Photoelectrochemical Reforming of PET Plastics using a Ternary CoOCl/SrTiO₃/TiO₂ Heterojunction Membrane Electrode

Photoelectrochemical (PEC) upcycling of plastic waste into value-added chemicals and hydrogen fuel offers a sustainable approach to mitigate pollution while producing clean energy. Here, we report a flow-through ternary heterojunction membrane photoanode (CoOCl/SrTiO₃/TiO₂) that integrates membrane-confined mass transport with self-adaptive cocatalyst reconstruction to enable selective PET photoreforming. The optimized CoOCl/SrTiO₃/TiO₂ membrane achieves a GA production rate of 10.76 µmol cm^-2 h^-1 with 80% selectivity, alongside a hydrogen evolution rate of 4.49 µmol cm^-2 h^-1, significantly outperforming TiO₂ and SrTiO₃/TiO₂ binary photoanodes. Post-reaction analysis reveals that CoOCl undergoes ion displacement reactions in the alkaline electrolyte and reconstructs into β-CoOOH, which serves as an efficient hole transfer cocatalyst and drives selective oxidation of ethylene glycol from PET via a ¹O₂ pathway. This dynamic reconstruction ensures high durability over repeated cycles (7% decay after five cycles). Such monolithic flow-through membrane architecture and reconstruction of CoOCl into β-CoOOH synergistically enhance mass transport, charge utilization, and oxidation selectivity. This work thus establishes a membrane photoelectrode technology for sustainable plastic valorization and solar fuel production.