Photoelectrochemical Valorization of Plastic Waste Using Catalytic Silicon Photoanodes

Solar plastic upcycling is demonstrated through the photoelectrochemical oxidation of ethylene glycol derived from real world, pretreated polyethylene terephthalate (PET) bottle waste on an n-Si/Ni photoanode, producing formic acid and glycolic acid with high Faradaic efficiency. The catalytic silicon photoanode promotes efficient interfacial charge transfer under simulated solar illumination in alkaline media, enabling selective oxidation of PET-derived ethylene glycol. Mechanistic insights obtained from electrochemical and spectroscopic analyses indicate that nickel oxyhydroxide species facilitate C─C bond cleavage through surface-bound intermediates. These findings highlight the potential of silicon-based photoanodes as promising platforms for solar-driven plastic waste valorization and sustainable carbon recycling.