Regulating the Oxophilicity of Cu Sites on Cu–Sn Heterostructures to Ultrahigh Selective Electroreduction of CO <sub>2</sub> to Ethanol
Jiahui Bi, Yiyuan Xu, Yunxiu Zhao, Jing Zhang, Changle Yue, Fengyue Sun, Na Liu, Fan Wang, Yanwei Ju, Chongzheng Xu, Yukun Lu
Abstract
The electrochemical CO 2 reduction reaction (CO 2 RR) to ethanol offers a great promise route for carbon utilization, yet achieving high selectivity remains challenging due to complex intermediates. Here, chitosan-supported CuSn bimetallic catalytic electrodes (CuSn- x ) were prepared via a controlled electrodeposition time ( x ) to steer reaction pathways. The optimized CuSn-15s electrode featured ultrasmall nanoparticles (2.7 ± 0.1 nm) with Cu(111)/Sn(220) heterostructures and a C 2 H 5 OH Faradaic efficiency (FE) of 74.3% at a current density of 100 mA·cm –2 with an applied potential of −1.00 V vs RHE. Its FE(ethanol)/FE(ethylene) surpassed that of the Sn-free Cu NPs-CS electrode by 14.6-fold. In situ studies and DFT results revealed that Sn enhanced the oxophilicity around Cu sites, strengthening oxygenated species adsorption, while the Cu(111)/Sn(220) interface directed intermediates toward ethanol via dual mechanisms: (1) elevating *CO coverage for asymmetric C–C coupling (*OCCOH) and (2) stabilizing CH 2 CHO* hydrogenation into *OC 2 H 5 . This work demonstrated that regulating the oxophilicity of active sites through heterostructure engineering can selectively control cascade reactions, providing a blueprint for designing efficient CO 2 -to-ethanol catalytic electrodes.