Iodide Ion And Pyrenyl-graphdiyne On Bismuth Subcarbonate Nanosheets For Highly Efficient Electrocatalytic Carbon Dioxide Reduction

Electrocatalytic carbon dioxide（CO₂）reduction technology can convert CO₂ into value-added carbon fuels or chemicals driven by electric energy,which is an effective way to solve the energy crisis.However,it is necessary to develop electrocatalysts with high product selectivity under a wide potential window.Under near-neutral or alkaline conditions,the accumulation of carbonate reduces the utilization efficiency of CO₂ and the stability of electrocatalyst.Electrocatalytic reduction of CO₂ in acidic electrolytes can effectively solve these problems.Bismuth subcarbonate nanosheets（PGDY@I-BOC）modified with iodide ion and pyrenyl-graphdiyne have been prepared and used for electrocatalytic CO₂ reduction.The faraday efficiency of formate and the stability of catalyst are significantly improved.The details described as follows:1.I-BOC nanosheets were synthesized by using bismuth nitrate pentahydrate（Bi（NO₃）₃·5H₂O）and potassium iodide（KI）as the main raw materials.The electrochemical test shows that I-BOC nanosheets exhibit excellent performance for electrocatalytic CO₂ reduction in H-cell under near neutral conditions.The FEs of formate all exceed 90.0%within the potential range from-0.9 to-1.3 V vs.RHE.In addition,I-BOC nanosheets exhibit high stability at-1.1 V vs.RHE with negligible change in current density in 68 h.Under acidic conditions,a high faradic efficiency of91.49%for formate is achieved at-1.4 V vs.RHE.Through In situ Raman spectroscopy,X-ray diffraction and X-ray photoelectron spectroscopy,it can be conformed that iodide modified bismuth is used as the active site for CO₂ reduction.Compared with perfect bismuth site,it is found that iodide modified bismuth site has lower formate formation free energy for electrocatalytic CO₂ reduction reaction.2.Based on I-BOC nanosheets,PGDY@I-BOC nanosheets were prepared and used for efficient electrocatalytic CO₂ reduction.In H-cell,the Faraday efficiency of formate is above 90.0%in the potential window of more than 600 m V under near-neutral conditions.Under acidic conditions,the maximum partial current density of formate is 98.71 m A cm^-2 at-1.7 V vs.RHE.The stability of the PGDY@I-BOC nanosheets are also examined at-1.4 V vs.RHE for 230 h.The EIS spectra and tafel plots show that PGDY@I-BOC nanosheets have stronger charge transfer ability and faster reaction kinetics.The CO₂ adsorption and electrochemical active surface area further indicate that PGDY@I-BOC nanosheets have stronger CO₂ adsorption capacity and more active sites.In conclusion,Bismuth subcarbonate nanosheets modified with iodide and pyrenyl-graphdiyne show better performance for electrocatalytic CO₂ reduction reaction.