阅读说明：本技术 一种钼硒双元素掺杂的多孔片层状磷化镍材料的制备方法及应用 (Preparation method and application of molybdenum-selenium double-element doped porous sheet layered nickel phosphide material ) 是由 崔小强 刘弘太 徐珊 许天翊 于 2021-11-18 设计创作，主要内容包括：本发明公开了一种钼硒双掺杂的多孔片层状磷化镍电催化剂的制备方法与应用,获得了较为优秀的催化性能。本发明实现了通过物理吸附和氮气氛围下的硒化和磷化,合成了一种多孔状的片层结构的催化剂,其具备高的导电性和高的比表面积,掺杂多种元素调控了镍的电子结构和价态,使其电催化析氢性能有了明显的提升。在碱性电解液中,电流密度10 mA/cm～(2)过电位仅43mV。其多孔状结构利于氢气的脱附,并且多孔结构暴露的更多的比表面积给催化反应提供了更多的活性位点,其泡沫镍作为支撑催化剂的骨架增强了其导电性和稳定性,使催化剂具有良好的稳定性。(The invention discloses a preparation method and application of a molybdenum-selenium double-doped porous sheet layered nickel phosphide electrocatalyst, and relatively excellent catalytic performance is obtained. The invention realizes the synthesis of the porous catalyst with the lamellar structure through physical adsorption and selenization and phosphorization under the nitrogen atmosphere, has high conductivity and high specific surface area, and is doped with various elements to regulate and control the electronic structure and valence state of nickel, so that the electro-catalytic hydrogen evolution performance of the catalyst is obviously improved. In an alkaline electrolyte, the current density is 10 mA/cm 2 The overpotential is only 43 mV. The porous structure is beneficial to desorption of hydrogen, and the more specific surface area exposed by the porous structure provides more for catalytic reactionThe nickel foam of the catalyst is used as a framework for supporting the catalyst, so that the conductivity and the stability of the catalyst are enhanced, and the catalyst has good stability.)

1. A preparation method of a molybdenum-selenium double-doped porous sheet layered nickel phosphide electrocatalyst is characterized by comprising the following steps of:

(1) immersing the foamed nickel in a mixed solution consisting of 0.6g of urea, 0.148g of ammonium fluoride, 0.29g of nickel nitrate hexahydrate and 50ml of deionized water, carrying out hydrothermal reaction for 10 hours at 120 ℃ in a hydrothermal reaction kettle to obtain foamed nickel with nickel hydroxide nanosheets, washing with water and ethanol, and drying;

(2) immersing the product obtained in the step 1 in 20ml of ethanol containing 0.5g of molybdenum chloride, taking out after soaking for 30min, and drying in the air environment at room temperature;

(3) and (3) placing the foamed nickel dried in the step (2) into a tubular furnace, wherein 0.5g of selenium powder and 3g of NaH2PO 2. H2O are independently placed at the upstream of the tubular furnace, and sintering the tubular furnace at the high temperature of 300 ℃ for 2H under nitrogen saturation to finally obtain the molybdenum-selenium co-doped nickel phosphide electrocatalyst.

2. The molybdenum selenium double-doped porous sheet layered nickel phosphide electrocatalyst prepared by the method of claim 1, and the application thereof in hydrogen evolution reaction.

3. The application of claim 2, wherein a conventional three-electrode system is adopted, the electrolyte is 1.0M KOH solution, the carbon rod is used as a counter electrode, the silver-silver chloride electrode is used as a reference electrode, and the molybdenum-selenium double-doped porous sheet layered nickel phosphide electrocatalyst is used as a working electrode to perform hydrogen evolution reaction.

Technical Field

The invention belongs to the technical field of catalysts, and particularly relates to a preparation method and application of a molybdenum-selenium double-doped nickel phosphide electrocatalyst.

Background

In the face of the environmental problems caused by the combustion of fossil fuels and the problem of exhaustion of fossil fuels, it is urgent to find a clean and renewable energy source to replace the traditional fossil energy source. At present, new energy sources such as wind energy and light energy are widely used in partial areas, while hydrogen energy is widely concerned by researchers due to the fact that the hydrogen energy has high energy density and the fact that combustion products of the hydrogen energy are only water-friendly, and electrocatalytic water decomposition involves two catalytic reactions, namely, an anodic Oxygen Evolution Reaction (OER) and a cathodic Hydrogen Evolution Reaction (HER), wherein the oxygen evolution reaction generates oxygen at one stage and the hydrogen evolution reaction generates hydrogen at one stage. At present, a hydrogen evolution catalyst widely used commercially is Pt/C, but because Pt is used as a noble metal, the higher price and the lower storage capacity on the earth prevent further commercial application of Pt/C, the search for a catalyst material capable of replacing Pt becomes important and difficult for solving the research of hydrogen production reaction by electrocatalytic water decomposition.

At present, researchers have sought non-metallic catalysts to replace commercial Pt/C for water splitting catalytic reactions. Usually, the electronic regulation of the chemical valence state of the catalyst is carried out by changing the composition structure of the catalyst, and the electronic structure of the catalyst can be coordinated to improve the intrinsic activity of the catalyst by constructing a heterojunction or introducing element doping. Or the morphology of the catalyst is changed, more catalytic active sites are exposed, and the catalytic activity of the catalyst is improved. According to the method for accurately synthesizing the molybdenum-selenium co-doped nickel phosphide material, the specific surface area of the doped nickel phosphide is remarkably increased, more active sites are exposed, the activity of the hydrogen production reaction by electrolyzing water is greatly improved, the stability is long, and the application of transition metal phosphide series materials in industrial catalysis is promoted.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a preparation method and application of a molybdenum-selenium-codoped porous sheet layered structure nickel phosphide material. The electrocatalyst has a porous sheet layered structure, has high specific surface area and excellent performances such as good conductivity and the like, and can be used for electrocatalytic hydrogen evolution reaction.

The purpose of the invention is realized by the following technical scheme: firstly, synthesizing a nickel hydroxide nanosheet array as a precursor, then soaking the nickel hydroxide nanosheet array in an ethanol solution containing molybdenum chloride, taking out the nickel hydroxide nanosheet array after half an hour, and naturally drying the nickel hydroxide nanosheet array in an air atmosphere at room temperature. Then, the nickel is placed into a tubular furnace, selenium powder and sodium hypophosphite monohydrate are placed at the upstream, phosphorization and selenization are carried out at 300 ℃, and finally the synthesized molybdenum-selenium co-doped nickel phosphide has good conductivity and high specific surface area, exposes more catalytic active sites, and has good electrocatalytic hydrogen evolution activity and good stability.

Specifically, the scheme comprises the following steps:

(1) immersing the foamed nickel in a mixed solution consisting of 0.6g of urea, 0.148g of ammonium fluoride, 0.29g of nickel nitrate hexahydrate and 50ml of deionized water, carrying out hydrothermal reaction for 10 hours at 120 ℃ in a hydrothermal reaction kettle to obtain the foamed nickel with the nickel hydroxide nanosheets, washing with water and ethanol, and drying.

(2) And (3) immersing the product obtained in the step (1) in 20ml of ethanol containing 0.5g of molybdenum chloride, taking out after 30min of soaking, and drying at room temperature in the air environment.

(3) And (3) placing the foamed nickel dried in the step (2) into a tubular furnace, wherein 0.5g of selenium powder and 3g of NaH2PO 2. H2O are independently placed at the upstream of the tubular furnace, and sintering the tubular furnace at the high temperature of 300 ℃ for 2H under nitrogen saturation to finally obtain the molybdenum-selenium co-doped nickel phosphide electrocatalyst.

The invention also provides application of the molybdenum-selenium co-doped porous sheet layered structure nickel phosphide electrocatalyst in the field of hydrogen evolution reaction.

Specifically, the HER catalytic performance of the catalyst was evaluated in a conventional three-electrode system. The electrolyte is 1.0M KOH solution, the carbon rod is a counter electrode, the silver-silver chloride electrode is a reference electrode, and the molybdenum-selenium co-doped porous sheet layered structure nickel phosphide electrocatalyst is a working electrode, so that hydrogen evolution reaction is carried out.

The invention has the beneficial effects that: the invention realizes the synthesis of a porous catalyst with a lamellar structure through physical adsorption and selenization and phosphorization under the nitrogen atmosphere, has high conductivity and high specific surface area, is doped with various elements to regulate and control the electronic structure and valence state of nickel, and ensures that the nickel is subjected to electrocatalysisThe hydrogen evolution performance is obviously improved. In an alkaline electrolyte, the current density is 10 mA/cm²The overpotential is only 43 mV. The porous structure is beneficial to desorption of hydrogen, more specific surface areas exposed by the porous structure provide more active sites for catalytic reaction, and the foamed nickel serving as a framework for supporting the catalyst enhances the conductivity and stability of the catalyst, so that the catalyst has good stability.

Drawings

FIG. 1 is an X-ray diffraction pattern (XRD) of sample one (Ni 2P) and sample two (MoSe-Ni2P) prepared in example 1.

FIG. 2 is a Scanning Electron Micrograph (SEM) of sample one (Ni 2P) and sample two (MoSe-Ni2P) made in example 1.

FIG. 3 is the electrochemical polarization curves of sample one (Ni 2P) and sample two (MoSe-Ni2P) as hydrogen evolution catalysts, respectively, in example 2.

Detailed Description

The technical solution of the invention is further illustrated below with reference to examples, which are not to be construed as limiting the technical solution.

Example 1:

sample one: preparation of Ni2P

(1) And (3) sequentially performing ultrasonic cleaning on the foamed nickel (abbreviated as NF) for 15min by using acetone, water, hydrochloric acid and ethanol to remove oil stains and oxide layers on the surface, and drying for later use.

(2) Dissolving 0.6g of urea, 0.148g of ammonium fluoride, 0.29g of nickel nitrate hexahydrate and 15 square centimeters of foamed nickel in 50ml of deionized water, uniformly stirring, then placing into a 100ml reaction kettle, and burning at 120 ℃ for 10 hours.

(3) And (3) taking out the foamed nickel growing with the nickel hydroxide nanosheets in the reaction kettle in the step (2), washing the foamed nickel with water and ethanol, and drying.

(4) And (4) putting the foamed nickel dried in the step (3) into a tubular furnace, placing NaH2PO2 & H2O 3g at the upstream, sintering at the temperature of 300 ℃ under nitrogen saturation, and preserving heat for 2 hours to finally obtain the nickel phosphide electrocatalyst.

Sample two: molybdenum-selenium co-doped porous sheet layered structure nickel phosphide electrocatalyst (MoSe-Ni2P)

(1) And (3) sequentially performing ultrasonic cleaning on the foamed nickel (abbreviated as NF) for 15min by using acetone, water, hydrochloric acid and ethanol to remove oil stains and oxide layers on the surface, and drying for later use.

(2) Dissolving 0.6g of urea, 0.148g of ammonium fluoride, 0.29g of nickel nitrate hexahydrate and 15 square centimeters of foamed nickel in 50ml of deionized water, uniformly stirring, then placing into a 100ml reaction kettle, and burning at 120 ℃ for 10 hours.

(3) And (3) taking out the foamed nickel growing with the nickel hydroxide nanosheets in the reaction kettle in the step (2), washing the foamed nickel with water and ethanol, and drying.

(4) And soaking the dried foam nickel with the nickel hydroxide nanosheets into 20ml of ethanol containing 0.5g of molybdenum chloride for 30min, taking out, and drying at room temperature in the air environment.

(5) And (3) putting the foamed nickel dried in the step (4) into a tubular furnace, placing 0.5g of selenium powder and 0.5g of NaH2PO2 & H2O 3g of selenium powder at the upstream, sintering at the temperature of 300 ℃ under nitrogen saturation, and preserving heat for 2 hours to finally obtain the molybdenum-selenium co-doped nickel phosphide electrocatalyst.

Fig. 1 is an X-ray diffraction pattern of a first sample (Ni 2P) and a second sample (molybdenum selenium co-doped porous sheet layered structured nickel phosphide electrocatalyst MoSe-Ni2P) prepared in this example, and it can be seen from the X-ray diffraction patterns that the first sample has a characteristic peak of nickel phosphide, and the first sample is still a characteristic peak of nickel phosphide after being double-doped with molybdenum selenium, and has no change in other peak positions.

Fig. 2 is a Scanning Electron Microscope (SEM) image of a first sample (Ni 2P) and a second sample (molybdenum selenium co-doped porous sheet layered structure nickel phosphide electrocatalyst MoSe-Ni2P) prepared in this example, Ni2P in the first sample is in a bulk structure, and the second sample can obviously observe the porous sheet layered structure, and can see that it exposes more surface area and more active sites from scanning, thereby improving the activity of the electrocatalytic reaction.

Example 2:

sample one (Ni 2P) and sample two (molybdenum selenium co-doped porous sheet layered structure nickel phosphide electrocatalyst MoSe-Ni2P) prepared in example 1 were further evaluated for HER catalytic performance of the catalysts in a three-electrode system. In the electrolyte of 1.0M KOH solution, a sample I (Ni 2P) with the size of 1.5cm multiplied by 1cm is taken as a working electrode, a carbon rod is taken as a counter electrode, and a silver-silver chloride electrode is taken as a reference electrode, and hydrogen evolution reaction is carried out. Then, in a KOH solution with the electrolyte of 1.0M, a sample II (molybdenum-selenium co-doped porous sheet layered structure nickel phosphide electrocatalyst MoSe-Ni2P) with the size of 1.5cm multiplied by 1cm is used as a working electrode, a carbon rod is used as a counter electrode, and a silver-silver chloride electrode is used as a reference electrode, so that hydrogen evolution reaction is carried out.

Fig. 3 is an electrochemical polarization curve of sample one (Ni 2P) and sample two (molybdenum selenium co-doped porous sheet layered structure nickel phosphide electrocatalyst MoSe-Ni2P) as hydrogen evolution reaction catalysts in example 2, respectively. Sample I (Ni 2P) is used as a hydrogen evolution reaction catalyst, and the system reaches 10 mA/cm when the sweep rate is measured at the sweep rate of 5mV/S²The overpotential at the current density of (1) is 100 mV. A sample II (molybdenum-selenium co-doped porous sheet layered structure nickel phosphide electrocatalyst MoSe-Ni2P) is used as a hydrogen evolution reaction catalyst, and the system reaches 10 mA/cm when the scanning speed is measured at the scanning speed of 5mV/S²At a current density of (2), the overpotential is only 43 mV.

The invention realizes the synthesis of the porous catalyst with the lamellar structure through physical adsorption and selenization and phosphorization under the nitrogen atmosphere, has high conductivity and high specific surface area, and is doped with various elements to regulate and control the electronic structure and valence state of nickel, so that the electro-catalytic hydrogen evolution performance of the catalyst is obviously improved. In an alkaline electrolyte, the current density is 10 mA/cm²The overpotential is only 43 mV. The porous structure is beneficial to desorption of hydrogen, more specific surface areas exposed by the porous structure provide more active sites for catalytic reaction, and the foamed nickel serving as a framework for supporting the catalyst enhances the conductivity and stability of the catalyst, so that the catalyst has good stability. The electrocatalyst shows excellent catalytic activity in alkaline hydrogen evolution reaction, and promotes the further application of transition metal phosphide in the field of water decomposition.