Coupling of Cu Catalyst and Phosphonated Ru Complex Light Absorber with TiO2 as Bridge to Achieve Superior Visible Light CO2 Photoreduction

Abstract

Visible light photocatalytic CO2 conversion is a promising solution to global warming and energy shortage. Herein, we build a well-designed bridge-like nanostructure, that is, the phosphonated Ru complex (RuP) light absorber–TiO2 bridge–Cu catalyst. In this nanostructure, brookite TiO2 serving as a bridge is spatially connected to the RuP and Cu on each of its sides and could thus physically separate the photoexcited holes and electrons over the RuP and Cu, respectively. Given its effective charge separation, this RuP–TiO2–Cu assembly exhibits superior CO2 photoreduction activity relative to RuP–SiO2–Cu under visible light irradiation (λ > 420 nm). The catalytic activity is further optimized by adopting brookite TiO2 with various electronic band structures. Results reveal the rapid movement of electrons from the RuP through the conduction band of TiO2 and finally to the Cu surface. This property is crucial in CO2 photoreduction activity.