Synergistically boosted Z-scheme CO2 photo-conversion via epitaxial interface construction and oxygen vacancy engineering

Abstract

Z-scheme photocatalysts with an epitaxial heterogeneous/hetero-phase interface and a strengthened charge-transport driving force are intriguing for efficient solar photocatalysis. However, the relevant study has been frequently obstructed by the large lattice mismatch among different components and their differing crystal growth preferences. In this study, ultrathin bronze-phase TiO₂ nanosheets (TB NSs) were grown epitaxially onto anatase TiO₂ nanobelts (AT NBs) with their basal planes parallel to the latter’s stretching direction, deriving the epitaxial AT-TB hetero-phase architectures (HPAs). Noticeably, the epitaxial interface helps to minimize the scattering and energy quenching of transferred charge carriers. Moreover, the internal electric field (IEF) of AT-TB HPAs can be strengthened by amplifying the Fermi level gap between AT and TB via oxygen vacancy engineering, which contributes to driving Z-scheme charge transmission effectively. When tested for gas-solid photocatalytic CO₂ conversion, AT-TB epitaxial HPAs exhibited a much superior activity than individual AT NBs and TB NSs, as well as TB-TB epitaxial hierarchitectures without phase-junction. Additionally, the photocatalytic capability of AT-TB HPAs was further notably promoted via site-specific Pd photo-deposition, achieving the CO and CH₄ evolution rates of 48.53 and 16.41 µmol g⁻¹ h⁻¹, outperforming that of many TiO₂-based photocatalysts reported before. Our study could inspire efficient Z-scheme photocatalysis by epitaxial interface construction and vacancy engineering.