CN114250486A

CN114250486A - Preparation method of surface nano-porous NiMoCu catalyst

Info

Publication number: CN114250486A
Application number: CN202210063882.0A
Authority: CN
Inventors: 葛性波; 晏莎莎; 梁梓灏; 兰高力; 易洪亮; 李玲; 张红
Original assignee: Southwest Petroleum University
Current assignee: Southwest Petroleum University
Priority date: 2022-01-20
Filing date: 2022-01-20
Publication date: 2022-03-29
Anticipated expiration: 2042-01-20
Also published as: CN114250486B

Abstract

The invention provides a method for preparingA preparation method of a surface nano-porous NiMoCu catalyst applied to hydrogen production by electrolyzing water belongs to the technical field of catalyst material preparation. Firstly, preparing Ni by using an electric arc melting technology₇₄Mo₆Cu₂₀And preparing the surface nano-porous NiMoCu catalyst by adopting an electrochemical etching method on the basis of the master alloy strip. The NiMoCu catalyst prepared by the invention shows good HER catalytic activity in an alkaline medium, and obtains a spongy nanoporous microstructure after etching, so that the specific surface area of activity is optimized, more active sites are exposed, and the aim of improving the activity of the catalyst is fulfilled. Meanwhile, the preparation process is simple, the raw materials are rich and cheap, and the catalyst can replace expensive and scarce noble metal-based catalyst, so that the commercial application of hydrogen production by water electrolysis is promoted.

Description

Preparation method of surface nano-porous NiMoCu catalyst

Technical Field

The invention relates to the technical field of catalyst material preparation, and provides a preparation method of a surface nano-porous NiMoCu catalyst which can be applied to hydrogen production by water electrolysis.

Background

Hydrogen has a high energy density and the only combustion product is water, and is therefore considered as an alternative to traditional fossil energy sources. The water electrolysis hydrogen production technology can utilize water as a raw material to prepare hydrogen, and is widely concerned. The electrolytic water reaction consists of Hydrogen Evolution Reaction (HER) of a cathode and Oxygen Evolution Reaction (OER) of an anode, and a catalyst with high catalytic activity is adopted as an electrode material, so that the reaction energy barrier can be reduced, and the energy loss can be reduced. Among non-noble metals, Ni is widely studied as a cathode catalyst because it has good HER activity. Numerous studies have shown that superior HER activity can be obtained by preparing binary or multi-Ni-based alloy catalysts compared to single-metal Ni materials. Therefore, a preparation method using Ni as one of the main components and introducing other metal elements has been a focus of research. The existing Ni-based material is limited by the defect of active sites, and the HER catalytic performance has room for improvement. A great deal of research is put into the preparation of Ni-based catalysts and the improvement of the micro-morphology, which increases the reaction area and the number of active sites, thereby enhancing the HER activity of the material.

Disclosure of Invention

The invention aims to overcome the defects of the prior Ni-based HER catalytic materialThe shortage of the material provides a preparation technology of the surface nano-porous NiMoCu catalyst. The invention adopts an electrochemical etching method, firstly utilizes Ni, Mo and Cu at 0.5M H₂SO₄And performing electrochemical etching on the NiMoCu master alloy strip to obtain the surface nano-porous NiMoCu material. The spongy nanoporous micro-morphology is obtained by etching, the active specific surface area is optimized, so that more active sites are exposed, and the water decomposition reaction is promoted. The catalyst prepared by the method can be used as an electrode material to efficiently catalyze the hydrogen production reaction by water electrolysis, and has potential application to other similar electrolysis and catalysis systems.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

(1)Ni₇₄Mo₆Cu₂₀preparation of master alloy strip

Preparing a master alloy by an electric arc melting technology by using high-purity metal Ni, metal Cu and metal Mo according to an atomic ratio of 74:20: 6. Then putting the master alloy into a quartz tube, and rapidly solidifying the master alloy cast ingot by using a single-roller rotary quenching system to prepare Ni₇₄Mo₆Cu₂₀Master alloy strip 1X 0.2cm²The thickness is 30 mu m;

(2) preparation of surface nano-porous NiMoCu

Ultrasonic cleaning Ni prepared by acetone and ultrapure water in sequence₇₄Mo₆Cu₂₀And the master alloy strip is dried and then is connected with an electrochemical workstation to be used as a working electrode in a three-electrode system. The gold flakes were treated in the same way at the same time and used as auxiliary electrodes; Ag/AgCl electrode as reference electrode at 0.5M H₂SO₄Performing electrochemical etching. The etching voltage is 1.25V (vs. Ag/AgCl), and the etching time is 300 s. After etching, cleaning the prepared NiMoCu with ultrapure water for 3 times, and naturally drying at room temperature;

drawings

FIG. 1 SEM image of nanoporous NiMoCu at 5000 magnification;

FIG. 2 SEM image of nanoporous NiMoCu at 200000 times;

FIG. 3 XRD diffraction patterns of the material before and after etching;

FIG. 4 EDS spectra of nanoporous NiMoCu;

FIG. 5 is a graph of HER performance of materials made at different etch times with an etch potential of 1.25V;

FIG. 6 is a Tafel plot corresponding to FIG. 5;

FIG. 7 is an EIS diagram of the material prepared under different etching times and an etching potential of 1.25V;

FIG. 8 is a comparison of nanoporous NiMoCu before and after 1000 cycles of cyclic voltammetry scan;

FIG. 9 i-t plot of nanoporous NiMoCu stability test at 100mV for 12 hours;

Detailed Description

The invention provides a preparation method of a surface nano-porous NiMoCu catalyst, and a specific implementation mode is as follows.

Preparing high-purity Ni, Cu and Mo ingots according to the atomic ratio of 74:20:6 into Ni by using an arc melting technology₇₄Mo₆Cu₂₀A master alloy. Rapidly solidifying master alloy cast ingot by using single-roller rotary quenching and spray casting system to prepare Ni₇₄Mo₆Cu₂₀Strip of master alloy and cutting the strip of master alloy into pieces of 1X 0.2cm²And (5) standby.

Respectively ultrasonically cleaning prepared Ni by using acetone and ultrapure water in sequence₇₄Mo₆Cu₂₀And (3) drying the master alloy strip for 20min, and connecting the dried master alloy strip with an electrochemical workstation to be used as a working electrode in a three-electrode system. The gold flakes were treated in the same way at the same time and used as auxiliary electrodes; Ag/AgCl electrode as reference electrode at 0.5M H₂SO₄Performing electrochemical etching. The etching voltage is 1.25V (vs. Ag/AgCl), and the etching time is 300 s. And after etching, cleaning the prepared surface nano-porous NiMoCu catalyst with ultrapure water, and naturally drying at room temperature.

In order to test the catalytic activity of the material, a NiMoCu catalyst with nano-porous surface is used as a working electrode, a gold sheet is used as an auxiliary electrode, an Ag/AgCl electrode is used as a reference electrode, and a Linear Sweep Voltammetry (LSV) test is carried out in 1M KOH. The test potential window is-0.9 to-1.4V (vs. Ag/AgCl), and the scanning speed is 5 mV.s^-1And converting the current to a current density. TestingThe results are shown in fig. 4 (experimental data IR compensated). The Tafel slope of the surface nano-porous NiMoCu is calculated to be 96mV dec^-1Current density of 10mA cm^-2The overpotential in this case was 90 mV.

In order to further test the electrochemical performance of the surface nano-porous NiMoCu catalyst, an alternating current impedance (EIS) test was performed. FIG. 7 is an EIS diagram of the material produced at an etching potential of 1.25V and at different etching times. It can be seen from the figure that the charge transfer resistance (R) of the corresponding material is gradually optimized along with the etching parameters_ct) There was also a consistent decrease in the size of the surface nanoporous NiMoCu catalyst prepared at 300s with the lowest charge transfer resistance, indicating the highest phase interface exchange efficiency and electron conductivity, which also explains its excellent HER performance.

In order to test the stability of the material under long-time work, cyclic voltammetry scanning and chronoamperometric test are carried out on the surface nano-porous NiMoCu catalyst, the cyclic voltammetry scanning potential interval is-0.2-0.3V vs. RHE, and the scanning rate is 0.1 V.s^-1. As can be seen from fig. 8, the current density of the surface nanoporous NiMoCu catalyst at the 1000 th turn is not significantly reduced compared to the first turn. In addition, the NiMoCu catalyst with the nano-porous surface is placed under 100mV to work for 12 hours, and still keeps larger current density, which shows that the NiMoCu catalyst has better stability.

Claims

1. A preparation method of a surface nano-porous NiMoCu catalyst is characterized by comprising the following steps:

(1)Ni₇₄Mo₆Cu₂₀preparation of master alloy strip

Preparing high-purity metals Ni, Cu and Mo into Ni according to the atomic ratio of 74:20:6 by an electric arc melting technology₇₄Mo₆Cu₂₀A master alloy strip having a thickness of 30 μm;

(2) preparation of NiMoCu catalyst with porous surface

Ultrasonic cleaning Ni prepared by acetone and ultrapure water in sequence₇₄Mo₆Cu₂₀And the master alloy strip is dried and then connected with an electrochemical workstation to be used as a working electrode in a three-electrode system. At the same time useThe gold piece was treated in the same manner and used as an auxiliary electrode; Ag/AgCl electrode as reference electrode at 0.5M H₂SO₄Performing electrochemical etching. The etching voltage is 1.25V, and the etching time is 300 s. And after etching, cleaning the prepared NiMoCu catalyst with porous surface by using ultrapure water, and naturally drying at room temperature.

2. A surface-porous NiMoCu catalyst prepared according to the process of claim 1.