CdZnS Nanoparticles Supported on an Ultrathin Cu Metal–Organic Layer as an S-Scheme Photocatalyst for Hydrogen Production and Pollutant Degradation

The carrier separation efficiency and exposure of active sites for photocatalysts are two key factors determining the efficiency of photocatalysis. Minimizing charge carrier recombination while maximizing active site accessibility remains a critical challenge in photocatalytic performance optimization. Herein, an S-Scheme heterojunction composed of two-dimensional (2D) monolayer Cu-5,5′-((anthracene-9,10-diyl)bis(oxy))diisophthalic acid metal–organic layers (CES) and 0D CdZnS nanoparticles (CZS) was designed to improve the kinetics of photocatalytic reactions. The synthesized Cu-MOL exhibited a uniform thickness of approximately 1.98 nm. This ultrathin architecture not only exposed more active sites but also shortened the pathways for mass and charge transfer, thereby enhancing its catalytic activity. In situ irradiated XPS and EPR analysis for DMPO–^•O₂^– signals confirmed an S-scheme charge transfer mechanism, thereby enhancing interfacial charge transfer and preserving a stronger redox ability. As a result, the optimized M₁S₁₀ heterostructure exhibited a high-efficiency photocatalytic hydrogen evolution rate of 124.7 mmol·h^–1·g^–1 under 425 nm light irradiation and a tetracycline hydrochloride (TC) degradation rate of 94% within 40 min. These values significantly surpass those of pure CES (0.1 mmol·h^–1·g^–1 under 380–780 nm, 70% TC degradation) and CZS (43.8 mmol·h^–1·g^–1 under 380–780 nm, 74% TC degradation). This work establishes a viable paradigm for the construction of highly efficient catalysts in solar-to-chemical energy conversion through heterojunction design and morphology modulation.