LDH-based nanomaterials for photocatalytic applications: A comprehensive review on the role of bi/trivalent cations, anions, morphology, defect engineering, memory effect, and heterojunction formation

Using sunlight to drive chemical reactions via photocatalysis is paramount for a sustainable future. Among several photocatalysts, employing layered double hydrides (LDH) for photocatalytic application is most straightforward and desirable owing to their distinctive two-dimensional (2D) lamellar structure and optical attributes. This article reviews the advancements in bimetallic/trimetallic LDHs and various strategies to achieve high efficiency toward an outstanding performing photocatalyst. Firstly, the tuning of LDH components that control the electronic and structural properties is explained. The tuning obtained through the adoption, combination, and incorporation of different cations and anions is also explained. The progress of modification methods, such as the adoption of different morphologies, delamination, and defect engineering towards enhanced photocatalytic activities, is discussed in the mainstream. The band engineering, structural characteristics, and redox tuning are further deliberated to maximize solar energy harvesting for different photocatalytic applications. Finally, the progress obtained in forming hierarchical heterostructures through hybridization with other semiconductors or conducting materials is systematically disclosed to get maximum photocatalytic performance. Moreover, the structural changes during the in-situ synthesis of LDH and the stability of LDH-based photocatalysts are deliberated. The review also summarizes the improvements in LDH properties obtained through modification tactics and discusses the prospects for future energy and environmental applications.