Turning Waste into Valuable Products: Sunlight-Driven Hydrogen from Polystyrene via Porous Tungsten Oxide Photoanodes

Abstract

The photochemical conversion of plastic waste into valuable resources under ambient conditions is challenging. Achieving efficient photocatalytic conversion necessitates intimate contact between the photocatalyst and plastic substrate, as water molecules are readily oxidized by photogenerated holes, potentially bypassing the plastic as the electron donor. This study demonstrated a novel strategy for depositing polystyrene (PS) waste onto a photoanode by leveraging its solubility in specific organic solvents, including acetone and chloroform, thus enhancing the interface contact. We used an anodization technique to fabricate a skeleton-like porous tungsten oxide (WO3) structure, which exhibited higher durability against detachment from a conductive substrate than the WO3 photoanode fabricated using the doctor blade method. Upon illumination, the photogenerated holes were transferred from WO3 to PS, promoting the oxidative degradation of plastic waste under ambient conditions. Consequently, the oxidative degradation of PS on the anode side generated carbon dioxide, while the cathodic process produced hydrogen gas through water reduction. Our findings pave the way for sunlight-driven plastic waste treatment technologies that concurrently generate valuable fuels or chemicals and offer the dual benefits of cost savings and environmental protection.