Photocatalytic degradation of microplastics in aquatic system using metal and non metal- doped TiO₂ catalyst

Microplastics (MPs) are ubiquitous in aquatic environments, posing a serious threat to human health. Photocatalytic degradation is a promising method to mitigate MP pollution owing to high degradation efficiency and low toxicity of by-products. The review analyzes the research progress of photocatalytic degradation of MPs on metal and non metal- doped of TiO₂. Various types of doped precursors used to enhance photocatalytic efficiency. Non-metal precursors obtained from biomass (e.g., shrimp shells, and mussel extracts), organic compounds precursors (e.g., urea, thiourea, and melamine), and carbon-based nanomaterials. Non-metal precursors include biomass, organic compounds, and carbon-based nanomaterials. Metal precursors encompass nitrates, chlorides, organic compounds and MOFs. Key differences between metal and non-metal doping modifications are highlighted. Metal doping is mainly linked to reductive reactive oxygen species (ROS), while non-metal doping is mostly associated with oxidative reactive species and photogenerated holes (h⁺). Such difference is important to control energy levels and generate reactive species. Co-doping and heterostructure construction are also considered to control photocatalytic morphology and electronic structure to enhance the photocatalytic performance under visible light conditions.