Preparation And Their Electrocatalytic Hydrogen Evolution Of COFs/Transition Metal Composites Catalysts

Electrochemical water splitting is a desired method to generate high purity hydrogen.At present,it is very important to develop a non-noble metal catalyst which is cost-effective and durable.Among the catalysts for electrocatalytic hydrogen evolution,transition metal-based materials have attracted the attention of researchers due to their unique structural properties and extensive distribution of earth resources.However,the bulk transition metal materials have a wide band gap,poor electrical conductivity,easy accumulation and agglomeration,which lead to cover active sites and affect catalytic activity.Nano-scale transition metal catalysts can avoid the above problems,but they need a conductive support usually.Covalent organic frameworks（COFs）,with large specific surface area,regular one-dimensional channels,inherent active sites and favorable stability,can be efficient carrier for transition metal catalysts.The research contents are mainly divided into the following two aspects:（1）We used a one-step hydrothermal method to restrict the growth of molybdenum disulfide on the inner and outer surfaces of the channels of the COFs through a spatially confined strategy.So,the in-situ growth of molybdenum disulfide could avoid accumulation effectively and expose more sulfur edges,improving the electrocatalytic activity.The experiment result shows that the state-of-the-art CTFs@Mo S₂-5 structure exhibits superior catalytic kinetics with an overpotential of 93 mV and Tafel slope of 43mVdec^-1,which is improved over most other reported analogous catalysts.（2）We used a coordination strategy by designing coordination sites on the surface of covalent organic framework,and the coordination groups serve as"claws"to capture and anchor the mononuclear metal precursor（Ni,Co）.Then,the coordination compound formed by the strong interaction between the metal and the coordination site is used to prevent its migration and agglomeration,resulting in exposing more active sites and improving the electrocatalytic activity.The experiment result shows that DCP-CTF-Co²⁺demonstrats high electrocatalytic activity with an overpotential of 119 mV and Tafel slope of 44.3 mVdec^-1.