Constructing TiO2@Bi2O3 multi-heterojunction hollow structure for enhanced visible-light photocatalytic performance

Combining heterojunction with advanced structures is a promising tool to enhance the photoelectrochemical performance of semiconductor photocatalysts for environmental remediation. Herein, a novel multi-heterojunction TiO2@Bi2O3 (MHTB) hollow photocatalyst is successfully constructed by loading Bi2O3 nanoparticles on the surface of inner TiO2 and outside of TiO2 shell. Photoelectrochemical characterizations show that the formation of multiple heterojunctions at the TiO2@Bi2O3 interfaces facilitates faster separation and transfer of photoinduced charge carriers than that of conventionally reported p-n heterojunction photocatalysts. Because of the separated two layers of Bi2O3 and unique hollow structure, the photocatalytic performance of MHTB is significantly improved, leading to excellent photo-degradation rate constant (k = 0.0165 min−1) for the degradation of levofloxacin, which approaches 1.5-fold and 2.6-fold increase than that of TiO2@Bi2O3@TiO2 (n-p-n heterojunction) and TiO2@Bi2O3 (n-p heterojunction), respectively. Notably, the MHTB photocatalyst exhibits an excellent anti-interference capability for the interference of environmental factors. Moreover, the photocatalytic activity, crystal structure, and bonding energy of MHTB photocatalyst remain unchanged after being used several times, indicating an excellent stability. Therefore, this finding opens a new door to develop highly active photocatalysts with multiple heterojunctions for efficient pollutant removal and environmental remediation.