Application And Research Of Metal-based Catalysts In Electrocatalytic Reduction Of Carbon Dioxide

Carbon dioxide produced in the natural environment is one of the resources necessary for the growth of plants and the survival and development of other organisms.In an ideal world,carbon dioxide production and consumption should be balanced so that nature is healthy and safe.However,over the past century,the accelerated consumption of fossil fuels has led to excessive emissions and accumulation of carbon dioxide,and this uncontrolled release of carbon dioxide into the atmosphere has sparked serious debate about social sustainability and environmental consequences.Electrocatalytic CO₂ reduction technology uses low order renewable green electricity to reduce CO₂ to high value-added chemicals or fuels,such as CO,formic acid,ethanol,methane,ethane,etc.,which provides raw materials for the production of chemical products while alleviating environmental pressure.This paper mainly studies the materials of related non-noble metals nickel and copper and their application in electrochemical reduction of CO₂.Herein,we report novel electrocatalysts in which Ni nanoparticles encapsulated in N-rich carbon nanotubes（Ni@NCNT）by facile chemical vapor deposition method.The optimized Ni@NCNT-700 exhibits a high ethanol FE of 38.5%at-0.5 V vs.RHE and remains over 30%in a wide potential range of-0.5～-1.2 V vs.RHE.Notably,ethanol is the only liquid product and the total FE for the reduction products CO and ethanol keeps above 90%in a potential range of-0.6～-1.2 V vs.RHE.A high current density of 128 m A cm^-2 is obtained in a 1 M KOH electrolyte at-2.0 V in a flow-cell device.In-situ Raman spectra identify the key intermediates in the CO₂-to-ethanol conversion.Moreover,density functional theory（DFT）calculations demonstrate that the confinement and synergistic effects of Ni-NPs and NCNTs sufficiently lower the energy barrier for C-C coupling and depress the*CO desorption.Meanwhlie,we also reported that a second metal doped Cu₂O catalyst（Sn/Cu₂O）was synthesized by solvothermal method,which is simple and easy to operate.Due to the doping and regulation of the second metal,the catalytic activity and product selectivity of the catalyst were greatly improved.The Faraday efficiency of formic acid is up to 79.6%at the voltage of-0.7V vs.RHE,and above 70%at the voltage range of-0.6V～-1.1V vs.RHE.