Solar‐Driven Photocatalytic C─S Coupling for Organosulfur Synthesis Via Upcycling SO ₂ and Plastic Waste

ABSTRACT Hydroxymethylsulfonate (HMS) is an important cleaning agent in the electronics industry and serves as a crucial intermediate in the synthesis of surfactants and pharmaceuticals. Conventional industrial production of HMS relies on toxic and volatile formaldehyde, presenting considerable safety and environmental risks. Herein, we report a solar‐driven photocatalytic route for the synthesis of HMS from waste SO 2 and polyethylene terephthalate (PET)‐derived ethylene glycol (EG) under ambient conditions, using a Cu single‐atom‐decorated TiO 2 catalyst (Cu 1 /TiO 2 ). The optimized Cu 1 /TiO 2 catalyst achieves an HMS yield rate of ∼ 2.31 mmol g cat −1 h −1 with a 77.5% carbon selectivity, along with a H 2 evolution rate of ∼ 4.36 mmol g cat −1 h −1 . Mechanistic studies reveal that the atomically dispersed Cu sites act as electron sinks, which enhance charge separation and induce electronic modulation of TiO 2 . This modulation facilitates the adsorption and activation of reactants while lowering the energy barrier for the formation of a key *CHOH─CH 2 OH intermediate via EG dehydrogenation. This resulting intermediate then undergoes nucleophilic attack by hole‐generated •SO 3 − , triggering C─C cleavage to form HMS. This work establishes a sustainable and waste‐valorizing route for organosulfur synthesis.