Ligand-Controlled Electroreduction of CO₂ to Formate over Facet-Defined Bimetallic Sulfide Nanoplates

CO2 reduction (CO2R) catalyzedby an efficient,stable, and earth-abundant electrocatalyst offers an attractive meansto store energy derived from renewable sources. Here, we describethe synthesis of facet-defined Cu2SnS3 nanoplatesand the ligand-controlled CO2R property. We show that thiocyanate-cappedCu(2)SnS(3) nanoplates possess excellent selectivitytoward formate over a wide range of potentials and current densities,attaining a maximum formate Faradaic efficiency of 92% and partialcurrent densities as high as 181 mA cm(-2) when testedusing a flow cell with gas-diffusion electrode. In situ spectroscopicmeasurements and theoretical calculations reveal that the high formateselectivity originates from favorable adsorption of HCOO* intermediateson cationic Sn sites that are electronically modulated by thiocyanatesbound to adjacent Cu sites. Our work illustrates that well-definedmultimetallic sulfide nanocrystals with tailored surface chemistriescould provide a new avenue for future CO2R electrocatalystdesign.