Bonding Interaction of Adjacent Pt and Ag Single-Atom Pairs on Carbon Nitride Efficiently Promotes Photocatalytic H2 Production

Dual-atom catalysts (DACs) represent an exciting advance in the field of heterogeneous catalysis. They not only retain the beneficial characteristics of single-atom catalysts (SACs), but they also harness the synergistic effects that arise from the proximity of neighboring single-metal atoms. Nevertheless, the fabrication of heteronuclear dual-atom metals positioned adjacently for use in photocatalysis remains a significant challenge. Herein, we report the atomically dispersed adjacent Pt–Ag dual-atom pairs on carbon nitride (Pt₁Ag₁-a/CN) by a facile hydrogen-bonding assembly strategy via pyrolysis of the hydrogen-bonding supramolecule containing melamine-Ag and cyanuric acid-Pt complexes on carbon nitride (CN), through which the light absorption depressed by deposited carbonaceous materials during the preparation of dual-atom metals via a traditional method like the pyrolysis of the metal–organic framework. Thanks to the synergism achieved by the bonding interaction of adjacent Pt and Ag single-atom pairs, the developed Pt₁Ag₁-a/CN with 0.21% Pt loading shows a high turnover frequency (TOF) of 1115 h⁻¹ with a H₂ evolution rate (HER) of 12,000 µmol g⁻¹ h⁻¹ for photocatalytic water splitting under simulated solar light irradiation (325 h⁻¹ of TOF with 3480 µmol g⁻¹ h⁻¹ of HER under visible light irradiation). This strategy outperforms the previously reported SACs on CN-based semiconductors. Density functional theory (DFT) calculations demonstrate that the adjacent Ag atom acts as a coordination atom to effectively regulate the electronic structure of the Pt atom and thus brings the d-band center of Pt close to the Fermi energy level, which is beneficial for the H₂ production. This work presents a facile and general strategy for designing diverse adjacent diatomic cocatalysts in photocatalysis without depressing light absorption by the deposited carbon during the DAC preparation via previously reported methods.