Construction of charge transfer chain in Bi12TiO20-Bi4Ti3O12/α-Bi2O3 composites to accelerate photogenerated charge separation

Photogenerated charge separation and transfer is one of the bottleneck steps in photocatalysis, and efficient charge separation strategies are strongly desired. Here, mimicking the electron transport chain in natural photosynthesis, we report the design and fabrication of a charge transfer chain using bismuth-based semiconductor as a proof-of-concept. In view of the thermodynamic energy band positions and structural similarity based on the density functional theory (DFT) analysis, heterostructured combination of α-Bi2O3, perovskite-like Bi4Ti3O12, and sillenite Bi12TiO20 was designed for fabrication of charge transfer chain. By tuning the molar ratio of Bi and Ti precursors, the Bi4Ti3O12 and Bi12TiO20 particles were formed on the surface of α-Bi2O3 by an in-situ transformation process, giving rise to Bi12TiO20-Bi4Ti3O12/α-Bi2O3 composites with charge transfer chain. We propose that the effective charge transfer is accomplished among α-Bi2O3, Bi12TiO20, and Bi4Ti3O12, which significantly improves the photogenerated charge separation and transfer, as indicated by photoluminescene, time-resolved photoluminescene, and electrochemical impedance spectra results. As expected, the Bi12TiO20-Bi4Ti3O12/α-Bi2O3 shows the superior photocatalytic activity for the degradation of environmental pollutants with high concentration. Even for the refractory pollutants like 4-chlorophenol, the optimal Bi12TiO20-Bi4Ti3O12/α-Bi2O3 composite shows 28 times higher than that of α-Bi2O3 for photocatalytic degradation, verifying the superiority of photogenerated charge transfer chain in photocatalysis. This work demonstrates the feasibility of the charge transfer chain strategy to boost the photogenerated charge separation, which is of great significance for designing energy and environmental-related materials in heterogonous photocatalysis. [Figure not available: see fulltext.].