Unraveling Side Reactions in Paired CO 2 Electrolysis at Operando Conditions: A Case Study of Ethylene Glycol Oxidation

作者：Xiaoyi Jiang, Kai Zhao, Haozhou Feng, Le Ke, Xiude Wang, Yu‐Chen Liu, Lingjiao Li, Pengfei Sun, Zhou Chen, Yifei Sun, Zhiping Wang, Lin Yu, Ning Yan · 发表于：Journal of the American Chemical Society · 年份：2025 · DOI：10.1021/jacs.5c00325 · 被引用次数：54 · 研究领域：CO2 Reduction Techniques and Catalysts、Ionic liquids properties and applications、Catalysis and Oxidation Reactions

Replacing the oxygen evolution reaction (OER) in CO 2 electrolysis with an energetically and economically favorable alternative is very promising. Yet, understanding paired organic oxidation in the environment for CO 2 reduction is particularly challenging, as monitoring multiple side reactions is problematic. Herein, we examined the oxidation of ethylene glycol (EG), one of the simplest polyols, as a model reaction on a series of nickel oxyhydroxide model catalysts (β-NiM x OOH, M = Ni, Co, Fe, and Cu). Using in situ techniques, including surface-enhanced infrared absorption spectroscopy (SEIRAS) and differential electrochemical mass spectrometry (DEMS), together with various ex situ approaches, we obtained the potential-resolved and quantitative information on various side reactions comprising the OER, overoxidation to CO/CO 2, catalyst dissolution, and CO 2 evolution from electrolyte decarbonation. Many factors including impurity cations, pH, and potential can substantially influence the product distribution and side reactions. Such influences are nearly identical for both the electrocatalytic and chemical–electrochemical oxidation pathways. The optimized system can achieve stable and high Faradaic efficiencies of formate (∼100%), glycolaldehyde (∼86%), and glycolate (∼66%), respectively. Importantly, paired electrolysis can easily suffer from higher energy consumption than the conventional counterpart, provided side reactions are unregulated. Yet the modulated one consume...