Engineering facet-dependent interface charge transfer in liquid metal-embraced BiVO${}_4$ photoelectrodes for efficient photoelectrochemical water splitting

Crystal facet-dependent photogenerated charge transfer at the semiconductor/current collector interface of photoelectrodes is equally important compared to that at the semiconductor/liquid interface for efficient photoelectrochemical (PEC) water splitting, which, however, is difficult to explore due to the rigid solid/solid interface in conventional photoelectrodes. Here, the facet-dependent charge transfer at both semiconductor/liquid and semiconductor/collector interfaces in liquid metal-embraced photoelectrodes is systematically investigated using faceted BiVO${}_4$ micro-particles with different ratios of {110} and {010} facets as model materials. The results from the photo(electro)chemical and photophysical characterizations reveal that {010} facets outperform {110} facets at the semiconductor/liquid interface in triggering water oxidation due to the lower valence band maximum (VBM) of {010} facets, while {110} facets are more efficient at the semiconductor/metal interface for the collection of photogenerated electrons due to their higher conduction band minimum (CBM). Consequently, the photoelectrodes of liquid metal-embraced BiVO${}_4$ particles exposing 53% {110} facets yield the best PEC performance for water splitting due to the well-balanced photogenerated charge transfer at the interfaces of semiconductor/metal and semiconductor/liquid. (© 2024 Wiley‐VCH GmbH)