Recent advancements of layered double hydroxide heterojunction composites with engineering approach towards photocatalytic hydrogen production: A review

Photocatalytic hydrogen production has been considered as one of the most promising alternatives for providing clean, sustainable, and renewable energy sources. Tremendous investigation and efforts have been devoted to increase the efficiency of the solar to energy conversion of a photocatalyst. Layered double hydroxide (LDH) received scientific attention for its excellent compositional flexibility and controllable morphology, leading to the facile incorporation of the metal species into their layered structure. The unique multi-structure and the tunability of its band gap make LDH more prominent in the field of photocatalysis. This article highlights the recent developments in the fabrication of LDH-based photocatalyst nanocomposites and the engineering approaches for augmenting their photocatalytic hydrogen production efficiency. The thermodynamics and challenges in photocatalytic water splitting are deliberated to understand the pathways to construct efficient semiconductor photocatalysis system. The efficiency enhancement of LDH-based photocatalysts are comprehensively discussed by giving special attention to the heterojunction engineering of type I, type II, p-n junction, Z-scheme, S-scheme, and R-scheme. Fabrication of the hybrid LDH nanocomposites through band gap engineering and metal loading are summarised. The architectural and morphological tuning of LDH-based composite through the construction of the novel core-shell structure and layer-by-layer nanosheets are also demonstrated. Finally, the future recommendations are outlined to provide insights for their development in the photocatalysis field.