Investigation On Preparation And Performance Of Transition Metal Based Electrocatalysts For Water Splitting

Hydrogen possesses high-energy density and renewability,which shows promising practicability.Electrocatalytic water splitting is a feasible and convenient strategy for hydrogen production.However,the sluggish kinetics of oxygen evolution reaction（OER）at anode can impede the hydrogen evolution reaction（HER）process,and noble-metal-based electrocatalysts increase the production costs.Recently,due to appropriate catalytic activity,cheap transition-metal-based catalysts have aroused wide attention.Furthermore,in order to obtain highly reactive,stable and cost-effective HER/OER electrocatalysts,we will improve transition-metal-based catalysts via elemental doping,interface modification and defect control.In conclusion,the research contents are as follows:（1）The Ni₂P nanosheets arrays modified with ruthenium nanoparticles were grown in situ on a carbon cloth substrate to synthesize Ru-Ni₂P/CC electrode.The favorable conductivity and superior hydrophilicity of Ru-Ni₂P/CC were conducive to the charge transportation and the rapid release of gases.The resulting Ru-Ni₂P/CC-5 only required an ultra-low overpotential of 23 m V to achieve a current density of 10 m A cm^-2 for HER in 1M KOH solution.The X-ray photoelectron spectroscopy（XPS）characterization showed that the Ru will lead to the strong electron interactions within Ni₂P.The density functional theory（DFT）calculations further revealed that Ni₂P modified with Ru can promote the dissociation of water molecules,which was favorable to optimize the HER process on Ru sites.The cost-effective doping strategy can effectively enhance the HER catalytic activity of Ni₂P and offer a reasonable design routine for industrial electrocatalysts.（2）The zeolite imidazole framework embedded with iron atoms was converted to Fe-N-C single atom catalysts via high temperature pyrolysis.The synthesized Fe₉₀-N-C/NF exhibited an low overpotential of 172 m V to achieve a current density of 100 m A cm^-2 for OER.The corresponding characterization showed that the highly electronegative N atoms coordinate with Fe atoms to result in moderate electron interactions,which was beneficial to the optimization of adsorption and desorption of intermediates during water splitting.In addition,the enhancement of defect states of Fe₉₀-N-C/NF promoted the exposure of active sites,which further improved the OER catalytic activity.The excellent electrolysis stability at high current density was related to the strong coordination of Fe-N bond.Hence,the high atomic utilization efficiency and good coordination environment both improved the OER catalytic activity and electrolysis stability of Fe₉₀-N-C/NF,exhibiting wide industrial application prospect.