Engineering Facet‐Dependent Interface Charge Transfer in Liquid Metal‐Embraced BiVO₄ Photoelectrodes for Efficient Photoelectrochemical Water Splitting

Abstract 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 BiVO₄ 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 BiVO₄ 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.