Simultaneous hydrogen production and conversion of plastic wastes into valued chemicals over a Z-scheme photocatalyst

Abstract

Solar-powered photoreforming of plastics provides a facile and low-energy pathway for generating green hydrogen while converting plastic wastes into valuable organic compounds. Herein, a Z-scheme photocatalyst, containing Cd0.5Zn0.5S for hydrogen production, red phosphorus (RP) for oxidizing plastics, and CoxPy as the electron mediator, was constructed. The photoreforming of polylactic acid (PLA) and polyethylene terephthalate (PET) was carried out under alkaline aqueous conditions. The photogenerated electrons from the RP recombined with the holes from Cd0.5Zn0.5S. The retained electrons in Cd0.5Zn0.5S reduced water to hydrogen, whereas the holes in the RP oxidized plastic-derived polymers into valuable organic products, such as pyruvate, acetate, and methanol. The hydrogen evolution rates from the photoreforming of PLA and PET using the optimal photocatalyst at 35 °C reached 503.9 and 74.4 μmol h−1, corresponding to the apparent quantum efficiencies of 5.84 % and 0.89 % at 420 nm.