Facet Engineering on WO 3 Mono-Particle-Layer Electrode for Photoelectrochemical Water Splitting.

Photoelectrochemical (PEC) performance of WO 3 photoanodes for water splitting is heavily influenced by the orientation of crystal facets. In this work, mono-particle-layer electrodes, assembled by particulate WO 3 square plates with highly uniform alignment along the (002) facet, improved PEC water oxidation kinetics and stability. Photo-deposition of Au along the cracks formed on the surface of the plates, which are the edges of {110} facets, was found to further enhance electron collection efficiency. Combination of these two strategies allowed the facet-engineered WO 3 electrode to produce significantly higher efficiencies in charge separation and transfer than the electrode prepared without facet orientation. This work has provided a facile route for fabricating a structurally designed WO 3 photoelectrode, which is also applicable to other regularly shaped semiconductor photocatalysts with anisotropic charge migration.