Promoting CO2 and H2O activation on O-vacancy regulated In-Ti dual-sites for enhanced CH4 photo-production

Abstract

The oxygen-vacancy (V O ) regulated In-Ti dual sites are created on porous TiO 2 for CO 2 photoreduction , where V O s accelerate H 2 O dissociation and the In-Ti dual sites enable the formation of In-C-O-Ti intermediate conformation for CH 4 generation. Engineering the specific active sites of photocatalysts for simultaneously promoting CO 2 and H 2 O activation is important to achieve the efficient conversion of CO 2 to hydrocarbon with H 2 O as a proton source under sunlight. Herein, we delicately design the In/TiO 2 -V O photocatalyst by engineering In single atoms (SAs) and oxygen vacancies (V O s) on porous TiO 2 . The relation between structure and performance of the photocatalyst is clarified by both experimental and theoretical analyses at the atomic levels. The In/TiO 2 -V O photocatalyst furnish a high CH 4 production rate up to 35.49 μmol g −1 h −1 with a high selectivity of 91.3% under simulated sunlight, while only CO is sluggishly generated on TiO 2 -V O . The combination of in situ spectroscopic analyses with theoretical calculations reveal that the V O sites accelerate H 2 O dissociation and increase proton feeding for CO 2 reduction. Furthermore, the V O regulated In-Ti dual sites enable the formation of a stable adsorption conformation of In-C-O-Ti intermediate, which is responsible for the highly selective reduction of CO 2 to CH 4 . This work demonstrates a new strategy for the development of effective photocatalysts by coupling metal SA sites with the adjacent metal sites of support to synergistically enhance the activity and selectivity of CO 2 photoreduction.