Copper and platinum dual-single-atoms supported on crystalline graphitic carbon nitride for enhanced photocatalytic CO2 reduction

Single-atom Pt catalysts are designed to promote efficient atom utilization, whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing. Atomically dispersed metal species in crystalline carbon nitride are still challenging owing to their high crystallization and structural stability. In this study, we developed a novel single-atomic Pt-Cu catalyst for reducing noble metal loading by combining Pt with earth-abundant Cu atoms and enhancing photocatalytic CO2 reduction. N-vacancy-rich crystalline carbon nitride was used as a fine-tuning ligand for isolated Pt-Cu atom dispersion based on its accessible functional N vacancies as the seeded centers. The synthesized dimetal Pt-Cu atoms on crystalline carbon nitride (PtCu-crCN) exhibited high selectivity and activity for CO2 conversion without the addition of any cocatalyst or sacrificial agent. In particular, we demonstrated that the diatomic Pt-Cu exhibited high mass activity with only 0.32 wt% Pt loading and showed excellent photocatalytic selectivity toward CH4 generation. The mechanism of CO2 photoreduction for PtCu-crCN was proposed based on the observations and analysis of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images, in situ irradiated X-ray photoelectron spectroscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy. The findings of this work provide insights for abrogating specific bifunctional atomic metal sites in noble metal-based photocatalysts by reducing noble metal loading and maximizing their effective mass activity.

Automated summary

In this study, a novel Pt-Cu single-atom catalyst was developed to reduce noble metal loading and improve photocatalytic activity. By combining Pt with Cu atoms, the catalyst exhibited high selectivity and activity for CO2 reduction. The use of N-vacancy-rich crystalline carbon nitride as a ligand enabled the dispersion of Pt-Cu atoms, resulting in high mass activity with low Pt loading. The findings provide insights for the design of efficient noble metal-based photocatalysts.