Journal Article

Electrochemically scrambled nanocrystals are catalytically active for CO 2 -to-multicarbons

Aloni, Shaul, Li, Yifan, Yu, Sunmoon, Kim, Dohyung, Lin, Tom, Kong, Qiao, Xie, Chenlu, Yang, Peidong, Louisia, Sheena, Fakra, Sirine C.

2020

Overview

The electrocatalytic conversion of CO 2 to value-added products, especially valuable multicarbon products, is a pathway toward sustainable formation of chemicals and fuels typically derived from fossil fuels, while mitigating CO 2 emissions. Fundamental understanding and development of more efficient catalysts for this reaction require deep investigation into structures with high intrinsic activity, which are limited at present. This work comprehensively investigates a dynamic copper nanoparticle ensemble catalyst that significantly improves intrinsic activity of copper for multicarbon formation. Through concerted ex situ and in situ characterization techniques, it illustrates an electrochemically induced fusion of copper nanoparticles that result in a catalytically active disordered structure, motivating closer study of disordered metal nanostructures for C–C coupling electrocatalysis. Promotion of C–C bonds is one of the key fundamental questions in the field of CO 2 electroreduction. Much progress has occurred in developing bulk-derived Cu-based electrodes for CO 2 -to-multicarbons (CO 2 -to-C 2+ ), especially in the widely studied class of high-surface-area “oxide-derived” copper. However, fundamental understanding into the structural characteristics responsible for efficient C–C formation is restricted by the intrinsic activity of these catalysts often being comparable to polycrystalline copper foil. By closely probing a Cu nanoparticle (NP) ensemble catalyst active for CO 2 -to-C 2+ , we show that bias-induced rapid fusion or “electrochemical scrambling” of Cu NPs creates disordered structures intrinsically active for low overpotential C 2+ formation, exhibiting around sevenfold enhancement in C 2+ turnover over crystalline Cu. Integrating ex situ, passivated ex situ, and in situ analyses reveals that the scrambled state exhibits several structural signatures: a distinct transition to single-crystal Cu 2 O cubes upon air exposure, low crystallinity upon passivation, and high mobility under bias. These findings suggest that disordered copper structures facilitate C–C bond formation from CO 2 and that electrochemical nanocrystal scrambling is an avenue toward creating such catalysts.

• Publisher: Proceedings of the National Academy of Sciences
• Subject: co2 reduction / electrocatalysis / INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY / nanomaterials / structure dynamics