Preparation And Electrocatalytic Performance Of Self-Supporting Substrate Composites

The crisis of fossil energy and the concept of sustainability always urge people to explore new types of clean energy.Hydrogen energy is a typical clean secondary energy,which has been paid more and more attention.Electrocatalytic total hydrolysis of water is one of the most ideal methods for the preparation of hydrogen.In recent years,electrocatalytic hydrogen production has been widely studied,and a series of non-precious metal compound materials with excellent properties have been developed.They show excellent catalytic performance and stability in electrolytic water,but there are still some problems in practical application,such as small load,easy to fall off under high current and so on.For this reason,the researchers found that the introduction of porous substrate and in-situ growth method can not only reduce the use of conductive agent and binder,but also increase the load and active surface area,so as to obtain high-performance three-dimensional hydrogen evolution self-supporting electrode.The research contents of this thesis are as follows:（1）The nanowire array Zn-Co（OH）F was grown on nickel foam（NF）by one-step hydrothermal method as an electrocatalyst（Zn-Co（OH）F/NF）,which showed stable and efficient electrochemical hydrogen evolution performance.Under alkaline condition,Zn-Co（OH）F/NF only needed 136 m V overpotential to reach 10 m A·cm^-2 current density.The superiority of the catalytic performance was mainly attributed to two factors:doping of Zn element and the construction of stable nanowire array structure.In addition,this simple and efficient construction method of self-supporting composites provided a new direction for optimizing the composition of catalysts and improving the performance.（2）Co₂NiN self-supporting electrode（Co₂NiN/CC）was grown on carbon cloth（CC）by hydrothermal and further nitridation.Under the alkaline condition,when the current density was 10 m A·cm^-2 and the HER overpotential was 136 m V;and 40 m A·cm^-2,the OER overpotential was 386 m V.The excellent performance of the material was mainly due to two factors:the unique 3D self-supporting structure not only enhanced the conductivity of the electrode,but also improved the stability of the electrode structure;the super-hydrophilic and aerophobic characteristics of the whole electrode made the contact between the electrolyte and the electrode more sufficient,the charge transfer more convenient,and promoted the bubble release in a certain extent.This preparation method can also be extended to the preparation methods of other flake structures and multi-component composites.（3）Rose-liked Co_0.67Ni_0.33P microflowers(Co_0.67Ni_0.33P/fs-Si)composed of ultra-thin nanowires were prepared on femtosecond laser-treated micro/nanostructured silicon wafers（fs-Si）,which can be used as efficient and stable electrocatalysts for HER in acidic solution.X-ray photoelectron spectroscopy（XPS）showed that there was a charge transfer between CoNiP and fs-Si.Density functional theory（DFT）calculation further proved that fs-Si could adjust the electron density of CoNiP.This interaction was beneficial to improve the HER activity of the electrode.In addition,the overpotentials of the optimized Co_0.67Ni_0.33P/fs-Si catalysts at current densities of 10 and 100 m A·cm^-2 were 67 m V and 165 m V,respectively.This work provided a new idea for the preparation of highly efficient self-supporting electrode for hydrogen production by the combination of physical and chemical methods.