Clay materials including clay minerals and layered double hydroxides (LDHs) have attracted great attention because of their special layer structures, large specific surface areas, and remarkable adsorption capacities. In the past few decades, they have been regarded as important components or precursors for making various functional materials. This paper aims to review and summarize the recent advances in the synthesis and photocatalytic applications of clay-based photocatalysts. Moreover, the effects of surface and structural characteristics of clay-based photocatalysts on photocatalytic properties are also discussed. The clay-based photocatalysts show good application prospects for environmental remediation and energy conversion. Especially, H₂ generation and reduction of CO₂ into carbon sources can be easily achieved using the LDH-based photocatalysts. Meanwhile, the role of clay materials in the photocatalysis is discussed in detail.

A novel AgI/Bi ₂ Ga ₄ O ₉ p–n junction photocatalyst was synthesized by an electrostatic self-assembly approach. Characterization and DFT calculations show that the formation of the p–n junction greatly boosts the generation of superoxide radicals.

In this study, Zn₂GeO₄ hollow spheres were successfully fabricated by a template-engaged approach using zinc hydroxide carbonate (Zn₄CO₃(OH)₆·H₂O, ZHC) spheres as the template. During the hydrothermal process, Zn²⁺ dissolved from the surface of the ZHC spheres could rapidly react with the HGeO₃ ⁻ in solution and the Zn₂GeO₄ outer shell was formed in situ. Moreover, the building units of the Zn₂GeO₄ hollow spheres could gradually transform from the nanoparticles into nanobundles with the increase of the reaction time. The photocatalytic degradation results indicate that the Zn₂GeO₄ hollow spheres exhibited high photocatalytic activity and excellent stability for the degradation of antibiotic metronidazole in solution. Finally, the radical species involved in the degradation process have been investigated by using the scavenger experiments.