Selective Oxidation of Polyesters via PdCu–TiO₂ Photocatalysts in Flow

Catalytic upcycling of plastic wastes offers a sustainable circular economy. Selective conversion of the most widely used polyester, polyethylene terephthalate (PET), under ambient conditions is practically attractive because of low energy consumption and carbon footprint. Here, we report selective, aerobic conversion of PET in a flow reactor using TiO₂ photocatalyst modified with atomic Pd and metallic PdCu (Pd₁Cu_0.4-TiO₂) under ambient conditions. We demonstrate that atomically synergistic Pd₁Cu_0.4-TiO₂ exhibits a formate evolution of 4707 μmol g^-1 h^-1 with a selectivity of 92.3% together with trace CO_<i>x</i> released. Importantly, we show that this corresponds to 10-10³ times greater activity than reported photocatalytic systems. We confirm that synergy between atomic Pd and metallic PdCu boosts directional charge transfer and oxygen-induced C-C cleavage and inhibits product decomposition. We conclude that photocatalytic waste plastic-to-chemical conversion is sustainable via targeted engineering of atomically synergistic catalysts and reaction systems.