Design and engineering of heterogeneous photocatalysts for plastic degradation and upcycling

Solar-driven heterogeneous photocatalysis offers a promising route for the degradation and upcycling of plastic waste under ambient temperature and pressure. This review summarizes recent progress in this field, with particular focus on reaction mechanisms, active-site engineering, and regioselective bond scission (C–C, C–O, and C–N). We first discuss polymer activation thermodynamics and interfacial radical dynamics to clarify the origin of product selectivity. Next, we evaluate major catalyst platforms, including metal oxides, metal sulfides, carbon-based materials, layered double hydroxides (LDHs), metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and single-atom catalysts (SACs), alongside engineering strategies to improve performance. Finally, key practical considerations, such as continuous-flow reactors, operational stability, and techno-economic feasibility, are critically assessed to highlight future research directions.