Paired Electrosynthesis of H<sub>2</sub> and Acetic Acid at A/cm<sup>2</sup> Current Densities
Cong Tian, Xiaoyan Li, Vivian E. Nelson, Pengfei Ou, Daojin Zhou, Yuanjun Chen, Jinqiang Zhang, Jianan Erick Huang, Ning Wang, Jiaqi Yu, Hengzhou Liu, Cheng Liu, Yi Yang, Tao Peng, Yong Zhao, Byoung‐Hoon Lee, Sasa Wang, Erfan Shirzadi, Zhu Chen, Rui Kai Miao, David Sinton, Edward H. Sargent
Abstract
Industrial water splitting pairs cathodic hydrogen evolution with oxygen evolution at the anode, the latter generating low-value oxygen as the oxidative product. We reasoned that replacing the oxygen evolution reaction (OER) with anodic electrosynthesis of acetic acid from ethanol at industrial current densities could be a route to increase the economic efficiency of green hydrogen production. We partition the selective oxidation of ethanol to acetic acid into two mechanistically distinct transformations: first ethanol oxidation followed by the production of *OH. Density functional theory (DFT) studies show that the aldehyde-derived intermediate CH 3 CO* from ethanol oxidation and the *OH radical from water dissociation are both needed in the electroproduction of acetic acid. Operando Fourier transform infrared (FTIR) spectroscopy identifies the corresponding aldehyde intermediates on the anode surface. Based on these mechanistic findings, we develop a vacancy-rich IrRuO x catalyst and achieve selective electrotransformation of ethanol to acetic acid at a generation rate of 30 mmol/cm 2 /h and a partial current density of 3 A/cm 2, fully 10× higher than in the previous highest-activity reports.