Hydroxyl-Bonded Ru on Metallic TiN Surface Catalyzing CO 2 Reduction with H 2 O by Infrared Light.

Synchronized conversion of CO 2 and H 2 O into hydrocarbons and oxygen via infrared-ignited photocatalysis remains a challenge. Herein, the hydroxyl-coordinated single-site Ru is anchored precisely on the metallic TiN surface by a NaBH 4 /NaOH reforming method to construct an infrared-responsive HO-Ru/TiN photocatalyst. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (ac-HAADF-STEM) and X-ray absorption spectroscopy (XAS) confirm the atomic distribution of the Ru species. XAS and density functional theory (DFT) calculations unveil the formation of surface HO-RuN 5 -Ti Lewis pair sites, which achieves efficient CO 2 polarization/activation via dual coordination with the C and O atoms of CO 2 on HO-Ru/TiN. Also, implanting the Ru species on the TiN surface powerfully boosts the separation and transfer of photoinduced charges. Under infrared irradiation, the HO-Ru/TiN catalyst shows a superior CO 2 -to-CO transformation activity coupled with H 2 O oxidation to release O 2 , and the CO 2 reduction rate can further be promoted by about 3-fold under simulated sunlight. With the key reaction intermediates determined by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and predicted by DFT simulations, a possible photoredox mechanism of the CO 2 reduction system is proposed.