Defect Engineering of WO<sub>3</sub> by Rapid Flame Reduction for Efficient Photoelectrochemical Conversion of Methane into Liquid Oxygenates.
basic_science · Level V
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- Record sourced from PubMed, PMID 38061056.
- Also identified by DOI 10.1021/acs.nanolett.3c03131.
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Abstract
Photoelectrochemical (PEC) conversion is a promising way to use methane (CH<sub>4</sub>) as a chemical building block without harsh conditions. However, the PEC conversion of CH<sub>4</sub> to value-added chemicals remains challenging due to the thermodynamically favorable overoxidation of CH<sub>4</sub>. Here, we report WO<sub>3</sub> nanotube (NT) photoelectrocatalysts for PEC CH<sub>4</sub> conversion with high liquid product selectivity through defect engineering. By tuning the flame reduction treatment, we carefully controlled the oxygen vacancies of WO<sub>3</sub> NTs. The optimally reduced WO<sub>3</sub> NTs suppressed overoxidation of CH<sub>4</sub> showing a high total C1 liquid selectivity of 69.4% and a production rate of 0.174 μmol cm<sup>-2</sup> h<sup>-1</sup>. Scanning electrochemical microscopy revealed that oxygen vacancies can restrain the production of hydroxyl radicals, which, in excess, could further oxidize C1 intermediates to CO<sub>2</sub>. 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 CH<sub>4</sub> to liquids.