Construction of dual-single-atom sites: Pt-Cu/VTNT and Pd-Cu/VTNT for efficient photocatalytic hydrogen evolution

Single-atom catalysts (SACs) offer unique advantages for photocatalysis, but the modulation of charge carrier dynamics remains challenging. Here, we demonstrate that dual-single-atom catalysts (DSACs) address this limitation by introducing two kinds of metal atoms to cooperatively tune the electronic structure. Using density functional theory (DFT) calculations, we elucidated the synergistic mechanism by which Pt-Cu DSACs enhance photocatalytic activity. The calculations revealed that atomic-scale interactions between Pt-Cu and TiO2 form a Schottky barrier, directing interfacial charge transfer, optimizing the hydrogen adsorption free energy (ΔGH*) and modifying the band structure. Guided by these theoretical insights, we precisely constructed Pt-Cu and Pd-Cu DSACs on TiO2 nanotubes rich in oxygen vacancies (VTNT). The photocatalytic hydrogen evolution (PHE) performance was significantly enhanced by the optimized DSACs Pt-Cu/VTNT and Pd-Cu/VTNT, which achieved hydrogen evolution rates of 3575.36 and 3199.52 μmol h−1 gcat.−1, respectively, significantly surpassing their SACs counterparts. Experimental characterization confirmed the predicted interfacial charge-transfer behavior and band-structure modifications, validating the theoretical model. This work establishes a complete framework from theoretical prediction to experimental validation, providing a rational design strategy for advanced photocatalysts leveraging atomic-scale cooperative effects.