Ultrahigh Bifunctional Photocatalytic CO2 Reduction and H2 Evolution by Synergistic Interaction of Heteroatomic Pt–Ru Dimerization Sites

Diatomic-site catalysts (DASCs) inherit the excellent performance of single-atom catalysts (SACs) by utilizing two adjacent atomic metal species to achieve functional complementarity and synergistic effects that improve the carbon dioxide reduction reaction (CO₂RR) and H₂ evolution reaction (HER) kinetics. Herein, we report a method to further improve the catalytic efficiency of Pt by using Pt and Ru single atoms randomly anchored on a g-C₃N₄ surface, yielding partial Pt–Ru dimers. The synthesized catalyst exhibits extraordinary photocatalytic activity and stability in both the CO₂RR and HER processes. In-depth experimentation, the pH-dependent chemical exchange saturation transfer (CEST) imaging nuclear magnetic resonance (NMR) method, and theoretical analyses reveal that the excellent performance is attributed to orbital coupling between the Pt atoms and the neighboring Ru atoms (mainly d_xy and d_xz), which decreases the orbital energy levels and weakens the bond strength with intermediates, resulting in improved CO₂RR and HER performance. This study successfully applies the pH-dependent CEST imaging NMR method to catalytic reactions, and CO₂ adsorption is directly observed using CEST 2D imaging maps. This work presents significant potential for a variety of catalytic reaction applications by systematically designing bimetallic dimers with higher activity and stability.