Study On Surface Physical Properties And Carbon Dioxide Electroreduction Of Silver And Copper Nanomaterials

Electrochemical reduction of carbon dioxide（CO₂RR）can convert CO₂ into value-added hydrocarbon fuels.The development of catalysts with high activity and selectivity is an important way to promote the effective recycling of CO₂.However,the low activity and poor selectivity of catalysts greatly limit the utilization of CO₂ resource.Silver and copper nanomaterials with excellent surface physical properties exhibit high catalytic activity.In this work,the reaction mechanism of Ag/Sn and P-Cu nanomaterials in CO₂RR was investigated.It was found that the catalytic activity and selectivity of Ag and Cu nanomaterials was improved by the effect of local electric field enhancement and"spatial confinement",respectively.The main research works are shown as follows:（1）To investigate effect of local electric field on catalytic performance of Ag/Sn nanomaterials,Ag/Sn nanomaterial was prepared by simple coprecipitation reduction method.The theoretical calculation and simulation results demonstrate that heteroatom induces the enhanced local electric field,local electric field lower energy barrier of*COOH in CO₂RR reaction.The differential phase contrast-scanning transmission electron microscopy（DPC-STEM）revealed that there is a strong local electric field on Ag/Sn nanomaterials.In-situ attenuated total reflection infrared spectroscopy（ATR-IR）results indicate that the localized electric field enhances the adsorption of intermediate*COOH.Hence,the catalyst exhibits a～100%faradaic efficiency under the grand potentials（-0.5 to-1.1 V vs RHE）in CO₂RR.（2）To explore the effect of“spatial confinement”on catalytic activity,P-Cu nanomaterial was synthesized by liquid phase reduction method.COMSOL simulation results confirm that there is a strong local electric field,thus leading to the effect of“spatial confinement”.The CO gas sensor and temperature programmed desorption（TPD）tests prove that the P-Cu exhibits a great CO adsorption and enrichment capacity,which proves that the“spatial confinement”enhances the adsorption of*CO,thus improving the C-C coupling efficiency.As a result,P-Cu exhibits a high C2 selectivity with a Faradaic efficiency of 57.22%in CO₂RR,it is about 2.5-fold that of compact Cu nanomaterial.There are 25 figures,6 tables and 132 references...