CN112121828A

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Info

Publication number: CN112121828A
Application number: CN202010648040.2A
Authority: CN
Inventors: 姚亚东; 田文丽; 张节
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2020-07-07
Filing date: 2020-07-07
Publication date: 2020-12-25

Abstract

Translated fromChinese

本发明公开了一种原位生长于碳布上具有纳米线阵列核壳结构在CoP纳米线上电沉积NiCo‑LDH纳米片（CoP@NiCo‑LDH/CC）的制备方法。以六水合硝酸钴为钴源，采用氟化铵为氟源并和尿素共同调控前驱体溶液的pH值，碳布为导电基底，采用水热法先制备Co(OH)F/CC前驱，再以NaH₂PO₂·H₂O为磷源，采用低温保形磷化法以Co(OH)F/CC为前驱以合成CoP/CC，再以六水合硝酸镍和六水合硝酸钴为电解液，甘汞电极为参比电极，CoP/CC为工作电极，铂片为对电极，采用电沉积法以合成CoP@NiCo‑LDH/CC，将其用于水氧化反应电催化剂，在1 M KOH电解质中表现出优异的催化活性（η_{20mA cm–2}=259 mV），大幅优于CoP/CC（η_{20mA cm–2}=358 mV）和NiCo‑LDH/CC（η_{20mA cm–2}=323 mV）。The invention discloses a preparation method for electrodepositing NiCo-LDH nanosheets (CoP@NiCo-LDH/CC) on CoP nanowires with a nanowire array core-shell structure grown on carbon cloth in situ. Cobalt nitrate hexahydrate was used as the cobalt source, ammonium fluoride was used as the fluorine source and the pH value of the precursor solution was adjusted together with urea, and the carbon cloth was used as the conductive substrate. Using NaH₂ PO₂ ·H₂ O as the phosphorus source, the low temperature conformal phosphating method was used to synthesize CoP/CC with Co(OH)F/CC as the precursor, and then nickel nitrate hexahydrate and cobalt nitrate hexahydrate were used as electrolytes , the calomel electrode is the reference electrode, the CoP/CC is the working electrode, and the platinum sheet is the counter electrode. CoP@NiCo‑LDH/CC was synthesized by electrodeposition method, and it was used as an electrocatalyst for water oxidation reaction at 1 M KOH. It exhibits excellent catalytic activity in the electrolyte (η_{20mA cm–2} = 259 mV), which is significantly better than CoP/CC (η_{20mA cm–2} = 358 mV) and NiCo‑LDH/CC (η_{20mA cm–2} = 323 mV) ).

Description

Translated fromChinese

电沉积法制备水滑石基三维核壳异质纳米阵列水氧化电催化剂Preparation of Hydrotalcite-Based Three-dimensional Core-Shell Heterogeneous Nanoarrays for Water Oxidation Electrocatalysts by Electrodepositionchemical

技术领域technical field

本发明涉及纳米阵列核壳结构CoP@NiCo-LDH纳米复合物的制备和应用于电催化碱性水氧化反应的方法，特别是涉及先在碳布（CC）上原位生长Co(OH)F前驱，再通过低温保形磷化法处理Co(OH)F/CC以制备CoP/CC，再在CoP/CC上电沉积NiCo-LDH以制备CoP@NiCo-LDH/CC，以及该材料在电催化换能领域中的应用。仅采用简单可控、环保经济的合成方法便可制备高性能水氧化电催化剂。The invention relates to a method for preparing a nano-array core-shell structure CoP@NiCo-LDH nanocomposite and applying it to an electrocatalytic alkaline water oxidation reaction, in particular to in-situ growth of Co(OH)F on carbon cloth (CC) Precursor, then treated Co(OH)F/CC by low temperature conformal phosphating method to prepare CoP/CC, and then electrodeposited NiCo-LDH on CoP/CC to prepare CoP@NiCo-LDH/CC, and the material was electro-deposited. Applications in the field of catalytic conversion. High-performance electrocatalysts for water oxidation can be prepared using only a simple, controllable, environmentally friendly and economical synthesis method.

背景技术Background technique

全球环境的日渐恶化及传统化石燃料的不断消耗迫使人们不断寻求清洁可持续的能源，氢能因其高能量密度及环境友好性等优点被认为是化石燃料的理想替代品（Nat.Chem., 2009, 1, 112-117,Science, 2004, 305, 972-974）。电解水是一种简单的制氢方法，包括析氧反应（OER）和析氢反应（HER）两个半反应，其中析氧反应涉及四电子传递过程，是一个动力学缓慢的过程，被认为是电解水的瓶颈。因此，急需高效水氧化电催化剂以实现较快的动力学过程及减小较大的过电位（Science, 2011, 334, 1383-1385,EnergyEnviron. Sci., 2013, 6, 2921-2924）。目前，氧化钌和氧化铱等贵金属基电催化剂被认为是最好的水氧化电催化剂，但其高成本及低储量限制了其大规模的应用（J. Phys.Chem. Lett., 2012, 3, 339–404）。因此，开发非贵金属基的水氧化电催化剂实现高效稳定的水氧化电催化反应尤其重要和紧迫。The deteriorating global environment and the continuous consumption of traditional fossil fuels force people to continuously seek clean and sustainable energy. Hydrogen energy is considered to be an ideal substitute for fossil fuels due to its high energy density and environmental friendliness (Nat.Chem ., 2009, 1, 112-117,Science , 2004, 305, 972-974). Water electrolysis is a simple method for hydrogen production, including two half-reactions, oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Bottleneck of electrolyzed water. Therefore, high-efficiency electrocatalysts for water oxidation are urgently needed to achieve faster kinetic processes and reduce larger overpotentials (Science , 2011, 334, 1383-1385,EnergyEnviron. Sci. , 2013, 6, 2921-2924). Currently, noble metal-based electrocatalysts such as ruthenium oxide and iridium oxide are considered to be the best electrocatalysts for water oxidation, but their high cost and low reserves limit their large-scale applications (J. Phys.Chem. Lett. , 2012, 3 , 339–404). Therefore, it is particularly important and urgent to develop non-precious metal-based electrocatalysts for water oxidation to achieve efficient and stable electrocatalytic reactions for water oxidation.

层状双金属氢氧化物（LDHs）由于其低成本，高活性且易于扩展的层间结构等优点，在催化和储能方面都具有很大的应用前景（Energy Environ. Sci., 2017, 10, 1820–1827）。特别是镍基LDHs，因其易于调整的化学组分，高活性等展现出优异的水氧化电催化活性（Chem. Rev., 2016, 116, 14120–14136,Sci. Rep., 2016, 6, 18737–18746）。但是，大多数镍基LDHs都是团聚颗粒，具有有限的比表面积和较差的稳定性（Electrochim.Acta, 2014, 135, 513–518）。为克服这些缺点，已采用了各种策略，其中界面工程被认为是最重要和最有效的方法之一（Adv. Funct. Mater., 2013, 23, 3513–3518）。特别是核-壳异质结构，由于其结构相互作用，电子耦合，较大的表面积以及与电解质的紧密接触，表现出比其单相结构更强的电催化活性（ACS Appl. Energy Mater., 2018, 1, 3929−3936）。此外，在碳布上生长的纳米阵列结构由于其有效的电子转移，高电导率及大表面积显示出优异的电解水性能（Nanoscale, 2017, 9, 16632–16637,Langmuir, 2015, 31,5220–5227）。因此，在碳布上构建水滑石基核-壳纳米阵列材料有望获得很好的电化学性能，这鲜有报道。Layered double metal hydroxides (LDHs) have great application prospects in both catalysis and energy storage due to their low cost, high activity, and easily extended interlayer structure (Energy Environ. Sci. , 2017, 10 , 1820–1827). In particular, nickel-based LDHs exhibit excellent electrocatalytic activity for water oxidation due to their easily tunable chemical composition, high activity, etc. (Chem. Rev. , 2016, 116, 14120–14136,Sci. Rep. , 2016, 6, 18737–18746). However, most Ni-based LDHs are agglomerated particles with limited specific surface area and poor stability (Electrochim.Acta , 2014, 135, 513–518). To overcome these shortcomings, various strategies have been adopted, among which interface engineering is considered to be one of the most important and effective methods (Adv. Funct. Mater. , 2013, 23, 3513–3518). In particular, core-shell heterostructures exhibit stronger electrocatalytic activity than their single-phase structures due to their structural interactions, electronic coupling, larger surface area, and close contact with the electrolyte (ACS Appl. Energy Mater. , 2018, 1, 3929−3936). In addition, nanoarray structures grown on carbon cloth exhibit excellent water electrolysis performance due to their efficient electron transfer, high electrical conductivity and large surface area (Nanoscale , 2017, 9, 16632–16637,Langmuir , 2015, 31, 5220– 5227). Therefore, the construction of hydrotalcite-based core-shell nanoarray materials on carbon cloth is expected to achieve good electrochemical performance, which is rarely reported.

本发明的目的是提供一种水滑石基三维核壳异质纳米阵列的简单可控，环保经济的合成方法，并将其用作高活性的水氧化电催化剂。The purpose of the present invention is to provide a simple, controllable, environment-friendly and economical synthesis method of hydrotalcite-based three-dimensional core-shell heterogeneous nanoarrays, and to use it as a highly active electrocatalyst for water oxidation.

本发明的基本构思是：以六水合硝酸钴为钴源，采用氟化铵为氟源并和尿素共同调控前驱体溶液的pH值，碳布为导电基底，采用水热法先制备Co(OH)F/CC前驱，再以NaH₂PO₂·H₂O为磷源，采用低温保形磷化法以Co(OH)F/CC为前驱以合成CoP/CC，再以六水合硝酸镍和六水合硝酸钴为电解液，甘汞电极为参比电极，CoP/CC为工作电极，铂片为对电极，采用电沉积法以合成CoP@NiCo-LDH/CC，并将其用于水氧化反应电催化剂。The basic concept of the present invention is as follows: using cobalt nitrate hexahydrate as the cobalt source, using ammonium fluoride as the fluorine source and regulating the pH value of the precursor solution together with urea, carbon cloth as the conductive substrate, and using the hydrothermal method to first prepare Co(OH )F/CC precursor, and then using NaH₂ PO₂ ·H₂ O as the phosphorus source, the low temperature conformal phosphating method was used to synthesize CoP/CC with Co(OH)F/CC as the precursor, and then nickel nitrate hexahydrate and Cobalt nitrate hexahydrate was used as electrolyte, calomel electrode as reference electrode, CoP/CC as working electrode, and platinum sheet as counter electrode. Electrodeposition method was used to synthesize CoP@NiCo-LDH/CC and use it for water oxidation Reacting Electrocatalysts.

发明内容SUMMARY OF THE INVENTION

本发明提出一种简单可控，环保经济的水热法，低温保形磷化法及电沉积法以原位制备三维核壳异质结构CoP@NiCo-LDH纳米阵列，并将其作为高活性的水氧化电催化剂。The present invention proposes a simple, controllable, environmentally friendly and economical hydrothermal method, low-temperature conformal phosphating method and electrodeposition method to in situ prepare a three-dimensional core-shell heterostructure CoP@NiCo-LDH nanoarray, and use it as a highly active water oxidation electrocatalyst.

本发明主要解决的技术问题是克服一般LDHs基水氧化电催化剂由于稳定性和导电性较差而导致的活性位点利用率不高和催化活性降低的缺点，避免了常规粉末电极制备过程中由于导电剂和粘结剂的引入而导致活性位点被覆盖和接触电阻增大，制备了原位生长于碳布上具有纳米线阵列核壳结构在CoP纳米线上电沉积NiCo-LDH纳米片（CoP@NiCo-LDH/CC）水氧化电催化剂，利用三维核壳异质纳米阵列的形成降低系列电阻，暴露更多活性位点和促进电解质和析出气体的扩散，作为水氧化电催化剂，展示出极高的电化学换能性质。具体来讲，本发明是以六水合硝酸钴为钴源，采用氟化铵为氟源并和尿素共同调控前驱体溶液的pH值，碳布为导电基底，采用水热法先制备Co(OH)F/CC前驱，再以NaH₂PO₂·H₂O为磷源，采用低温保形磷化法以Co(OH)F/CC为前驱以合成CoP/CC，再以六水合硝酸镍和六水合硝酸钴为电解液，甘汞电极为参比电极，CoP/CC为工作电极，铂片为对电极，采用电沉积法以合成CoP@NiCo-LDH/CC三维核壳异质纳米阵列水氧化电催化剂，展现出低的水氧化反应过电位和塔菲尔斜率，以及优异的循环稳定性能。The main technical problem solved by the present invention is to overcome the shortcomings of low active site utilization and reduced catalytic activity of general LDHs-based water oxidation electrocatalysts due to poor stability and conductivity, and to avoid the problems in the preparation process of conventional powder electrodes. The introduction of conductive agent and binder leads to the coverage of active sites and the increase of contact resistance. NiCo-LDH nanosheets with nanowire array core-shell structure grown on carbon cloth in situ were prepared by electrodeposition on CoP nanowires ( CoP@NiCo-LDH/CC) water oxidation electrocatalyst, utilizing the formation of 3D core-shell heteronanoarrays to reduce series resistance, expose more active sites and promote diffusion of electrolyte and evolved gas, as water oxidation electrocatalyst, exhibiting Extremely high electrochemical transduction properties. Specifically, the present invention uses cobalt nitrate hexahydrate as the cobalt source, ammonium fluoride as the fluorine source and controls the pH value of the precursor solution together with urea, carbon cloth as the conductive substrate, and firstly prepares Co(OH) by hydrothermal method. )F/CC precursor, and then using NaH₂ PO₂ ·H₂ O as the phosphorus source, the low temperature conformal phosphating method was used to synthesize CoP/CC with Co(OH)F/CC as the precursor, and then nickel nitrate hexahydrate and Using cobalt nitrate hexahydrate as electrolyte, calomel electrode as reference electrode, CoP/CC as working electrode, and platinum sheet as counter electrode, electrodeposition method was used to synthesize CoP@NiCo-LDH/CC three-dimensional core-shell heterogeneous nanoarray water. Oxidative electrocatalysts exhibit low overpotentials and Tafel slopes for water oxidation reactions, as well as excellent cycling stability.

本发明具体工序步骤如下：The concrete process steps of the present invention are as follows:

(1). 备料：Co (NO₃)₂·6H₂O（0.582 g），CO(NH₂)₂（0.61 g）和NH₄F（0.186 g），溶解于40mL去离子水中，搅拌均匀，一片尺寸为2×4 cm²的碳布（CC），对其先使用69 %浓硝酸在120℃下处理2 h，后分别使用去离子水和无水乙醇超声10 min进行预处理；(1). Preparation: Co(NO₃ )₂ ·6H₂ O (0.582 g), CO(NH₂ )₂ (0.61 g) and NH₄ F (0.186 g), dissolved in 40 mL of deionized water, stirred well, A piece of carbon cloth (CC) with a size of 2 × 4 cm² was first treated with 69 % concentrated nitric acid at 120 °C for 2 h, and then pretreated with deionized water and absolute ethanol for 10 min by ultrasonic wave respectively;

(2). 水热反应：将步骤（1）中的溶液和处理好的CC移至50 mL聚四氟乙烯高压釜中，并密封高压釜，将其放置在真空干燥箱中，于120 ℃下反应6 h；(2). Hydrothermal reaction: transfer the solution in step (1) and the treated CC to a 50 mL polytetrafluoroethylene autoclave, seal the autoclave, and place it in a vacuum drying oven at 120 °C The next reaction is 6 h;

(3). 洗涤干燥：待步骤（2）的反应完成后，置聚四氟乙烯高压釜于空气中冷却至室温，取出被红色物质均匀覆盖的CC，用去离子水和无水乙醇先后超声洗涤3-5次后于60 ℃下真空干燥2 h，制得Co(OH)F/CC前驱；(3). Washing and drying: After the reaction in step (2) is completed, set the polytetrafluoroethylene autoclave to cool to room temperature in the air, take out the CC evenly covered by the red substance, and use deionized water and anhydrous ethanol to sonicate successively After washing 3-5 times, vacuum drying at 60 °C for 2 h to obtain Co(OH)F/CC precursor;

(4). 备料：一片步骤（3）所获得的Co(OH)F/CC前驱，NaH₂PO₂·H₂O（摩尔比Co:P =1:3）；(4). Material preparation: a piece of Co(OH)F/CC precursor obtained in step (3), NaH₂ PO₂ ·H₂ O (molar ratio Co:P = 1:3);

(5). 低温保形磷化：将步骤（4）中的NaH₂PO₂·H₂O和步骤（3）所制备的Co(OH)F/CC前驱分别放在两个瓷舟里置于管式气氛炉中，装有NaH₂PO₂·H₂O的瓷舟放在管的上游，在氩气气氛下升温至300 ℃并保温2 h，然后在氩气气氛下冷却至室温，制得黑色的CoP/CC；(5). Low-temperature conformal phosphating: place the NaH₂ PO₂ ·H₂ O in step (4) and the Co(OH)F/CC precursor prepared in step (3) in two ceramic boats respectively. In a tubular atmosphere furnace, a porcelain boat filled with NaH₂ PO₂ ·H₂ O was placed upstream of the tube, heated to 300 °C under an argon atmosphere and kept for 2 h, and then cooled to room temperature under an argon atmosphere. Obtained black CoP/CC;

(6). 备料：Co (NO₃)₂·6H₂O（0.15 M），Ni(NO₃)₂·6H₂O（0.15 M），甘汞电极，铂片，一片步骤（5）所获得的CoP/CC；(6). Materials: Co(NO₃ )₂ ·6H₂ O (0.15 M), Ni(NO₃ )₂ ·6H₂ O (0.15 M), calomel electrode, platinum sheet, one piece obtained in step (5) CoP/CC;

(7). 电沉积：将步骤（6）的溶液作为电解液，甘汞电极为参比电极，铂片为对电极，步骤（5）制得的CoP/CC为工作电极，采用三电极系统在CoP/CC上电沉积NiCo-LDH，电沉积电位为 -1.0 V vs SCE，时间为180-220 s；(7). Electrodeposition: the solution in step (6) is used as the electrolyte, the calomel electrode is used as the reference electrode, the platinum sheet is used as the counter electrode, the CoP/CC obtained in step (5) is used as the working electrode, and a three-electrode system is used. Electrodeposition of NiCo-LDH on CoP/CC with electrodeposition potential of -1.0 V vs SCE for 180-220 s;

(8). 洗涤干燥：待步骤（7）电沉积结束后，取出被产物均匀覆盖的CC，用去离子水洗涤3-5次后于40 ℃下真空干燥24 h，制得CoP@NiCo-LDH/CC；(8). Washing and drying: After the electrodeposition in step (7), take out the CC evenly covered by the product, wash it with deionized water for 3-5 times, and then vacuum dry it at 40 °C for 24 h to obtain CoP@NiCo- LDH/CC;

(9). 表征及电化学测试：采用XRD，SEM，EDX，TEM和XPS表征CoP@NiCo-LDH/CC材料的结构和微观形貌，并使用DH7000电化学工作站，评价CoP@NiCo-LDH/CC的水氧化反应过电位，塔菲尔斜率和循环稳定性能，评价结果见表一。(9). Characterization and electrochemical tests: XRD, SEM, EDX, TEM and XPS were used to characterize the structure and microscopic morphology of CoP@NiCo-LDH/CC materials, and DH7000 electrochemical workstation was used to evaluate CoP@NiCo-LDH/CC materials. The water oxidation reaction overpotential, Tafel slope and cycle stability performance of CC are shown in Table 1.

本发明所需的反应装置简单，仅需聚四氟乙烯高压反应釜，真空干燥箱及管式气氛炉；所涉及的原料来源广泛，价格低廉；操作步骤简单，制备周期短，直接通过水热反应，低温保形磷化及电沉积即可获得所需的催化剂材料，如此设计的CoP@NiCo-LDH/CC具有三维核壳异质纳米阵列结构，将其用作水氧化电催化剂，在1 M KOH电解质中表现出优异的催化活性（η_{20 mA cm–2} = 259 mV，塔菲尔斜率 = 98 mV dec^–1）和突出的循环稳定性能。The reaction device required by the invention is simple, and only needs a polytetrafluoroethylene high-pressure reaction kettle, a vacuum drying box and a tubular atmosphere furnace; the raw materials involved are widely sourced, and the price is low; the operation steps are simple, the preparation period is short, and the hydrothermal The desired catalyst materials can be obtained by reaction, low-temperature conformal phosphating and electrodeposition. The thus designed CoP@NiCo-LDH/CC has a three-dimensional core-shell heterogeneous nanoarray structure, which is used as an electrocatalyst for water oxidation. It exhibits excellent catalytic activity (η_{20 mA cm–2} = 259 mV, Tafel slope = 98 mV dec^-1 ) and outstanding cycling stability in M KOH electrolyte.

本发明与现有技术及合成路线相比，具有如下的优点和有益效果：Compared with the prior art and the synthetic route, the present invention has the following advantages and beneficial effects:

1．CoP@NiCo-LDH/CC制备过程简单可控，环保经济，且反应条件温和，反应周期短；1. The preparation process of CoP@NiCo-LDH/CC is simple and controllable, environmentally friendly and economical, and the reaction conditions are mild and the reaction cycle is short;

2．CoP@NiCo-LDH/CC表现为三维核壳异质纳米阵列，可避免引入其他添加剂，有效减小系列电阻，简化催化剂电极的制备过程，并且能提供更多暴露的活性位点，促进电解质和析出气体的扩散；2. CoP@NiCo-LDH/CC behaves as a three-dimensional core-shell heterogeneous nanoarray, which can avoid the introduction of other additives, effectively reduce the series resistance, simplify the preparation process of catalyst electrodes, and can provide more exposed active sites, promote electrolyte and Diffusion of evolved gases;

3．CoP@NiCo-LDH/CC水氧化电催化剂展示出优异的电化学换能性质，拥有低的水氧化反应过电位（η_{20 mA cm–2} = 259 mV）和突出的循环稳定性能。3. The CoP@NiCo-LDH/CC water oxidation electrocatalyst exhibits excellent electrochemical energy conversion properties with low water oxidation reaction overpotential (η_{20 mA cm–2} = 259 mV) and outstanding cycling stability.

附图说明Description of drawings

1. 图1是CoP/CC和CoP@NiCo-LDH/CC的XRD图；1. Figure 1 is the XRD pattern of CoP/CC and CoP@NiCo-LDH/CC;

2. 图2是 CoP@NiCo-LDH/CC的EDX图；2. Figure 2 is the EDX diagram of CoP@NiCo-LDH/CC;

3. 图3是CoP@NiCo-LDH/CC的SEM图；3. Figure 3 is the SEM image of CoP@NiCo-LDH/CC;

4. 图4是CoP/CC，CoP@NiCo-LDH/CC，NiCo-LDH/CC，CC及Ru₂O/CC扫描伏安（LSV）曲线；4. Figure 4 is the scanning voltammetry (LSV) curves of CoP/CC, CoP@NiCo-LDH/CC, NiCo-LDH/CC, CC and Ru₂ O/CC;

5. 图5是CoP/CC，CoP@NiCo-LDH/CC，NiCo-LDH/CC及Ru₂O/CC的塔菲尔（Tafel）曲线；5. Figure 5 is the Tafel curve of CoP/CC, CoP@NiCo-LDH/CC, NiCo-LDH/CC and Ru₂ O/CC;

6. 图6是CoP@NiCo-LDH/CC经1000次循环伏安测试前后的LSV曲线。6. Figure 6 shows the LSV curves of CoP@NiCo-LDH/CC before and after 1000 cyclic voltammetry tests.

具体实施方式Detailed ways

实例一Example 1

(4). 备料：一片步骤（3）所获得的Co(OH)F/CC前驱，NaH₂PO₂·H₂O（摩尔比Co:P = 1:3）；(4). Material preparation: a piece of Co(OH)F/CC precursor obtained in step (3), NaH₂ PO₂ ·H₂ O (molar ratio Co:P = 1:3);

(7). 电沉积：将步骤（6）的溶液作为电解液，甘汞电极为参比电极，铂片为对电极，步骤（5）制得的CoP/CC为工作电极，采用三电极系统在CoP/CC上电沉积NiCo-LDH，电沉积电位为-1.0 V vs SCE，时间为180 s；(7). Electrodeposition: the solution in step (6) is used as the electrolyte, the calomel electrode is used as the reference electrode, the platinum sheet is used as the counter electrode, the CoP/CC obtained in step (5) is used as the working electrode, and a three-electrode system is used. Electrodeposition of NiCo-LDH on CoP/CC with electrodeposition potential of -1.0 V vs SCE for 180 s;

实例二Example 2

(7). 电沉积：将步骤（6）的溶液作为电解液，甘汞电极为参比电极，铂片为对电极，步骤（5）制得的CoP/CC为工作电极，采用三电极系统在CoP/CC上电沉积NiCo-LDH，电沉积电位为-1.0 V vs SCE，时间为200 s；(7). Electrodeposition: the solution in step (6) is used as the electrolyte, the calomel electrode is used as the reference electrode, the platinum sheet is used as the counter electrode, the CoP/CC obtained in step (5) is used as the working electrode, and a three-electrode system is used. Electrodeposition of NiCo-LDH on CoP/CC with electrodeposition potential of -1.0 V vs SCE for 200 s;

(9).表征及电化学测试：采用XRD，SEM，EDX，TEM和XPS表征CoP@NiCo-LDH/CC材料的结构和微观形貌，并使用DH7000电化学工作站，评价CoP@NiCo-LDH/CC的水氧化反应过电位，塔菲尔斜率和循环稳定性能，评价结果见表一。(9). Characterization and electrochemical test: The structure and microstructure of CoP@NiCo-LDH/CC were characterized by XRD, SEM, EDX, TEM and XPS, and the CoP@NiCo-LDH/CC was evaluated by DH7000 electrochemical workstation. The water oxidation reaction overpotential, Tafel slope and cycle stability performance of CC are shown in Table 1.

实例三Example three

(7). 电沉积：将步骤（6）的溶液作为电解液，甘汞电极为参比电极，铂片为对电极，步骤（5）制得的CoP/CC为工作电极，采用三电极系统在CoP/CC上电沉积NiCo-LDH，电沉积电位为-1.0 V vs SCE，时间为220 s；(7). Electrodeposition: the solution in step (6) is used as the electrolyte, the calomel electrode is used as the reference electrode, the platinum sheet is used as the counter electrode, the CoP/CC obtained in step (5) is used as the working electrode, and a three-electrode system is used. Electrodeposition of NiCo-LDH on CoP/CC with electrodeposition potential of -1.0 V vs SCE for 220 s;

表一各实例CoP@NiCo-LDH/CC的水氧化电催化性能评价Table 1 Evaluation of electrocatalytic performance for water oxidation of CoP@NiCo-LDH/CC for each example

Claims

1. The method for preparing the hydrotalcite-based three-dimensional core-shell heterogeneous nano-array water oxidation electrocatalyst by the electrodeposition method with Carbon Cloth (CC) as a conductive substrate is characterized in that cobalt nitrate hexahydrate is used as a nickel source, ammonium fluoride is used as a fluorine source, the pH value of a precursor solution is regulated and controlled together with urea, the molar ratio of the ammonium fluoride to the urea is 1:2, a Co (OH) F/CC precursor is synthesized by a hydrothermal method, and NaH is used for₂PO₂·H₂O is taken as a phosphorus source, the molar ratio of Co to P is 1:3, a CoP nanowire array (CoP/CC) is prepared by taking Co (OH) F/CC as a precursor by adopting a low-temperature conformal phosphorization method, nickel nitrate hexahydrate and cobalt nitrate hexahydrate are taken as electrolyte, the molar ratio of nickel and cobalt elements is 1:1, a calomel electrode is taken as a reference electrode, CoP/CC is taken as a working electrode, a platinum sheet is taken as a counter electrode, and the three-dimensional core-shell CoP @ NiCo-LDH/CC heterogeneous nanoarray water oxidation electrocatalyst is synthesized by adopting an electrodeposition method.

2. The method of claim 1, comprising the steps of:

preparing materials: co (NO)₃)₂·6H₂O（0.582 g），CO(NH₂)₂(0.61 g) and NH₄F (0.186 g), dissolved in 40 mL of deionized water, stirred well, one piece size 2X 4 cm²The Carbon Cloth (CC) is firstly treated by 69 percent concentrated nitric acid at 120 ℃ for 2 hours and then is pre-treated by respectively using deionized water and absolute ethyl alcohol for 10 min by ultrasonic treatment;

hydrothermal reaction: transferring the solution in the step (1) and the treated CC into a 50 mL polytetrafluoroethylene high-pressure autoclave, sealing the high-pressure autoclave, placing the high-pressure autoclave in a vacuum drying oven, and reacting for 6 h at 120 ℃;

washing and drying: after the reaction in the step (2) is finished, placing a polytetrafluoroethylene high-pressure autoclave in air to be cooled to room temperature, taking out the CC uniformly covered by the red substance, ultrasonically washing the CC for 3 to 5 times by using deionized water and absolute ethyl alcohol sequentially, and then drying the CC in vacuum at 60 ℃ for 2 hours to prepare a Co (OH) F/CC precursor;

preparing materials: a piece of Co (OH) F/CC precursor, NaH, obtained in step (3)₂PO₂·H₂O (molar ratio Co: P =1: 3);

low-temperature conformal phosphorization: adding NaH in the step (4)₂PO₂·H₂O and the Co (OH) F/CC precursor prepared in the step (3) are respectively put in two porcelain boats and put in a tubular atmosphere furnace filled with NaH₂PO₂·H₂Placing a porcelain boat of O on the upstream of the tube, heating to 300 ℃ in an argon atmosphere, preserving heat for 2 hours, and then cooling to room temperature in the argon atmosphere to obtain black CoP/CC;

preparing materials: co (NO)₃)₂·6H₂O（0.15 M），Ni(NO₃)₂·6H₂O (0.15M), a calomel electrode, a platinum sheet, and a piece of CoP/CC obtained in the step (5);

electro-deposition: taking the solution in the step (6) as an electrolyte, taking a calomel electrode as a reference electrode, taking a platinum sheet as a counter electrode, taking the CoP/CC prepared in the step (5) as a working electrode, and electrodepositing NiCo-LDH on the CoP/CC by adopting a three-electrode system, wherein the electrodeposition potential is-1.0V vs SCE, and the time is 180-;

washing and drying: after the electrodeposition in the step (7) is finished, taking out the CC uniformly covered by the product, washing the CC for 3 to 5 times by deionized water, and then drying the CC in vacuum at the temperature of 40 ℃ for 24 hours to prepare CoP @ NiCo-LDH/CC;

characterization and electrochemical testing: the structure and the microstructure of the CoP @ NiCo-LDH/CC material are characterized by XRD, SEM, EDX, TEM and XPS, and the overpotential of the water oxidation reaction, the Tafel slope and the cycling stability of the CoP @ NiCo-LDH/CC material are evaluated by using a DH7000 electrochemical workstation.

3. The method of preparing the CoP @ NiCo-LDH/CC water oxidation electrocatalyst as claimed in claim 2, wherein: the electrocatalyst has a three-dimensional core-shell heterogeneous nano array structure, and when the hydrotalcite-based three-dimensional core-shell heterogeneous nano array designed in the way is used as an alkaline water oxidation electrocatalyst, the overpotential of 259 mV is only needed to catalyze 20 mA cm^–2And exhibits outstanding cycle stability performance.