摘要 |
Selective electrocatalytic reduction of carbon dioxide (CO2) to carbon monoxide (CO) on gold (Au) nanoparticles (NPs) in 0.5 M KHCO3 at 25 °C. Among monodisperse 4-, 6-, 8-, and 10-nm NPs tested, the 8 nm Au NPs show the maximum Faradaic efficiency (FE), up to 90% at -0.67 V vs. reversible hydrogen electrode. Density functional theory (DFT) calculations suggest that edge sites dominate over corner sites on the Au NP surface facilitating stabilization of the reduction intermediates, such as COOH*, and the formation of CO. This mechanism is further supported by the fact that Au NPs embedded in a matrix of butyl-3methylimidazolium hexafluorophosphate for more efficient COOH* stabilization exhibit even higher reaction activity (3 A/g mass activity) and selectivity (97% FE) at -0.52 V (vs. RHE). Use of monodisperse Au NPs to optimize the available reaction intermediate binding sites thus allows efficient and selective electrocatalytic reduction of CO2 to CO. |