Cu0/Cu+-Modified Monoclinic TiO2(B) Nanoflowers with Oxygen Vacancies for Efficient Visible-Light-Driven Photocatalytic Reduction of CO2

Abstract

The photoreduction of CO₂ has attracted extensive attention as a promising solution to global warming. In this study, Cu-modified TiO₂(B) (CuTB) nanoflowers with oxygen vacancies (OVs) are designed and synthesized via hydrothermal treatment and photodeposition to promote the reactivity and selectivity of CO₂ reduction to CO under visible light. The CO and CH₄ yields of sample Cu₁TB-1.5 under visible light are 5.72 and 0.02 μmol g⁻¹ h⁻¹, wherein the CO yield was 15.5 times that of sample TB; its selectivity is 99.6%, and the cycling stability is excellent. OVs can broaden the light absorption of TB to the visible light region, and Cu promotes photoinduced electron transfer from TB to the Cu species and act as an active center. The OVs and Cu can synergistically enhance charge separation, CO₂ adsorption, and CO₂ conversion. The Cu₁TB-1.5 facilitates the formation of the intermediate COOH* during the photocatalytic process, thus improving the yield and selectivity of CO. This research provides a unique idea for the development of novel highly selective photocatalysts.