State-of-the-art developments in metal/metal oxide and graphene-based nano-hybrid systems for photocatalytic degradation of tetracycline antibiotics

An efficient method to degrade Tetracyclines (TCs) in wastewater is through photocatalysis. In recent years, some of the study has been reported on doped photocatalysts and heterostructure nanomaterial-based photocatalytic systems. However, these reports have not been critically reviewed in the literature. Herein, we comprehensively reviewed various metal/metal oxide and graphene based photocatalysts along with their mechanistic detail to degrade the tetracycline. We compare the efficiency of TC degradation among various metal/metal oxide-doped nanocomposites (NCs) and quantum dots/ carbon nanotube/ graphene based nanocomposites depending on their doping elements, synthesis methods, electron transport properties, charge recombination, and reactive radical species (^•OH, h⁺ and ^•O₂^–). Additionally, various metal/metal oxide and graphene based heterojunctions offer a promising opportunity for effective TC degradation, with future research focusing on developing high-quality, advanced materials through energy-efficient processes that are minimally toxic and cost-effective. In particular, the formation of heterojunctions between g-C₃N₄ and semiconductor nanostructures using Type II or Z-scheme mechanisms is expected to be a significant research focus in the near future.