Pt Sub-Nanoclusters on ZIF-Derived Ultrafine Cd_xZn_1−xS Solid Solution: High-Performance Photoreforming Lactic Acid to H₂ and Value-Added Chemicals

Solar-driven H₂ production coupled with selective organic transformation represents a promising strategy for co-generation of green hydrogen and high-value chemicals, yet its feasibility relies critically on effective bifunctional photocatalysts. Herein, we report the synthesis of ultrafine Cd_xZn_1−xS nanocrystals derived from a zeolitic imidazolate framework (ZIF), featuring high surface area, shortened charge diffusion path, and enhanced H₂ evolution activity. Anchoring amorphous Pt sub-nanoclusters onto these nanocrystals created a bifunctional catalyst (Pt-Cd_xZn_1−xS) for efficient lactic acid photoreforming, enabling co-production of H₂ with switchable selectivity toward pyruvic acid (PA) or 2,3-dihydroxy-2,3- dimethylsuccinic acid (DTA). The optimized 0.5Pt-Cd_0.3Zn_0.7S catalyst achieved an exceptional H₂ production rate of 270.6 mmol h⁻¹ g⁻¹, 73.1% PA selectivity, and 62.8% apparent quantum efficiency at 400 nm. Mechanistic studies revealed that lactic acid undergoes C-H cleavage to form carbon-centered radicals. Pt sub-nanoclusters served as electron sinks to facilitate O-H dissociation and PA formation, whereas pristine Cd_0.3Zn_0.67S promoted direct C-C coupling of radicals to predominantly yield DTA. This work offers critical insights for designing advanced bifunctional photocatalysts to integrate solar hydrogen and value-added chemical synthesis.