Cubic In₂O₃ microparticles with exposed {001} facets as well as single morphology and size are produced on a large scale on silicon with a high yield. The morphological evolution during chemical vapor deposition is investigated and the new knowledge enables precise facet cutting. The synthesized Cubic In₂O₃ microparticles possess superior photoelectrocatalytic activity and excellent chemical and structural stability in oxygen evolution reaction on account of the unique surface structure and electronic band structure of the {001} facets. Our results reveal that it is feasible to promote the photolectrochemical water splitting efficiency of photoanode materials by controlling the growth on specific crystal facets. The technique and concept can be extended to other facet-specific materials in applications such as sensors, solar cells, and lithium batteries.

This review offers an overview of the design principles, progress, and perspectives of applying multi-site electrocatalysts for the HER in neutral media.