Oxygen vacancies in amorphous InO${}_x$ nanoribbons enhance CO${}_2$ adsorption and activation for CO${}_2$ electroreduction

Tuning surface electron transfer process by oxygen (O)-vacancy engineering is an efficient strategy to develop enhanced catalysts for CO${}_2$ electroreduction (CO${}_2$ER). Herein, a series of distinct InO${}_x$ NRs with different numbers of O-vacancies, namely, pristine (P-InO${}_x$), low vacancy (O-InO${}_x$) and high-vacancy (H-InO${}_x$) NRs, have been prepared by simple thermal treatments. The H-InO${}_x$ NRs show enhanced performance with a best formic acid (HCOOH) selectivity of up to 91.7 % as well as high HCOOH partial current density over a wide range of potentials, largely outperforming those of the P-InO${}_x$ and O-InO${}_x$ NRs. The H-InO${}_x$ NRs are more durable and have a limited activity decay after continuous operating for more than 20 h. The improved performance is attributable to the abundant O-vacancies in the amorphous H-InO${}_x$ NRs, which optimizes CO${}_2$ adsorption/activation and facilitates electron transfer for efficient CO${}_2$ER. (© 2019 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)