Efficient Photoredox Co-Upcycling of CO₂ and Plastic Waste by Band-Gap-Engineered Zn_xCd_1–xS Catalyst

Solar-driven CO 2 reduction combined with plastic waste valorization presents a versatile approach to simultaneously reset misaligned hydrocarbon resources and achieve a carbon-neutral cycle. Herein, we demonstrate a co-upcycling heterogeneous photoredox catalysis for efficient CO 2 reduction to tunable syngas, integrated with polyethylene terephthalate (PET) plastic conversion for accessing acetate, over the spherical band-gap-engineered Zn x Cd 1– x S catalyst. The key to steering the syngas H 2 /CO rate is to modulate the conduction band bottom potentials of the Zn x Cd 1– x S photocatalysts by altering the Zn/Cd ratio, which results in syngas H 2 /CO production over a wide range. Moreover, controlled variations in the molar ratio of Zn/Cd regulate the electron–hole separation capability, thereby endowing Zn 0.8 Cd 0.2 S with the optimum syngas and acetate production rates. The underlying mechanistic origin of such a redox reaction involving CO 2 -assisted PET plastic conversion has been systematically investigated. This win-win cooperative photoredox catalysis offers a tantalizing possibility for co-upcycling of CO 2 and PET into value-added feedstocks.