Version 2 2023-12-08, 18:35Version 2 2023-12-08, 18:35
Version 1 2023-12-07, 22:29Version 1 2023-12-07, 22:29
journal contribution
posted on 2023-12-08, 18:35authored byHo Kun Woo, Ankit Kumar Gautam, Jaxiry S. Barroso-Martínez, Arthur P. Baddorf, Kai Zhou, Yoon Young Choi, Jiajun He, Alexander V. Mironenko, Joaquín Rodríguez-López, Lili Cai
Photoelectrochemical (PEC) conversion is a promising
way to use
methane (CH4) as a chemical building block without harsh
conditions. However, the PEC conversion of CH4 to value-added
chemicals remains challenging due to the thermodynamically favorable
overoxidation of CH4. Here, we report WO3 nanotube
(NT) photoelectrocatalysts for PEC CH4 conversion with
high liquid product selectivity through defect engineering. By tuning
the flame reduction treatment, we carefully controlled the oxygen
vacancies of WO3 NTs. The optimally reduced WO3 NTs suppressed overoxidation of CH4 showing a high total
C1 liquid selectivity of 69.4% and a production rate of 0.174 μmol
cm–2 h–1. Scanning electrochemical
microscopy revealed that oxygen vacancies can restrain the production
of hydroxyl radicals, which, in excess, could further oxidize C1 intermediates
to CO2. Additionally, band diagram analysis and computational
studies elucidated that oxygen vacancies thermodynamically suppress
overoxidation. This work introduces a strategy for understanding and
controlling the selectivity of photoelectrocatalysts for direct conversion
of CH4 to liquids.