Interfacial engineering of TiO2@Bi-BiOBr by constructing hierarchical core–shell heterojunction to boost charge transfer for photothermal CO2 reduction

[Display omitted] •Heterojunction materials with hierarchical hollow core–shell structure TiO2@Bi-BiOBr was successfully synthesized.•Electron transfer modes at the interface of TiO2@Bi-BiOBr composite demonstrated.•The TiO2@Bi-BiOBr composite exhibits superior photothermal catalytic CO2 reduction to CO performance. CO2 reduction by a sustainable pathway such as photothermal catalysis is highly demanded currently, high carrier recombination rate still severely limits the performance of photothermal catalysis. Constructing heterojunction interfaces with high exposed area is an effective strategy to solve the problem of carrier recombination. However, fine control of the interface structure is still highly challenging. Herein, Density functional theory (DFT) calculations were constructed to reveal that metallic Bi leads to more densities of states (DOS) generation at the conduction band edge in Bi-BiOBr, which argues that photogenerated electrons are more likely to be delivered to metallic Bi. A TiO2@Bi-BiOBr hollow hierarchical core–shell heterojunction was designed, providing a highly exposed interface and Bi between interfaces. Such structure endows the catalyst with excellent photothermal catalytic performance, achieving a CO yield of 30.4 μmol·h−1·g−1. The highly improved performance is attributed to interfacial thermoelectrons transfer boosted by the construction of TiO2@BiOBr heterojunction as well as metal Bi. And a possible CO2 reduction pathway is proposed, which is consistent with the Carbine pathway. This study provides an exciting idea for the modulation of photoelectron transfer at catalyst interfaces.