Preparation method and application of copper-gallium alloy electrocatalyst

Abstract

The invention is applicable to the related field of material preparation, and provides a preparation method and application of a copper-gallium alloy electrocatalyst, and the preparation method of the copper-gallium alloy electrocatalyst comprises the following steps: step 1, immersing a pretreated carbon nanotube in an N, N-dimethylformamide solution of copper chloride; 2, the gallium-indium liquid alloy is subjected to ultrasonic dispersion in an N, N-dimethylformamide solution; and 3, mixing the solutions obtained in the step 1 and the step 2, continuously performing ultrasonic treatment, and centrifuging, washing and drying the obtained product to obtain a finished product. According to the preparation method, copper ions and a gallium-indium liquid alloy are taken as raw materials, and a nanoscale copper-gallium alloy intermetallic compound is prepared by a couple replacement method and is anchored on a carbon nanotube in situ; due to the synergistic effect between atoms, the copper-gallium alloy can effectively activate nitric oxide on the surface, and the adsorption energy and the speed-step energy barrier of the copper-gallium alloy to the nitric oxide are reduced, so that the copper-gallium alloy is endowed with excellent NORR catalytic activity.

Description

Technical Field

[0001] The present invention relates to the related field of material preparation, and in particular to a method for preparing a copper-gallium alloy electrocatalyst and application thereof. Background Art

[0002] Ammonia plays an irreplaceable and important role in agriculture, industry and pharmaceuticals. At present, the industry relies on the Haber-Bush process to produce ammonia. However, this method consumes a lot of energy and brings serious environmental pollution. The electrochemical reduction of nitric oxide to synthesize ammonia (NORR) driven by renewable energy can reduce the consumption of fossil fuels and remove nitric oxide pollutants in the air. It is a promising alternative to synthesizing ammonia. Studies have shown that copper-based catalysts based on metallic copper have certain application potential in the field of NORR. However, the performance of copper-based catalysts at low nitric oxide concentrations (<5%) similar to air pollutants is poor and cannot meet actual needs. In addition, the size of the copper-gallium alloy catalysts reported so far is relatively large, generally in the micron or even millimeter range. This type of catalyst has a small specific surface area and is not suitable for use as a catalyst. A few reports on nano-scale copper-gallium alloys generally use metal organic compounds as precursors and are synthesized at higher temperatures. The raw materials are rare and expensive, the preparation process is complicated, and the equipment requirements are high.

[0003] Therefore, in view of the above situation, there is an urgent need to provide a NORR electrocatalyst for low nitric oxide concentration to overcome the shortcomings in current practical applications. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a copper-gallium alloy electrocatalyst and its application in NORR at low nitrogen monoxide concentration, aiming to solve the problems in the above-mentioned background technology.

[0005] The present invention provides a novel method for preparing a copper-gallium alloy electrocatalyst, which comprises the following steps:

[0006] Step 1: Immerse the pretreated carbon nanotubes in a cupric chloride N,N-dimethylformamide solution and let stand for a period of time;

[0007] Step 2: Ultrasonic dispersion of gallium-indium liquid alloy in N,N-dimethylformamide solution;

[0008] Step 3: Mix the solutions obtained in step 1 and step 2 and continue to sonicate, then centrifuge, wash and dry the obtained product to obtain the finished product.

[0009] The copper-gallium alloy electrocatalyst is a supported electrocatalyst, which is composed of copper-gallium alloy nanoparticles supported on carbon nanotubes. The chemical composition of the copper-gallium alloy is CuGa2, which is an intermetallic compound. The particle size of the copper-gallium alloy nanoparticles is 3 to 5 nanometers.

[0010] As a further solution of the present invention: in step 1, the mass of the carbon nanotubes is 0.1 g, the mass of the copper chloride is 0.1-1 g, the volume of the N,N-dimethylformamide solution is 20 ml, and the standing time is 8-32 h.

[0011] As a further solution of the present invention: in step 2, the volume of the gallium-indium liquid alloy is 25-100 μl, the volume of the N,N-dimethylformamide solution is 15 ml, the ultrasonic time is 0.5-2 h, and the ultrasonic power is 600-900 w.

[0012] As a further solution of the present invention: in step 3, the ultrasonic time is 15-60 min, the drying temperature is 60° C., and the drying time is 8 h.

[0013] The present invention also provides an application of the copper-gallium alloy electrocatalyst in the electrochemical synthesis of ammonia from nitric oxide: an appropriate amount of copper-gallium alloy electrocatalyst powder is weighed and dispersed in a mixed solution of ethanol and naphthol, an appropriate amount of the suspension is dripped on the surface of carbon paper, and after the carbon paper is dried, it is used as a working electrode for electrocatalytic reaction.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] In terms of catalyst composition and structure, the present invention uses copper ions and gallium-indium liquid alloy as raw materials, prepares nano-scale copper-gallium alloy intermetallic compounds by galvanic displacement method, and anchors them in situ on carbon nanotubes. The particle size of the copper-gallium alloy nanoparticles is 3-5nm. In terms of preparation method, the preparation can be carried out at room temperature, the raw materials are simple and easy to obtain, the cost is low, the reaction device is simple, and the process is short. In terms of catalytic application, when the catalyst is used for low-concentration nitric oxide electrocatalytic reduction, very excellent catalytic performance can be obtained. In NO with a concentration of 2%, in a 0.5 mol / L sodium sulfate solution, the ammonia yield is 162 μg h - 1 mg -1 , with a Faraday efficiency of 99%; its high selectivity and ammonia yield are attributed to the strong intrinsic catalytic activity of the copper-gallium alloy; due to the synergistic effect between atoms, the copper-gallium alloy can effectively activate nitric oxide on the surface and reduce its adsorption energy for nitric oxide and the rate-determining step energy barrier, thus giving the copper-gallium alloy excellent NORR catalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the XRD pattern of the copper-gallium alloy electrocatalyst.

[0017] Figure 2 Transmission electron microscope image of copper-gallium alloy electrocatalyst.

[0018] Figure 3 Linear sweep voltammetry curves of an electrode prepared for copper-gallium alloy in 0.5 mol / L sodium sulfate solution in argon atmosphere and nitric oxide (2%) atmosphere.

[0019] Figure 4 Chronoamperometric curve of an electrode prepared from copper-gallium alloy in a 0.5 mol / L sodium sulfate solution and a nitric oxide (2%) atmosphere. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The specific implementation of the present invention is described in detail below in combination with specific embodiments.

[0021] See also Figure 1-Figure 4 , an embodiment of the present invention provides a method for preparing a copper-gallium alloy electrocatalyst, the method comprising the following steps:

[0022] Step 1: Immerse the pretreated carbon nanotubes in a cupric chloride N,N-dimethylformamide solution and let it stand for a period of time; wherein the mass of the carbon nanotubes is 0.1g, the mass of the cupric chloride is 0.1-1g, the volume of the N,N-dimethylformamide solution is 20ml, and the standing time is 8-32h.

[0023] Step 2: Ultrasonic dispersion of gallium-indium liquid alloy in N,N-dimethylformamide solution; wherein the volume of gallium-indium liquid alloy is 25-100 μl, the volume of N,N-dimethylformamide solution is 15 ml, the ultrasonic time is 0.5-2 h, and the ultrasonic power is 600-900 w.

[0024] Step 3: Mix the solutions obtained in step 1 and step 2 and continue to sonicate, then centrifuge, wash and dry the obtained product to obtain the finished product; the sonication time is 15-60 min, the drying temperature is 60° C., and the drying time is 8 h.

[0025] In terms of catalyst composition and structure, the present invention uses copper ions and gallium-indium liquid alloy as raw materials, prepares nano-scale copper-gallium alloy intermetallic compounds by galvanic displacement method, and anchors them in situ on carbon nanotubes. The particle size of the copper-gallium alloy nanoparticles is 3-5nm. In terms of preparation method, the preparation can be carried out at room temperature, the raw materials are simple and easy to obtain, the cost is low, the reaction device is simple, and the process is short. In terms of catalytic application, when the catalyst is used for low-concentration nitric oxide electrocatalytic reduction, very excellent catalytic performance can be obtained. In NO with a concentration of 2%, in a 0.5 mol / L sodium sulfate solution, the ammonia yield is 162 μg h - 1 mg -1 , with a Faraday efficiency of 99%; its high selectivity and ammonia yield are attributed to the strong intrinsic catalytic activity of the copper-gallium alloy; due to the synergistic effect between atoms, the copper-gallium alloy can effectively activate nitric oxide on the surface and reduce its adsorption energy for nitric oxide and the rate-determining step energy barrier, thus giving the copper-gallium alloy excellent NORR catalytic activity.

[0026] Embodiment 1

[0027] Step 1: Immerse the pretreated carbon nanotubes in a copper chloride N,N-dimethylformamide solution and let it stand for a period of time; wherein the mass of the carbon nanotubes is 0.1 g, the mass of the copper chloride is 0.2 g, the volume of the N,N-dimethylformamide solution is 20 ml, and the standing time is 8 hours.

[0028] Step 2: Ultrasonic dispersion of gallium-indium liquid alloy in N,N-dimethylformamide solution; wherein the volume of gallium-indium liquid alloy is 25 μl, the volume of N,N-dimethylformamide solution is 15 ml, the ultrasonic time is 0.5 h, and the ultrasonic power is 600 w.

[0029] Step 3: After mixing the solutions obtained in step 1 and step 2, continue to sonicate, then centrifuge, wash, and dry the obtained product to obtain the finished product; the sonication time is 15 min, the drying temperature is 60° C., and the drying time is 8 h.

[0030] Embodiment 2

[0031] Step 1: Immerse the pretreated carbon nanotubes in a copper chloride N,N-dimethylformamide solution and let it stand for a period of time; wherein the mass of the carbon nanotubes is 0.1 g, the mass of the copper chloride is 0.4 g, the volume of the N,N-dimethylformamide solution is 20 ml, and the standing time is 16 hours.

[0032] Step 2: Ultrasonic dispersion of gallium-indium liquid alloy in N,N-dimethylformamide solution; wherein the volume of gallium-indium liquid alloy is 50 μl, the volume of N,N-dimethylformamide solution is 15 ml, the ultrasonic time is 1 h, and the ultrasonic power is 700 w.

[0033] Step 3: After mixing the solutions obtained in step 1 and step 2, continue to sonicate, then centrifuge, wash and dry the obtained product to obtain the finished product; the sonication time is 30 minutes, the drying temperature is 60° C., and the drying time is 8 hours.

[0034] Embodiment 3

[0035] Step 1: Immerse the pretreated carbon nanotubes in a copper chloride N,N-dimethylformamide solution and let it stand for a period of time; wherein the mass of the carbon nanotubes is 0.1 g, the mass of the copper chloride is 0.6 g, the volume of the N,N-dimethylformamide solution is 20 ml, and the standing time is 24 hours.

[0036] Step 2: Ultrasonic dispersion of gallium-indium liquid alloy in N,N-dimethylformamide solution; wherein the volume of gallium-indium liquid alloy is 75 μl, the volume of N,N-dimethylformamide solution is 15 ml, the ultrasonic time is 1.5 h, and the ultrasonic power is 800 w.

[0037] Step 3: After mixing the solutions obtained in step 1 and step 2, continue to sonicate, then centrifuge, wash, and dry the obtained product to obtain the finished product; the sonication time is 45 minutes, the drying temperature is 60° C., and the drying time is 8 hours.

[0038] Embodiment 4

[0039] Step 1: Immerse the pretreated carbon nanotubes in a cupric chloride N,N-dimethylformamide solution and let it stand for a period of time; wherein the mass of the carbon nanotubes is 0.1 g, the mass of the cupric chloride is 0.8 g, the volume of the N,N-dimethylformamide solution is 20 ml, and the standing time is 32 h.

[0040] Step 2: Ultrasonic dispersion of gallium-indium liquid alloy in N,N-dimethylformamide solution; wherein the volume of gallium-indium liquid alloy is 100 μl, the volume of N,N-dimethylformamide solution is 15 ml, the ultrasonic time is 2 h, and the ultrasonic power is 900 w.

[0041] Step 3: After mixing the solutions obtained in step 1 and step 2, continue to sonicate, then centrifuge, wash and dry the obtained product to obtain the finished product; the sonication time is 60 min, the drying temperature is 60° C., and the drying time is 8 h.

[0042] The present invention also provides an application of the copper-gallium alloy electrocatalyst in the electrochemical synthesis of ammonia from nitric oxide: an appropriate amount of copper-gallium alloy electrocatalyst powder is weighed and dispersed in a mixed solution of ethanol and naphthol, an appropriate amount of the suspension is dripped on the surface of carbon paper, and after the carbon paper is dried, it is used as a working electrode for electrocatalytic reaction.

[0043] In summary, the working principle of the present invention is to utilize the different standard reduction potentials of copper and gallium, and use gallium to reduce copper ions through the galvanic displacement method, and the excess gallium will continue to wet with the single copper to form a copper-gallium alloy, thereby obtaining a sample. The method for preparing the sample is different from the previous method for preparing gallium-based intermetallic compounds. The copper ions are fixed on carbon nanotubes to disperse them, thereby anchoring the copper-gallium alloy, thereby effectively reducing the size of the copper-gallium alloy.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a copper-gallium alloy electrocatalyst, characterized in that: The method comprises the following steps: Step 1: Immerse the pretreated carbon nanotubes in a cupric chloride N,N-dimethylformamide solution and let stand for a period of time; Step 2: Ultrasonic dispersion of gallium-indium liquid alloy in N,N-dimethylformamide solution; Step 3: Mix the solutions obtained in step 1 and step 2 and continue to sonicate, then centrifuge, wash and dry the obtained product to obtain the finished product.

2. The method for preparing a copper-gallium alloy electrocatalyst according to claim 1, characterized in that: In step 1, the mass of carbon nanotubes is 0.1 g, the mass of copper chloride is 0.1-1 g, the volume of N,N-dimethylformamide solution is 20 ml, and the standing time is 8-32 h.

3. The method for preparing a copper-gallium alloy electrocatalyst according to claim 1, characterized in that: In step 2, the volume of the gallium-indium liquid alloy is 25-100 μl, the volume of the N,N-dimethylformamide solution is 15 ml, the ultrasonic time is 0.5-2 h, and the ultrasonic power is 600-900 w.

4. The method for preparing a copper-gallium alloy electrocatalyst according to claim 1, characterized in that: In step 3, the ultrasonic time is 15-60 min, the drying temperature is 60° C., and the drying time is 8 h.

5. Use of the copper-gallium alloy electrocatalyst prepared by the method for preparing the copper-gallium alloy electrocatalyst according to any one of claims 1 to 4 in the electrocatalytic reaction of synthesizing ammonia from nitric oxide, wherein the Faraday efficiency reaches 99% when the concentration of nitric oxide is lower than 2%.

Images