Unusual facet and co-catalyst effects in TiO<sub>2</sub>-based photocatalytic coupling of methane.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38789454.
- Also identified by DOI 10.1038/s41467-024-48866-1 and PMC identifier 11126583.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Photocatalytic coupling of methane to ethane and ethylene (C<sub>2</sub> compounds) offers a promising approach to utilizing the abundant methane resource. However, the state-of-the-art photocatalysts usually suffer from very limited C<sub>2</sub> formation rates. Here, we report our discovery that the anatase TiO<sub>2</sub> nanocrystals mainly exposing {101} facets, which are generally considered less active in photocatalysis, demonstrate surprisingly better performances than those exposing the high-energy {001} facet. The palladium co-catalyst plays a pivotal role and the Pd<sup>2+</sup> site on co-catalyst accounts for the selective C<sub>2</sub> formation. We unveil that the anatase {101} facet favors the formation of hydroxyl radicals in aqueous phase near the surface, where they activate methane molecules into methyl radicals, and the Pd<sup>2+</sup> site participates in facilitating the adsorption and coupling of methyl radicals. This work provides a strategy to design efficient nanocatalysts for selective photocatalytic methane coupling by reaction-space separation to optimize heterogeneous-homogeneous reactions at solid-liquid interfaces.