Facet effects on bimetallic ZnSn hydroxide microcrystals for selective electrochemical CO2 reduction

Employing crystal facets to regulate the catalytic properties in electrocatalytic carbon dioxide reduction reaction (eCO 2 RR) has been well demonstrated on electrocatalysts containing single metals but rarely explored for bimetallic systems. Here, we synthesize ZnSn(OH) 6 (ZSO) microcrystals (MCs) with distinct facets and investigate the facet effects in eCO 2 RR. Electrochemical studies and in situ Fourier Transform Infrared Spectroscopy (in situ-FTIR) reveal that ZSO MCs produce mainly C1 products of HCOOH and CO. The {111} facet of the ZSO MCS exhibits higher selectivity and faradaic efficiency (FE) than that of the {100} facet over a wide range of potentials (−0.9 V ∼ −1.3 V versus RHE). Density Functional Theory (DFT) calculations elucidate that the {111} facet is favorable to the adsorption/activation of CO 2 molecules, the formation of intermediate in the rate-determining step, and the desorption of C1 products of CO and HCOOH molecules.