Photocatalytic Upcycling of Plastic Waste into Syngas by ZnS/Ga2O3 Z-Scheme Heterojunction

Abstract

The photocatalytic conversion of plastic waste into value-added products using solar energy presents a promising approach for promoting environmental sustainability. Nonetheless, the emission of CO₂ during the conventional photocatalytic degradation process remains a major hurdle that impedes its further development. In this study, we propose an efficient photocatalytic conversion of polyethylene plastic into syngas (CO+H₂ mixtures) by using a ZnS/Ga₂O₃ Z-scheme heterojunction photocatalyst. It is found that the strong redox capability of photogenerated holes and electrons in the Z-scheme heterojunction photocatalyst can promote the oxidative depolymerization of PE plastic, concurrently enabling the efficient reduction of the intermediate product CO₂ into syngas. Furthermore, this system also demonstrates applicability in the conversion and upcycling of other polyolefin plastics including polypropylene and polyvinyl chloride. Our findings highlight the potential of polyolefin plastics photoreforming for the production of syngas under environmentally benign conditions.