Precisely Controlled Relationship between Sulfur Vacancy and Ni Site for Boosting Photocatalytic Conversion of Polyester into Formate

Abstract The photoreforming of plastic waste into high‐value chemicals and H ₂ fuels presents a sustainable and energy‐efficient strategy to mitigate environmental pollution and energy crises. However, achieving high selective valuable products remains challenging due to the indiscriminate cleavage of chemical bonds in plastics. Herein, this study reports a sulfur‐vacancies‐rich ZnIn ₂ S ₄ photocatalyst decorated with ultrafine Ni nanoparticles (Ni _0.2 @ZIS‐S _v ) that enables highly photoreforming of poly(ethylene terephthalate) (PET) into formate and H ₂ via targeted C─C bond cleavage under mild alkaline conditions. The Ni _0.2 @ZIS‐S _v photocatalyst achieves an H ₂ evolution rate of 4.5 mmol g ⁻¹ h ⁻¹ , a 20.2‐fold enhancement over pure ZnIn ₂ S ₄ , while formate is the primary liquid product with the selectivity reaching 84.8%. Mechanistic analysis reveals that the combined effects of Ni nanoparticles and sulfur‐vacancies modify the electronic structure of ZnIn ₂ S ₄ , improving charge separation, lowering the energy barrier for H ₂ generation, and facilitating selectively C─C bond cleavage. This dual optimization enhances both hydrogen yield and formate selectivity, demonstrating an effective strategy for designing advanced photocatalysts to upcycle plastic waste into high‐value chemicals and clean energy.