Photo-induced oxidative degradation of polystyrene waste by a surface-modified heterogeneous titanium catalyst in air

Abstract

A photocatalytic protocol employing a surface-modified heterogeneous TiO₂ catalyst is developed for the selective conversion of polystyrene (PS) waste into aromatic ketones or acids in ambient air by tuning pivalic acid (PivOH) loading. Surface modification by Ni reduces the band gap of TiO₂ and thereby enhances the visible-light (blue LED) activity of the catalyst. Mechanistic insights suggest superoxide radical-induced C–H activation followed by C–C scission through a photo-hydrogen atom transfer (HAT) pathway. The catalyst exhibits excellent recyclability, offering a sustainable route for PS valorization.