Bromine‐Enhanced Generation and Epoxidation of Ethylene in Tandem CO<sub>2</sub> Electrolysis Towards Ethylene Oxide
Wenjie Xue, Quan Li, Hongxia Liu, Bo Yu, Xinqing Chen, Bao Yu Xia, Bo You
Abstract
Abstract The indirect electro‐epoxidation of ethylene (C 2 H 4 ), produced from CO 2 electroreduction (CO 2 R), holds immense promise for CO 2 upcycling to valuable ethylene oxide (EO). However, this process currently has a mediocre Faradaic efficiency (FE) due to sluggish formation and rapid dissociation of active species, as well as reductive deactivation of Cu‐based electrocatalysts during the conversion of C 2 H 4 to EO and CO 2 to C 2 H 4 , respectively. Herein, we report a bromine‐induced dual‐enhancement strategy designed to concurrently promote both C 2 H 4 ‐to‐EO and CO 2 ‐to‐C 2 H 4 conversions, thereby improving EO generation, using single‐atom Pt on N‐doped CNTs (Pt 1 /NCNT) and Br − ‐bearing porous Cu 2 O as anode and cathode electrocatalysts, respectively. Physicochemical characterizations including synchrotron X‐ray absorption, operando infrared spectroscopy, and quasi in situ Raman spectroscopy/electron paramagnetic resonance with theoretical calculations reveal that the favorable Br 2 /HBrO generation over Pt 1 /NCNT with optimal intermediate binding facilitates C 2 H 4 ‐to‐EO conversion with a high FE of 92.2 %, and concomitantly, the Br − with strong nucleophilicity protects active Cu + species in Cu 2 O effectively for improved CO 2 ‐to‐C 2 H 4 conversion with a FE of 66.9 % at 800 mA cm −2 , superior to those in the traditional chloride‐mediated case. Consequently, a single‐pass FE as high as 41.1 % for CO 2 ‐to‐EO conversion can be achieved in a tandem system.