阅读说明：本技术 一种山丘状原位镍钒双金属氢氧化物催化剂及其制备方法和应用 (Hillock-shaped in-situ nickel-vanadium double metal hydroxide catalyst and preparation method and application thereof ) 是由 曹丽云 何丹阳 冯亮亮 黄剑锋 吴建鹏 赵亚娟 杨丹 于 2019-11-05 设计创作，主要内容包括：本发明公开一种山丘状原位镍钒双金属氢氧化物催化剂及其制备方法和应用,步骤一：泡沫镍预处理；步骤二：取氯化钒和尿素同时加入到醇和氮甲基吡咯烷酮的混合溶剂；步骤三：将泡沫镍浸泡在溶液A中于115～125℃下进行23～25h的溶剂热反应；步骤四：反应结束后,将反应釜自然冷却至室温后,经过水醇交替清洗后并收集烘干,得到山丘状原位镍钒双金属氢氧化物催化剂；本发明采用溶剂热法具有制备过程简单、低的合成温度、不需要大型的设备和苛刻的条件等特点,制备的山丘状原位镍钒双金属氢氧化物催化剂的高活性和高稳定性,在碱性和中性条件下具有良好的全解水性能。(The invention discloses a hill-shaped in-situ nickel-vanadium double metal hydroxide catalyst and a preparation method and application thereof, and the method comprises the following steps: pretreating foamed nickel; step two: adding vanadium chloride and urea into a mixed solvent of alcohol and N-methyl pyrrolidone; step three: soaking the foamed nickel in the solution A to perform a solvothermal reaction at 115-125 ℃ for 23-25 h; step four: after the reaction is finished, naturally cooling the reaction kettle to room temperature, alternately cleaning the reaction kettle by water and alcohol, collecting and drying the reaction kettle to obtain a hill-shaped in-situ nickel-vanadium double metal hydroxide catalyst; the method has the characteristics of simple preparation process, low synthesis temperature, no need of large-scale equipment and harsh conditions and the like by adopting a solvothermal method, and the prepared hill-shaped in-situ nickel-vanadium double metal hydroxide catalyst has high activity and high stability and has good full-hydrolytic performance under alkaline and neutral conditions.)

1. A preparation method of a hill-shaped in-situ nickel-vanadium double metal hydroxide catalyst is characterized by comprising the following steps:

the method comprises the following steps: pretreating foamed nickel;

step two: adding 62.92-70.78 mg of vanadium chloride and 66-78 mg of urea into a mixed solvent of alcohol and N-methylpyrrolidone, and uniformly stirring to obtain a solution A;

step three: soaking the foamed nickel treated in the step one in the solution A, pouring the foamed nickel into an inner reaction kettle, fixing the inner kettle in an outer kettle, placing the inner kettle in a homogeneous phase reactor, and carrying out solvothermal reaction at the rotating speed of 5-8 r/min and at the temperature of 115-125 ℃ for 23-25 h;

step four: after the reaction is finished, naturally cooling the reaction kettle to room temperature, then taking out the product foamed nickel after the reaction, and collecting the product foamed nickel after the product foamed nickel is alternately cleaned by water and alcohol;

step five: and drying the foamed nickel collected in the fourth step to obtain the hill-shaped in-situ nickel-vanadium double metal hydroxide catalyst.

2. The method of preparing a hill-shaped in situ nickel vanadium double hydroxide catalyst as claimed in claim 1, wherein: the step one, foam nickel pretreatment, namely, performing ultrasonic cleaning on cut 1cm multiplied by 4.5cm foam nickel in an acetone solution for 12-15 min, then pouring the foam nickel into prepared 1-3 mol/L hydrochloric acid for ultrasonic cleaning for 5-8 min, finally alternately washing the foam nickel for 3-4 times by using absolute ethyl alcohol and ultrapure water respectively, and then performing vacuum drying for 10-15 h at the temperature of 28-33 ℃.

3. The method of preparing a hill-shaped in situ nickel vanadium double hydroxide catalyst as claimed in claim 1, wherein: and the volume ratio of the azomethidone to the alcohol in the mixed solvent in the second step is 1 (9-11).

4. The method of preparing a hill-shaped in situ nickel vanadium double hydroxide catalyst as claimed in claim 1, wherein: and in the second step, magnetic stirring is adopted in the stirring process, and the stirring time is 15-20 min.

5. The method of preparing a hill-shaped in situ nickel vanadium double hydroxide catalyst as claimed in claim 1, wherein: and the solution A in the third step reacts in the reaction inner kettle, and the filling ratio is 60-64%.

6. The method of preparing a hill-shaped in situ nickel vanadium double hydroxide catalyst as claimed in claim 1, wherein: and in the fourth step, washing is carried out for 3-4 times by alternately washing with ultrapure water and absolute ethyl alcohol.

7. The method of preparing a hill-shaped in situ nickel vanadium double hydroxide catalyst as claimed in claim 1, wherein: and the drying temperature in the fifth step is 70-75 ℃, and the drying time is 4-6 h.

8. A hill-shaped in situ nickel vanadium double hydroxide catalyst prepared according to the method of claims 1-7.

9. Use of the hill-shaped in situ nickel vanadium double hydroxide catalyst of claim 8 in hydrogen and oxygen evolution reactions under basic and neutral conditions.

Technical Field

The invention belongs to the field of electrocatalytic materials, and particularly relates to a hillock-shaped in-situ nickel-vanadium double metal hydroxide catalyst, and a preparation method and application thereof.

Background

With the increasing environmental pollution and the rapid consumption of fossil fuels, the development of renewable sustainable energy sources is imperative. Electrolysis of water to produce hydrogen (H) due to its carbon-free emission₂) And oxygen (O)₂) Is considered to be one of the most promising and competitive solutions^[1]In the field of electrocatalysis, noble metal-based materials (oxides of Pt, Ru or Ir) are currently the best hydrogen-generating electrocatalysts, and their practical application is severely limited by scarcity and high cost.

Therefore, in recent years, researchers have been dedicated to the development of non-noble metal hydrogen production electrocatalysts with high catalytic activity, which are composed of elements with high abundance of crusta. Ni-based Layered Double Hydroxides (LDH) have long been recognized as promising anode catalysts whose performance can be enhanced by doping with heteroatoms^[2](transition metals V, Fe, Co, Mn, etc.; non-metals N, S, P, Se, etc.) and compounding with conductive substrates^[3]Further improvements have been made in methods such as carbon nanotubes, nickel foam, graphene, carbon fiber paper, and the like. Therefore, Ni-based LDHs show great potential as Oxygen Evolution Reaction (OER) anode catalysts and Hydrogen Evolution Reaction (HER) cathode catalysts and ultimately are able to drive bulk water splitting reactions at low operating potentials. Luan^[4]Et al report on two-dimensional alpha-Ni (OH)₂The influence of the structure of the material on the performance of the electrocatalytic oxygen evolution reaction can be prepared by regulating and controlling different solvent ratios to prepare four alpha-Ni (OH) with different structures (bud, flower, petal and sheet)₂A material.

Experiments show that the petal-like alpha-Ni (OH)₂The catalyst has high hydrogen and oxygen producing performance, high electrocatalytic activity and stability, which are attributable to small size and boundary activityThe more sites, the more active sites are exposed, the surface area is increased, the electrolyte permeation is facilitated, and meanwhile, the better toughness is achieved, and the electrocatalytic activity is obviously improved. In addition, in the previous reports on LDH synthesis, the solvent used was mainly water or a mixed solvent of water and alcohol, and few reports have used a mixed solvent of alcohol and azomethylpyrrolidone as a solvent.

[1]Zou X,Zhang Y.Noble Metal-Free Hydrogen Evolution Catalysts forWater Splitting.Chem.Soc.Rev.2015,44,5148-5180.

[2]Jiang J,Sun F,Zhou S,et al.Atomic-level insight into super-efficient electrocatalytic oxygen evolution on iron and vanadium co-dopednickel(oxy)hydroxide[J].Nature Communications,2018,9(1):2885.

[3]Ren J,Yuan G,Weng C,Chen L and Yuan Z.Uniquely integrated Fe-dopedNi(OH)₂nanosheets for highly efficient oxygen and hydrogen evolutionreactions[J].Nanoscale,2018,10,10620-10628.

[4]Luan C,Liu G,Liu Y,Yu L,Wang Y,Xiao Y,Qiao H,Dai Xand ZhangX.Structure Effects of 2D Materials onα-Nickel Hydroxide for Oxygen [email protected]@on[J].ACS Nano 2018,12,3875-3885.

Disclosure of Invention

The invention aims to provide a hill-shaped in-situ nickel-vanadium double hydroxide catalyst which is simple in preparation process, low in cost and easy to control in process, and a preparation method and application thereof.

In order to achieve the above object, the present invention adopts the following technical solutions.

A preparation method of a hill-shaped in-situ nickel-vanadium double metal hydroxide catalyst comprises the following steps:

the method comprises the following steps: pretreating foamed nickel;

step two: adding 62.92-70.78 mg of vanadium chloride and 66-78 mg of urea into a mixed solvent of alcohol and N-methylpyrrolidone, and uniformly stirring to obtain a solution A;

step three: soaking the foamed nickel treated in the step one in the solution A, pouring the foamed nickel into an inner reaction kettle, fixing the inner kettle in an outer kettle, placing the inner kettle in a homogeneous phase reactor, and carrying out solvothermal reaction at the rotating speed of 5-8 r/min and at the temperature of 115-125 ℃ for 23-25 h;

step four: after the reaction is finished, naturally cooling the reaction kettle to room temperature, then taking out the product foamed nickel after the reaction, and collecting the product foamed nickel after the product foamed nickel is alternately cleaned by water and alcohol;

step five: and drying the foamed nickel collected in the fourth step to obtain the hill-shaped in-situ nickel-vanadium double metal hydroxide catalyst.

Further, the step one, namely, the foam nickel pretreatment, comprises the steps of ultrasonically cleaning cut foam nickel of 1cm multiplied by 4.5cm in an acetone solution for 12-15 min, then pouring the foam nickel into prepared hydrochloric acid of 1-3 mol/L for ultrasonic cleaning for 5-8 min, finally alternately washing the foam nickel for 3-4 times by using absolute ethyl alcohol and ultrapure water respectively, and then drying the foam nickel for 10-15 h in vacuum at the temperature of 28-33 ℃.

Furthermore, the volume ratio of the azomethyl pyrrolidone to the alcohol in the mixed solvent in the second step is 1 (9-11).

Further, magnetic stirring is adopted in the stirring process in the second step, and the stirring time is 15-20 min.

Further, the solution A in the third step reacts in a reaction inner kettle, and the filling ratio is 60-64%.

Further, in the fourth step, the washing is carried out by alternately washing with ultrapure water and absolute ethyl alcohol for 3-4 times.

Further, the drying temperature in the fifth step is 70-75 ℃, and the time is 4-6 hours.

An application of hillock-shaped in-situ Ni-V bimetal hydroxide catalyst in hydrogen and oxygen evolution reaction under alkaline and neutral conditions.

Compared with the prior art, the method has the following specific beneficial effects:

1) compared with a synthesis strategy, the invention adopts a one-step solvothermal method, and has the characteristics of simple preparation process, low synthesis temperature, no need of large-scale equipment and harsh conditions and the like.

2) Ethanol is adopted as a solvent, and the solvent is non-toxic and non-corrosive; compared with the common water solvent, the water-soluble organic acid has lower boiling point, lower viscosity and surface tension, and low ionic strength, and has better reaction performance than water; the temperature of the reaction is determined depending on factors such as the activity temperature of the catalyst, the thermal effect of the reaction, the boiling points of the raw materials and products, and the thermal stability of the catalyst, and thus, the optimum reaction temperature may be different when the ratio of the raw materials to the solvent is changed.

3) In the invention, a small amount of nitrogen methyl pyrrolidone is added into a reaction solvent, and the control of the existing state of nickel vanadium hydroxide in the reaction is realized by strictly and synergistically controlling the volume of the nitrogen methyl pyrrolidone and alcohol, the concentration and proportion of a vanadium source and urea, the reaction time, the reaction temperature, the reaction filling ratio and other parameters.

4) Foam Nickel (NF) is not only a hard template agent, but also provides a nickel source. NF is a typical 3D porous foam metal, and the unique three-dimensional structure of the NF increases the loading capacity of the material and provides more reactive sites; the porous structure is beneficial to the transmission of substances and the timely overflow of gas; the use of expensive adhesives can be avoided to reduce contact resistance and improve conductivity. In addition, the integrated bone-meat connected structure is not only beneficial to improving the conductivity of the electrocatalyst, but also can enhance the mechanical stability of the electrode, thereby improving the activity and stability of the catalyst.

5) When the material is applied to a full-electrolysis water catalyst, the material shows good electrochemical activity. The NiV-LDH/NF electrodes of the invention were subjected to full-hydrolysis electrocatalytic tests in alkaline (pH 14) and neutral (pH 7) solutions, respectively. The catalytic test is carried out in an alkaline environment, and when the current density reaches 10mA/cm²The HER and OER overpotentials required were 208mV and 260mV, respectively. The catalyst is tested in a neutral environment, and when the current density reaches 10mA/cm²The required overpotentials for HER and OER were 324mV and 560mV, respectively. The result shows that the NiV-LDH/NF electrode has good full-hydrolytic performance under alkaline and neutral conditions.

Drawings

FIG. 1 is an X-ray diffraction (XRD) pattern of NiV-LDH/NF electrocatalyst prepared in example 1 of the present invention

FIG. 2 is a Scanning Electron Microscope (SEM) micrograph of NiV-LDH/NF electrocatalyst prepared according to example 1 of the present invention

FIG. 3 is a high magnification Scanning Electron Microscope (SEM) photograph of NiV-LDH/NF electrocatalyst prepared in example 1 of the present invention

FIG. 4 is a low power Transmission Electron Microscope (TEM) photograph of NiV-LDH/NF electrocatalyst prepared in example 1 of the present invention

FIG. 5 is a high-power Transmission Electron Microscope (TEM) photograph of NiV-LDH/NF electrocatalyst prepared in example 1 of the present invention

FIG. 6 is a graph of hydrogen production performance (HER) of Linear Sweep Voltammetry (LSV) curves under alkaline conditions for NiV-LDH/NF electrocatalyst prepared in example 1 of the present invention

FIG. 7 is a graph of oxygen evolution performance (OER) of Linear Sweep Voltammetry (LSV) curves under alkaline conditions for NiV-LDH/NF electrocatalyst prepared in example 1 of the present invention

FIG. 8 is a graph of oxygen evolution performance (HER) of Linear Sweep Voltammetry (LSV) curves under neutral conditions for NiV-LDH/NF electrocatalyst prepared in example 1 of the present invention

FIG. 9 is a graph of oxygen evolution performance (OER) of Linear Sweep Voltammetry (LSV) curves under neutral conditions for NiV-LDH/NF electrocatalyst prepared in example 1 of the present invention

Detailed Description

The present invention will be described in further detail with reference to the following examples, which are not intended to limit the invention thereto.