Size‐Dependent Selectivity of Electrochemical CO2 Reduction on Converted In2O3 Nanocrystals

• Published in: Angewandte Chemie International Edition 2021-07, Vol.60 (29), p.15844-15848
• Main Authors: Huang, Yang, Mao, Xinnan, Yuan, Guotao, Zhang, Duo, Pan, Binbin, Deng, Jun, Shi, Yunru, Han, Na, Li, Chaoran, Zhang, Liang, Wang, Lu, He, Lin, Li, Youyong, Li, Yanguang
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Catalysts; Crystals; Cubes; electrochemical CO2 reduction; Electrochemistry; Foils; formate; Indium; indium oxide nanocrystals; Indium oxides; Nanocrystals; Nanoparticles; Particle size distribution; Reduction; Selectivity; Side reactions; size dependence; Size distribution
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202105256

The size modulation of catalyst particles represents a useful dimension to tune catalytic performances by impacting not only their surface areas but also local electronic structures. It, however, has remained inadequately explored and poorly elucidated. Here, we report the interesting size‐dependent selectivity of electrochemical CO2 reduction on In2O3 nanocrystals. 5‐nm nanoparticles and 15‐nm nanocubes with focused size distribution are prepared via a facile solvothermal reaction in oleylamine by carefully controlling a set of experimental parameters. They serve as the precatalysts, and are reduced to In nanocrystals while largely inherit the original size feature during electrochemical CO2 reduction. Catalyst derived from 15‐nm nanocubes exhibits greater formate selectivity (>95 %) at lower overpotential and negligible side reactions compared to bulk‐like samples (indium foil and 200‐nm cubes) as well as the catalyst derived from smaller 5‐nm nanoparticles. This unique size dependence is rationalized as a result of the competition among different reaction pathways by our theoretical computations. Smaller is not always better in the catalyst design. 15‐nm In2O3 nanocubes as the precatalyst are observed to exhibit greater CO2 reduction selectivity towards formate than bulk‐like samples as well as smaller nanoparticles. This unique size dependence is rationalized as a result of the competition among different reaction pathways, suggesting that smaller is not always better in the catalyst design.