镍基金属有机框架衍生的双功能电催化剂用于析氢和析氧反应

Nickel-Based Metal-Organic Framework-Derived Bifunctional Electrocatalysts for Hydrogen and Oxygen Evolution Reactions

开发高活性、低成本的析氢反应和析氧反应电催化剂对于能源的可持续发展至关重要。金属有机框架衍生的纳米材料已经成为一类非常有前景的非贵金属双功能电催化剂,但是目前对镍基金属有机框架衍生的双功能电催化剂的深入研究并不全面,其催化活性和稳定性还有待进一步提高。本文制备了一种棒状多孔碳负载镍纳米颗粒的新型电催化剂,并将其用作电催化析氢和析氧反应。实验研究结果表明该类电催化剂表现出优异的析氢和析氧反应活性和长期稳定性,在10 mA·cm^(-2)的电流密度下,析氢反应和析氧反应的过电位分别为120和350 mV。我们认为:材料可控的纳米结构和均匀分布的活性位点共同提升了复合材料的电催化性能。

In recent years,electrochemical water splitting that involves the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)has attracted widespread attention because the process is clean,environmentally friendly,and the generated oxygen/hydrogen gas can be converted into electricity in a fuel cell.However,the HER and OER kinetics are sluggish and require highly efficient electrocatalysts for enhancing the reaction rate.Currently,precious metals such as Pt and RuO_(2) have shown excellent HER and OER performance,respectively,but their practical applications are limited by their scarcity and high price.Therefore,the use of 3d transition metals,such as iron(Fe)and nickel(Ni),as electrocatalysts has attracted significant attention.To obtain a catalytic performance similar to that of precious metals,several methods have been explored,such as alloying 3d transition metals with precious metals,compositing a variety of transition metals,or requiring good carbon-based materials as a supporter.Metal-organic framework(MOF)-derived nanomaterials have emerged as some of the most promising non-precious metal bifunctional electrocatalysts.The MOF structure consists of metal-based units and special organic ligands,and after annealing,metal atoms can be converted into unsaturated metal-based active sites,and the organic ligands can be converted into carbon support.This could accelerate the charge transfer efficiency and can be beneficial for achieving excellent HER and OER performance.However,bifunctional electrocatalysts derived from nickel(Ni)-based MOFs have not been studied intensively,and their catalytic activity and stability remain to be improved.Herein,a Ni-MOF precursor was synthesized via a liquid-phase coordination reaction using Ni^(2+) and benzene-1,3,5-tricarboxylic acid.The obtained NiMOF samples were annealed under H_(2)/Ar atmosphere at 600,700,and 800℃,named Ni/C-H_(2)-600,Ni/C-H_(2)-700,Ni/CAr-700,and Ni/C-H_(2)-800,respectively.During high-temperature annealing treatment,Ni nanoparticles were grown in situ on a rod-shaped carbon substrate to form novel hybrid architecture Ni/C nanoparticles used as a high-performance bifunctional electrocatalyst for overall water splitting.The HER overpotential of Ni/C-H_(2)-700 was 120 m V at a current density of 10 m A·cm^(-2),which is much lower than that of Ni/C-H_(2)-600(250 m V),Ni/C-H_(2)-800(348 m V),and Ni/C-Ar-700(275 m V).Ni/C-H_(2)-700 required an OER overpotential of 350 m V to achieve a current density of 10 m A·cm^(-2),which is lower than that of Ni/C-H_(2)-600(370 m V),Ni/C-H_(2)-800(430 m V),and Ni/C-Ar-700(380 m V).Furthermore,Ni/C-H_(2)-700 showed the idea of HER and OER durability.Presumably,good structural properties and the abundant surface area of the carbon substrate elevated HER/OER activity owing to the synergistic advantages of accessible active sites and enhanced electronic conductivity.