Design of three-dimensional hierarchical TiO2/SrTiO3 heterostructures towards selective CO2 photoreduction

Abstract

Highly selective photocatalytic CO₂ reduction into CO and methane (CH₄) by water vapor is achieved on elaborately designed hollow sphere-based TiO₂/SrTiO₃ heterostructures. The synthesized three-dimensional hierarchical hollow multi-shelled TiO₂/SrTiO₃ spheres (HoMSs-TS) are an assembly of well-organized shells composed of interconnected anatase TiO₂ and perovskite SrTiO₃ nanoparticles (NPs) with an average size of ∼22 nm for each NP. The heterojunctions between TiO₂ and SrTiO₃ provide synergistic enhancement of the charge transfer and separation process, which is critically important in the selective photocatalytic CO₂ reduction reaction (CO₂RR). Moreover, this hierarchical structure features multiple porous subunits, which not only serve to maximize light utilization, but also facilitate mass transport during the photocatalytic process. These advantages empower the HoMSs-TS to effectively suppress hydrogen evolution and ease the selective production of 465 and 4.6 μmol g⁻¹ of CO and CH₄, respectively, over the course of a 24 h reaction.