.

B. The same as in example 1.

C. Weighing 1.5g of sodium hypophosphite, placing the sodium hypophosphite in a porcelain boat, and placing the porcelain boat at the upper end of a quartz tube, namely, upstream flowing of airflow; the Cu (OH) obtained in the step B₂the/CF is also placed in the porcelain boat and at the lower end of the quartz tube, namely, the gas flow flows downwards. Under a nitrogen atmosphere of 40sccm at 2 ℃ for min^-1Calcining at 260 ℃ for 2h, cooling to room temperature and taking out for later use to obtain Cu₃P/CF。

D. 0.44g of nickel nitrate, 0.82g of ferrous sulfate, 0.18g of copper sulfate, 6.54g of sodium hypophosphite and 2.0g of ammonium fluoride are weighed and dissolved in 50mL of deionized water continuously introduced with nitrogen to prepare a mixed electrolyte, wherein the concentration of the nickel nitrate, the ferrous sulfate, the copper sulfate, the sodium hypophosphite and the ammonium fluoride is 1.54mmol L^-1、3.0mmol L^-1、0.77mmol L^-1、62mmol L^-1And 54mmol L^-1. C, adopting a three-electrode system, and mixing the Cu obtained in the step C₃P/CF is used as a working electrode, a Pt electrode is used as a counter electrode, an Ag/AgCl electrode is used as a reference electrode, electrodeposition is carried out for 30min under the constant voltage of 1.0V (vs. Ag/AgCl), deionized water is used for washing, and the amorphous NiCuFeP @ Cu is obtained by drying in a 60 ℃ oven₃P/CF。

Claims

1. A preparation method of a copper-based material with a three-dimensional layered nano array structure is characterized by comprising the following specific preparation steps:

A. preparing a mixed solution of sodium hydroxide and ammonium persulfate, wherein the concentration of the sodium hydroxide is 2.0-3.0mol L^-1The concentration of ammonium persulfate is 0.05-0.15mol L^-1(ii) a Placing the pretreated foam copper substrate into the mixed solution, standing at normal temperature for 30min, taking out, alternately washing with deionized water and absolute ethyl alcohol, and drying at 40-80 deg.C to obtain Cu (OH) growing in situ on the copper substrate₂Nanowire array Material, denoted Cu (OH)₂/CF；

The pretreatment method of the foam copper substrate comprises the steps of cutting the foam copper into pieces with proper sizes, and using absolute ethyl alcohol and 1-2mol L^-1Sequentially performing ultrasonic treatment on the hydrochloric acid solution and deionized water for 5-15min, taking out, and cleaning for later use;

B. in a tube furnace, the Cu (OH) obtained in step A₂the/CF is placed at the lower end of the quartz tube, the sodium hypophosphite is placed at the upper end, and the temperature is 1-3 ℃ min in a nitrogen atmosphere of 40-50sccm^-1Heating rate ofHeating to 250-270 ℃ for 1-2h, Cu (OH)₂Low temperature phosphating to form Cu₃P to Cu₃P/CF；Cu₃P is a nanowire array structure;

the dosage of the sodium hypophosphite is 0.08 to 0.1g of phosphorus source corresponding to each square centimeter of copper hydroxide;

C. using a three-electrode system with Cu₃P/CF is a working electrode, a Pt electrode is a counter electrode, an Ag/AgCl electrode is a reference electrode, the electrolyte is a mixed electrolyte composed of nickel nitrate, ferrous sulfate, copper sulfate, sodium hypophosphite and ammonium fluoride, and the NiCuFeP @ Cu is obtained by electrodeposition for 30-40min under the constant voltage of 1.0-2.0V (vs. Ag/AgCl)₃P/CF, wherein NiCuFeP is in an amorphous nanosheet structure;

2. The copper-based material with the three-dimensional layered nano-array structure prepared by the method of claim 1, wherein the chemical formula of the copper-based material is NiCuFeP @ Cu₃P/CF, wherein CF represents a copper substrate, Cu₃P attachment to CF forms Cu₃P/CF，Cu₃P is a nanowire array structure; NiCuFeP loaded in Cu₃P is formed into NiCuFeP @ Cu₃The P/CF three-layer structure, wherein NiCuFeP is an amorphous nano-sheet structure, the size of the nano-sheet is 120-140nm, and the thickness is 5-10 nm.

3. Use of the copper-based material with the three-dimensional layered nano-array structure according to claim 2 as an electrode material for hydrogen production reaction by water electrolysis.