In-plane multiple heterogeneous Bi4O5I2/β-Bi2O3 nanoflowers with S-type scheme for efficient photocatalytic CO2 conversion

The assembly of heterogeneous photocatalysts with unique structures by 2D heterojunctions is an advanced strategy for efficient solar energy conversion. However, heterogeneous photocatalysts constructed from 2D materials will suffer from high photogenerated charge recombination and low light absorption due to the arbitrary stacking and weak bonding of lamellae. Here, flower-like Bi4O5I2/β-Bi2O3 (FL-Bi4O5I2/β-Bi2O3) heterojunctions are developed in situ using FL-δ-Bi2O3 as the starting material. It is noteworthy that the basic compositional form of the material was well maintained throughout the synthesis. Besides, due to the random reaction of iodide ions with the exposed surface of δ-Bi2O3, multiple heterogeneous regions are displayed on the basic lamellar units constituting the Bi4O5I2/β-Bi2O3 nanoflowers. Theoretical and experimental results reveal that FL-Bi4O5I2/δ-Bi2O3 possesses not only improved photogenerated carrier separation, enhanced light harvesting, but also considerable CO2 adsorption. Importantly, FL-Bi4O5I2/β-Bi2O3 achieves S-scheme CO2 conversion due to its reasonable energy band structure, and with the CO generation rate of up to 31.74 μmol g−1h−1 under simulated sunlight.