阅读说明：本技术 一种镍铁氧化物电催化剂的制备方法与应用 (Preparation method and application of nickel-iron oxide electrocatalyst ) 是由 崔小强 刘弘太 徐珊 许天翊 董易龙 武建栋 于 2021-10-28 设计创作，主要内容包括：本发明公开了一种镍铁氧化物组成的棒状纳米阵列结构电催化剂的制备方法与应用,获得了较为优秀的催化性能。本发明主要通过镍铁MOF前驱体作为自牺牲模板,空气气氛下退火后,制备出保持在MOF原始棒状形貌的同时,表面形成纳米片阵列结构的材料。该催化剂以泡沫镍为骨架,具有较好的导电性,棒状纳米阵列结构提高了催化剂的比表面积,暴露更多的活性位点,能够有效的促进析氧反应的发生。该电催化剂在碱性电解液中,在电流密度为10 mA/cm～(2)时,反应过电势为215mV,且稳定性很好,具有较好的应用前景。(The invention discloses a preparation method and application of a rodlike nano-array structure electrocatalyst composed of nickel-iron oxide, and relatively excellent catalytic performance is obtained. The method is mainly characterized in that a ferronickel MOF precursor is used as a self-sacrificial template, and after annealing is carried out in the air atmosphere, the material with the MOF original rod-like morphology and the nanosheet array structure formed on the surface is prepared. The catalyst takes the foam nickel as a framework, has better conductivity, and the rodlike nano array structure improves the specific surface area of the catalyst, exposes more active sites and can effectively promote the oxygen evolution reaction. The electrocatalyst is used in alkaline electrolyte at a current density of 10 mA/cm 2 And meanwhile, the overpotential of the reaction is 215mV, and the stability is good, so that the method has a good application prospect.)

1. The preparation method of the nickel-iron oxide electrocatalyst is characterized by comprising the following steps of:

(1) fully dissolving 99mg of 2, 5-dihydroxy terephthalic acid in a mixed solution of 10ml of N, N-dimethylformamide, 1.2ml of deionized water and 3.8ml of ethanol, then adding 99.4mg of ferrous chloride tetrahydrate, and fully stirring and dissolving;

(2) placing foamed nickel in an autoclave liner containing the solution prepared in the step (1) for hydrothermal reaction, reacting at 100 ℃ for 24 hours, naturally cooling to room temperature, taking out, and cleaning with deionized water and ethanol; then drying overnight in vacuum at 60 ℃ to obtain a NiFe-MOF/NF precursor;

(3) and (3) transferring the NiFe-MOF/NF dried in the step (2) into a muffle furnace, and annealing at 350 ℃ for 2 hours to obtain the ferronickel oxide electrocatalyst with the rod-shaped nano array structure.

2. The application of the rod-shaped nano array structure electrocatalyst composed of nickel-iron oxide prepared by the method of claim 1 in oxygen evolution reaction.

3. The application of claim 2, wherein a three-electrode system is adopted, the electrolyte is 1M KOH solution, the platinum sheet is used as a counter electrode, the silver-silver chloride electrode is used as a reference electrode, and the rod-shaped nano-array structured electrocatalyst composed of nickel-iron oxide is used as a working electrode to carry out oxygen evolution reaction.

Technical Field

The invention belongs to the technical field of catalysts, and particularly relates to a preparation method and application of a ferronickel oxide with a rod-like nano array structure.

Background

In order to solve the environmental problems associated with the gradual depletion of traditional fossil fuel resources and the combustion thereof, it is important to develop a cleaner, more efficient and sustainable new energy. The acquisition of new clean energy by the water electrolysis process has received a great deal of attention, including anodic Oxygen Evolution Reaction (OER) and cathodic Hydrogen Evolution Reaction (HER), whereas the overall water splitting system is limited by the slow kinetics of the OER reaction. The current commercial OER electrocatalyst is a noble metal Ir/Ru-based electrocatalyst, but the characteristics of low richness and high cost limit the wider commercial application of the OER electrocatalyst, and the development of a non-noble transition metal-based electrocatalyst with high cost benefit for replacing the noble metal-based electrocatalyst becomes a great research hotspot.

At present, the traditional metal oxide shows better intrinsic activity in OER reaction, the structure and the composition of the metal oxide can be regulated and controlled through the change of the metal components of the metal oxide, the intermetallic synergistic effect is improved, and the catalytic activity of the metal oxide is changed. However, the metal oxide has the problems of low exposure of oxygen evolution active sites, easy agglomeration in the catalytic process and the like which need to be solved.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a preparation method and application of a rod-shaped nanosheet array structure material consisting of nickel iron oxide. The electrocatalyst has a rod-shaped nanosheet array structure, has high specific surface area and excellent performances such as good conductivity and the like, and can be used for electrocatalytic oxygen evolution reaction.

The purpose of the invention is realized by the following technical scheme: a rod-shaped nanosheet array structure electrocatalyst composed of nickel-iron oxide is prepared by taking precursor nickel-iron MOF as a self-sacrificial template, annealing in an air atmosphere, and forming the nanosheet array structure electrocatalyst on the surface while keeping the rod-shaped morphology of the MOF. The catalyst takes foam nickel as a framework to form a ferronickel oxide nano material with a rod-like shape and a nano-sheet array structure on the surface, has better conductivity and high specific surface area, exposes more active sites, and is beneficial to O in the catalysis process by the nano-sheet array structure₂Desorption after generation, and stable and continuous operation of the catalyst is ensured。

The method accurately synthesizes complex nano-morphology, increases the active area of catalytic reaction, exposes more reaction active sites, greatly improves the activity of electrocatalytic oxygen evolution reaction of the nickel-iron oxide, simultaneously keeps long-term catalytic stability, and promotes the application of transition metal oxide series materials in the aspect of industrial catalysis.

Specifically, the scheme comprises the following steps:

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

(2) 99mg of 2, 5-dihydroxyterephthalic acid was sufficiently dissolved in a mixed solution of 10ml of N, N-dimethylformamide, 1.2ml of deionized water and 3.8ml of ethanol, and then 99.4mg of ferrous chloride tetrahydrate was added and sufficiently stirred to be dissolved.

(3) And (3) putting the dried foam nickel treated in the step (1) into an autoclave liner containing the solution prepared in the step (2) for hydrothermal reaction, reacting at 100 ℃ for 24 hours, naturally cooling to room temperature, taking out, and washing with deionized water and ethanol. And then dried overnight under vacuum at 60 ℃ to obtain the NiFe-MOF/NF precursor.

(4) And (4) transferring the NiFe-MOF/NF dried in the step (3) into a muffle furnace, and annealing at 350 ℃ for 2 hours to obtain the rod-shaped nano array structure electrocatalyst composed of the ferronickel oxide.

The invention also provides an application of the rod-shaped nano array structure electrocatalyst composed of the nickel-iron oxide in oxygen evolution reaction.

The catalysts were further evaluated for their OER catalytic performance in a three-electrode system. The electrolyte is 1M KOH solution, the platinum sheet is a counter electrode, the silver-silver chloride electrode is a reference electrode, and the rodlike nano-array structured electrocatalyst composed of nickel-iron oxide is a working electrode to perform oxygen evolution reaction.

The invention has the beneficial effects that: annealing in the air through the self-sacrifice template effect of the precursor of the ferronickel MOF, keeping the rod-shaped morphology of the MOF, and simultaneously forming a nanosheet array structure on the surface, so that the catalyst has a larger sizeThe specific surface area of the catalyst is larger than that of the active site, and excellent catalytic performance is shown. In alkaline electrolyte, when the overpotential is 215mV, the current density can reach 10 mA/cm²。

Drawings

FIG. 1 is an X-ray diffraction pattern (XRD) of sample one (NiFe-MOF/NF) and sample two (rod-shaped nanosheet array structure electrocatalyst composed of nickel iron oxide) prepared in example 1.

FIG. 2 is a Scanning Electron Micrograph (SEM) of sample I (NiFe-MOF/NF) and sample II (rod-shaped nanosheet array structure electrocatalyst composed of nickel iron oxide) prepared in example 1.

FIG. 3 is the electrochemical polarization curves of sample one (NiFe-MOF/NF) and sample two (rod-shaped nanosheet array structure electrocatalyst composed of nickel iron oxide) as oxygen evolution reaction catalysts 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:

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

(2) 99mg of 2, 5-dihydroxyterephthalic acid was sufficiently dissolved in a mixed solution of 10ml of N, N-dimethylformamide, 1.2ml of deionized water and 3.8ml of ethanol, and then 99.4mg of ferrous chloride tetrahydrate was added and sufficiently stirred to be dissolved.

(3) And (3) putting the dried foam nickel treated in the step (1) into an autoclave liner containing the solution prepared in the step (2) for hydrothermal reaction, reacting at 100 ℃ for 24 hours, naturally cooling to room temperature, taking out, and washing with deionized water and ethanol. Followed by vacuum drying at 60 ℃ overnight to give the NiFe-MOF/NF precursor (sample one).

(4) And (4) transferring the NiFe-MOF/NF dried in the step (3) into a muffle furnace, and annealing at 350 ℃ for 2 hours to obtain the rod-shaped nano array structure electrocatalyst (sample II) composed of the ferronickel oxide.

FIG. 1 is the X-ray diffraction pattern of sample I (NiFe-MOF/NF) and sample II (rod-shaped nanosheet array structure electrocatalyst composed of nickel-iron oxide) prepared in this example, from which it can be seen that sample I has the characteristic peak of NiFe-MOF, and NiFeO converted on the basis of NiFe-MOF/NF_xthe/NF has characteristic peaks of nickel iron oxide.

Fig. 2 is a Scanning Electron Microscope (SEM) image of a first sample (NiFe-MOF/NF) and a second sample (ni-fe oxide-based rod-shaped nanosheet array structure electrocatalyst), which are prepared in this example, wherein NiFe-MOF in the first sample has a rod-shaped structure with a flat and smooth surface, and the second sample can obviously observe the rod-shaped nanometer array structure, and a larger specific surface area exposes more reactive sites.

Example 2:

sample one (NiFe-MOF/NF) and sample two (rod-shaped nanosheet array structure electrocatalyst composed of nickel iron oxide) prepared in example 1 were further evaluated for their OER catalytic performance in a three-electrode system. In the electrolyte of 1M KOH solution, taking a sample I (NiFe-MOF/NF) with the size of 1 cm multiplied by 1 cm as a working electrode, a platinum sheet as a counter electrode and a silver-silver chloride electrode as a reference electrode, and carrying out oxygen evolution reaction. Then, in the electrolyte of 1M KOH solution, taking a sample II (a rodlike nanosheet array structure electrocatalyst formed by nickel-iron oxide) with the size of 1 cm multiplied by 1 cm as a working electrode, a platinum sheet as a counter electrode and a silver-silver chloride electrode as a reference electrode, and carrying out oxygen evolution reaction.

The platinum sheet is used as a working electrode, the platinum sheet is used as a counter electrode, and the silver-silver chloride electrode is used as a reference electrode, so that oxygen evolution reaction is carried out. Then, in the electrolyte of 1M KOH solution, taking a sample II (a rodlike nanosheet array structure electrocatalyst formed by nickel-iron oxide) with the size of 1 cm multiplied by 1 cm as a working electrode, a platinum sheet as a counter electrode and a silver-silver chloride electrode as a reference electrode, and carrying out oxygen evolution reaction.

FIG. 3 shows the structure of a rod-shaped nanosheet array composed of NiFe-MOF/NF and NiFe-Fe-oxide as samples one and two in example 2Catalyst) as electrochemical polarization curves of the oxygen evolution reaction catalysts, respectively. Sample I (NiFe-MOF/NF) is used as an oxygen evolution reaction catalyst, and the system reaches 10 mA/cm when the measurement is carried out at the scanning speed of 10mV/S²The overpotential at the current density of (1) was 280 mV. A second sample (a rodlike nano-sheet array structure electro-catalyst consisting of nickel-iron oxide) is used as an oxygen evolution reaction catalyst, and the system reaches 10 mA/cm when the measurement is carried out at the scanning speed of 10mV/S²The overpotential is only 215mV at the current density of (1).

The invention realizes the self-sacrificial template function of the precursor of the ferronickel MOF, the ferronickel MOF is annealed in the air, the material keeps the rod-shaped morphology of the MOF, and simultaneously, the surface forms a nanometer sheet array structure, the catalyst prepares the rod-shaped nanometer sheet array structure electrocatalyst composed of the ferronickel oxide, the catalyst takes foam nickel as a framework to form the ferronickel oxide nanometer material with the rod-shaped morphology and the surface with the nanometer sheet array structure, the catalyst has better conductivity and high specific surface area, more active sites are exposed, and the nanometer sheet array structure is beneficial to O in the catalysis process₂The desorption after the generation ensures the stable and continuous work of the catalyst. The electrocatalyst shows excellent catalytic activity in an alkaline oxygen evolution catalytic reaction, and promotes further application of a transition metal oxide, namely a nickel-iron oxide, in the field of water decomposition.