State-of-the-art advancements of crystal facet-exposed photocatalysts beyond TiO2: Design and dependent performance for solar energy conversion and environment applications

Tailoring semiconductor crystals with optimized reactive facets is considered one of effective strategies to improve photocatalytic activity and selectivity for energy conversion and environmental remediation. The arrangement of surface atom structure through crystal facet engineering could tune surface free energy, electronic band structure, charge transfer and separation, the reactant adsorption and product desorption, and surface redox sites. This progress report aims to concisely highlight recent state-of-the-art progress of crystal facet-dependent performance of promising photocatalysts beyond TiO2. It includes (1) design of crystal-facet exposed photocatalysts with various routes through altering the relative order of the surface energy; (2) crystal facet-based surface junctions to promote the charge transfer and separation; (3) in situ techniques to detection of charge accumulation on crystal-faceted surfaces; (4) exposed face-determined photocatalytic application in water splitting, photoreduction of CO2 into renewable fuels, degradation of organic contaminants from the point of the reactant adsorption and activation. The challenges and prospects for future development are also presented.