Facet Junction Engineering for Photocatalysis: A Comprehensive Review on Elementary Knowledge, Facet-Synergistic Mechanisms, Functional Modifications, and Future Perspectives

A facet junction (also called facet heterojunction or surface heterojunction) is defined as a complex polyhedral single crystal exposed to two, three, or four types of crystallographic planes, and is a promising platform for achieving multifunctional photocatalysis. Compared with simple polyhedral counterparts enclosed by the same crystallographic planes or conventional heterogeneous junctions, facet junctions have notable facet-crosslinking effects arising from different electronic structures of heterogeneous facets, which is beneficial for promoting the transfer and separation of photogenerated charge carriers in a single-crystalline semiconductor without the introduction of external species or interfaces. However, there are few specialized review articles on facet junction engineering of photocatalysts. Herein, an overview of facet junction-based photocatalysts is provided based on the following aspects: elementary knowledge, microstructural features, intrinsic facet-synergistic mechanisms, functional modifications, enhanced photocatalytic mechanisms, challenges and issues, and directions for future investigations. This review article will act as a theoretical base for researchers who are focused on facet-dependent effects to design and fabricate new photocatalysts.

Automated summary

Facet junction, a complex polyhedral single crystal exposed to multiple crystallographic planes, shows notable facet-crosslinking effects and has potential in promoting the transfer and separation of photogenerated charge carriers. This review article provides an overview of facet junction-based photocatalysts, serving as a theoretical base for researchers focused on facet-dependent effects.