Sustainable Conversion of Microplastics to Methane with Ultrahigh Selectivity by a Biotic–Abiotic Hybrid Photocatalytic System

Efficient conversion of microplastics into fuels provides a promising strategy to alleviate environmental pollution and the energy crisis. However, the conventional processes are challenged by low product selectivity and potential secondary pollution. Herein, a biotic-abiotic photocatalytic system is designed by assembling Methanosarcina barkeri (M. b) and carbon dot-functionalized polymeric carbon nitrides (CDPCN), by which biodegradable microplastics-poly(lactic acid) after heat pretreatment can be converted into CH₄ for five successive 24-day cycles with nearly 100 % CH₄ selectivity by the assistance of additional CO₂ . Mechanistic analyses showed that both photooxidation and photoreduction methanogenesis worked simultaneously via the fully utilizing photogenerated holes and electrons without chemical sacrificial quenchers. Further research validated the real-world applicability of M. b-CDPCN for non-biodegradable microplastic-to-CH₄ conversion, offering a new avenue for engineering the plastic reuse.