CdS‐Enhanced Ethanol Selectivity in Electrocatalytic CO<sub>2</sub> Reduction at Sulfide‐Derived Cu−Cd
Venkata Sai Sriram Mosali, Xiaolong Zhang, Yan Liang, Linbo Li, Graeme Puxty, Michael D. Horne, Anna Brajter‐Toth, Alan M. Bond, Jie Zhang
Abstract
Abstract The development of Cu‐based catalysts for the electrochemical CO 2 reduction reaction (eCO 2 RR) is of major interest for generating commercially important C 2 liquid products such as ethanol. Cu is exclusive among the eCO 2 RR metallic catalysts in that it facilitates the formation of a range of highly reduced C 2 products, with a reasonable total faradaic efficiency but poor product selectivity. Here, a series of new sulfide‐derived copper‐cadmium catalysts (SD‐Cu x Cd y ) was developed. An excellent faradaic efficiency of around 32 % but with a relatively low current density of 0.6 mA cm −2 for ethanol was obtained using the SD‐CuCd 2 catalyst at the relatively low overpotential of 0.89 V in a CO 2 ‐saturated aqueous 0.10 m KHCO 3 solution with an H‐cell. The current density increased by an order of magnitude under similar conditions using a flow cell where the mass transport rate for CO 2 was greatly enhanced. Ex situ spectroscopic and microscopic, and voltammetric investigations pointed to the role of abundant phase boundaries between CdS and Cu + /Cu sites in the SD‐CuCd 2 catalyst in enhancing the selectivity and efficiency of ethanol formation at low potentials.