Promotion of dual-reaction pathway in CO2 reduction over Pt0/SrTiO3–δ: Experimental and theoretical verification

Abstract

The H2 evolution is generally considered a competing reaction in photocatalytic CO2 reduction reaction (CO2RR) using H2O as the proton source. However, the reducing gas H2 generated from H2O splitting can be the proton source in CO2RR under the enhanced dynamic role of the thermal effect. The reverse water gas shift (RWGS) reaction, a CO2 hydrogenation reaction, should occur in photothermal environment owing to thermodynamically and kinetically favorable. Herein, nanostructured metal-semiconductor contact consisting of Pt nanoparticles (NPs) supported on SrTiO3–δ nanosheets with rich oxygen vacancies (Pt-OVs-STO) was constructed for investigating its feasibility and efficiency in the RWGS reaction under photothermal effect. Our experimental results substantiate that the H2 generated by H2O splitting effectively contributes to the RWGS reaction over Pt-OVs-STO system. The Pt0 NPs not only efficiently facilitate surface charge transfer, but also lower the energy barrier of the O–H bond breaking, H2 releasing, and RWGS reaction, thereby showing an outstanding CO2RR performance. The strong interaction between the Pt0 NPs and SrTiO3–δ has been extensively demonstrated by a series of experimental characterizations and density functional theory calculations. This work elucidates the relation between H2 evolution and RWGS reaction over Pt0/SrTiO3–δ structure in photothermal catalytic CO2RR using H2O as the proton source and provides new perspectives for subsequent CO2RR.