%0 Journal Article
%T On the Role of Sulfur for the Selective Electrochemical Reduction of CO2 to Formate on CuSx Catalysts
%J -
%D 2018
%R https://doi.org/10.1021/acsami.8b08428
%X The efficient electroreduction of CO2 has received significant attention as it is one of the crucial means to develop a closed-loop anthropogenic carbon cycle. Here, we describe the mechanistic workings of an electrochemically deposited CuSx catalyst that can reduce CO2 to formate with a Faradaic efficiency (FEHCOO¨C) of 75% and geometric current density (jHCOO¨C) of £¿9.0 mA/cm2 at £¿0.9 V versus the reversible hydrogen electrode. At this potential, the formation of other CO2 reduction products such as hydrocarbons and CO was notably suppressed (total FE < 4%). The formate intermediate (HCOO*) was identified by operando Raman spectroscopy with isotopic labeling. A combination of electrochemical and materials characterization techniques revealed that the high selectivity toward formate production can be attributed to the effect of S dopants on the Cu catalyst, rather than surface morphology. Density functional theory calculations showed that the presence of sulfur weakens the HCOO* and *COOH adsorption energies, such that the formation of *COOH toward CO is suppressed, while the formation of HCOO* toward formate is favored
%U https://pubs.acs.org/doi/10.1021/acsami.8b08428