Floatable organic-inorganic hybrid-TiO2 unlocks superoxide radicals for plastic photoreforming in neutral solution

Abstract

Plastic photoreforming offers a compelling technology to address the global issue of the large amount cumulative plastic waste by converting it into valuable fuels and chemical feedstocks. However, constrained by insufficient mass and energy transfers, the existing hydrophilic plastic photoreforming systems heavily rely on the unsustainable chemical pre-treatments in corrosive solutions. Herein, we demonstrate a conceptual plastic photoreforming system based on a floatable hydrophobic organic-inorganic hybrid-TiO₂ photocatalyst, which unlocks superoxide radical as the major oxidizing species and forms a four-phase interface among photocatalyst, plastic substrate, water and air, thus greatly enhancing the mass and energy transfers. Consequently, the photoreforming yield rates in neutral aqueous solutions are increased by 1–2 orders of magnitude for typical plastic including polyethylene, polypropylene, and polyvinyl chloride without applying pre-treatments, whilst producing high-value C₂H₅OH with a selectivity of over 40%. We believe this work reveals a feasible route to sustainable plastic photoreforming.