Preparation Of Silver Nanocatalyst On Carbon And Its Electrochemical Reduction Of CO₂

With the rapid development of the economy,the traditional fossil energy consumes continuously and the carbon dioxide is accumulated in the atmosphere,which causes serious energy security and environmental protection problems and threatens the sustainable development of human society.Therefore,there is an urgent need for an effective method to accelerate the fixation and conversion of CO₂.Electrocatalytic CO₂reduction has great potential to deal with energy and environmental crises by converting excess CO₂ into high-value chemicals and fuels,showing great application potential.Nowadays,the research focus on electrochemical CO₂ reduction is mainly focused on the development and utilization of efficient catalysts.Silver(Ag)based materials are widely used in CO₂ electrocatalytic reduction due to their high Faradaic efficiency of CO.This paper analyzes and designs the Ag material to make it an excellent electrocatalytic CO₂ reduction catalyst by further decreasing its overpotential and improving its reaction stability.The main research contents are as follows:Firstly,thin Ag polycrystalline film was synthesized on carbon papers by a simple vacuum evaporation method.After 15 min-O₃ treatment under ambient temperature,the Ag electrocatalysts can produce CO with a Faradaic efficiency up to 93.3%at-0.9 V versus reversible hydrogen electrode(vs.RHE),which is obviously higher than that of pure polycrystalline Ag.In addition,the Ag electrode retained?90%catalytic selectivity for CO after a 10-hour test.The characterizations show that the surface Ag_xO layer on Ag was reduced to Ag~0,which not only reduces the activation energy barrier of the initial electron transfer but also provides an increased number of active sites for the reduction of CO₂ to CO.In order to further reduce the overpotential of Ag-based catalyst,this work synthesized Ag nanoparticles on nitrogen-doped porous carbon(NC),by pre-carbonating and high-temperature annealing method using silicon spheres(50 nm)as a template.The Ag-based catalyst couples nitrogen-doped carbon sites and nano-silver particles,which enables it to achieve a CO the Faradaic efficiency of 94%at a lower overpotential of-0.7 V vs RHE through the synergistic effect.Theoretical calculation proves that the Ag atom regulated nitrogen-doped carbon site is a good reaction center for electrocatalytic reduction of CO₂.In addition,after 12 hours of testing,Ag/NC maintained more than 90%of its catalytic activity,proving its good stability.