Interface-engineering enhanced photocatalytic conversion of CO2 into solar fuels over S-type Co-Bi2WO6@Ce-MOF heterostructured photocatalysts

Abstract

Development of excellent photocatalysts for efficient conversion CO₂ into renewable fuels is vital to alleviate the problems of greenhouse effect and energy crisis. In this study, we have developed new S-type Co_doped-Bi₂WO₆@Ce-MOF heterostructured photocatalysts by in-situ growing Ce-MOF (cerium metal–organic framework) nanoparticles on the surface of Co-doped Bi₂WO₆ (BWO) hierarchical microflowers. Experimental and theoretical studies demonstrate the formation of S-type heterojunction in the Co-BWO@Ce-MOF hybrids, and the S-type electron transfer from the conduction band of Ce-MOF to the valence band of Co-BWO enables more photoelectrons in the Co-BWO conduction band to participate in the CO₂ photoreduction reactions. Simultaneously, the Co doping reinforces the chemical bonding between Co-BWO and Ce-MOF and enhances the interface electric field, thus promoting the photocarrier transfer. The Co doping also creates abundant oxygen vacancies in Ce-MOF, which are beneficial to the visible-light absorption and photocarrier separation/transfer. Moreover, the Co doping enhances the adsorption/activation of CO₂, promotes electron transfer from the photocatalyst to CO₂ and reduces the energy barriers for the CO₂ reduction through engineering the interface electronic configuration. Owing to these factors, the Co-BWO@Ce-MOF heterostructures are endowed with excellent CO₂ photoreduction activity. Particularly, the Co₁BWO@25CM photocatalytically induces the CO/CH₄ yield rates of 77.1/11.4 μmol g⁻¹ h⁻¹, which are increased by 2.0/1.3 times over those for Co₁BWO and 8.7/8.8 times over those for Ce-MOF. This study highlights that the S-type charge transfer and interface engineering synergistically enhance the CO₂ photoreduction performance of heterojunction photocatalysts.