Engineering stable Pt nanoparticles and oxygen vacancies on defective TiO2 via introducing strong electronic metal-support interaction for efficient CO2 photoreduction

This work for the first time reports the promoting effect of strong electronic metal-support interaction (EMSI) in N/TiO2-V-O (V-O: oxygen vacancy) for gas-phase CO2 photoreduction. A novel in-situ surface hydrogenation was developed to prepare hydrogenated N/TiO2-V-O in a continuous, high throughput diffusion flame aerosol reactor. The combined results of various characterization techniques confirmed the presence of EMSI between N and defective TiO2-V-O resulted in the enhanced electronic density of N nanoparticles. Both the modulated electronic structure of N and surface oxygen vacancies simultaneously promoted the activation of surface adsorbed carbon intermediates and facilitated the separation of photogenerated charges, eventually boosting the photocatalytic activity of N/TiO2-V-O. The optimized N/TiO2-V-O demonstrated a high quantum yield of 1.49% with high CH4 selectivity (81%), which rendered 5.8- and 1.2-fold enhancements over its counterparts of TiO2-V-O and N/TiO2. More significantly, the EMSI also played a critical role in preserving the surface metallic Pt-0 and oxygen vacancies, and in sustaining high activity of the Pt/TiO2-V-O, whereas rapid catalytic deactivation are observed for both TiO2-V-O and Pt/TiO2.