Constructing a Bi–O–Mo electronic bridge bond and active sites over Bi/Bi2MoO6/Bi24O31Br10 to boost the stepwise transfer of electrons for efficient CO2 photoreduction

Abstract

The high interfacial charge transfer barrier has been a primary thermodynamic obstacle in enhancing the catalytic performance of heterojunction materials. Optimizing the interfacial environment is a promising strategy to attain superior catalytic efficiency. Hence, a Bi/Bi₂MoO₆/Bi₂₄O₃₁Br₁₀ (Bi/BMO/BOB) composite photocatalyst was constructed by introducing a Bi–O–Mo bridge bond between the BMO and BOB interfaces and modifying metal active sites on the surface of the complex. Bi/BMO/BOB has a good capacity for CO₂ photoreduction to CO. The CO yield of the Bi/BMO/BOB photocatalyst is 68.29 μmol g⁻¹ h⁻¹, which is obviously higher than those of the pristine BMO and BOB. As proved by density functional theory (DFT) calculations and experimental characterization, the Bi–O–Mo interface bridge bond adjusts the electronic structure of the contact interface and enhances the interface charge separation and transport rate. Moreover, the metal Bi nanoparticles synthesized through in situ reduction not only realize electron transfer and storage as electron collectors, but also strengthen the adsorption of CO₂ molecules. The synergistic action of the two can allow the effective transfer of photogenerated electrons from BMO to BOB, which then accumulate on Bi. Such stepwise transfer of electrons increases the speed of photocatalytic reduction processes that involve multiple electrons, and effectively reduces the reaction energy barrier in the process of CO₂ reduction. This mode of interatomic electron transfer bridges combined with the metal active sites not only solves the stability issues in bismuth-based semiconductors, but also aids in the development of more efficient photocatalytic systems for reduction of CO₂.