In Situ Characterizations Revealing Ruthenium-Atom-Induced Raise of Photocatalytic Performance

Rational design/fabrication of high-activity photocatalysts is of central importance to realize solar-to-chemical conversion for tackling worldwide energy/environmental issues. Hence, it is desirable to disclose the element/space/time-resolved charge kinetics and surface species evolution of photocatalysts under realistic conditions using various in situ characterizations. Furthermore, the correlation of the above-disclosed mechanisms with atomic-scale compositions/structures of photocatalysts can further direct the atomic-level design/synthesis of high-performance photocatalysts. Herein, Ru atoms incorporated CdS quantum dots (QDs) are synthesized using an in situ hot-injection route. The optimized Ru incorporated CdS QDs (Ru0.1) exhibit excellent photocatalytic evolution rates of H₂O₂ (8.78 mmol g⁻¹ h⁻¹) and benzaldehyde (11.70 mmol g⁻¹ h⁻¹), respectively. Four different in situ characterizations demonstrate that in realistic conditions, the incorporated Ru atoms with high oxidation state (+3) effectively attract photo-generated electrons from bulk to the overall surface of Ru0.1; these directed electron flows also greatly facilitate the transfer of photo-generated holes from bulk to surface of Ru0.1 via efficiently reducing electron-hole recombination. in situ diffuse reflectance infrared Fourier transform spectroscopy, electron spin spectroscopy, and species-trapping experiments further reveal three possible reaction pathways for H₂O₂ evolution. This work underscores the use of in situ characterizations to reveal the element/space/time-resolved electrons/holes kinetics and surface-species generation for photocatalysts in realistic conditions.