Enhancement of Charge Separation and NIR Light Harvesting through Construction of 2D-2D Bi4O5I2/BiOBr:Yb3+, Er3+ Z-Scheme Heterojunctions for Improved Full-Spectrum Photocatalytic Performance

Developing full-spectrum photocatalysts with simultaneous broadband light absorption, excellent charge separation, and high redox capabilities is becoming increasingly significant. Herein, inspired by the similarities in crystalline structures and compositions, a unique 2D-2D Bi4O5I2/BiOBr:Yb3+,Er3+ (BI-BYE) Z-scheme heterojunction with upconversion (UC) functionality is successfully designed and fabricated. The co-doped Yb3+ and Er3+ harvest near-infrared (NIR) light and then convert it into visible light via the UC function, expanding the optical response range of the photocatalytic system. The intimate 2D-2D interface contact provides more charge migration channels and enhances the Forster resonant energy transfer of BI-BYE, leading to significantly improved NIR light utilization efficiency. Density functional theory (DFT) calculations and experimental results confirm that the Z-scheme heterojunction is formed and that this heterojunction endows the BI-BYE heterostructure with high charge separation and strong redox capability. Benefit from these synergies, the optimized 75BI-25BYE heterostructure exhibits the highest photocatalytic performance for Bisphenol A (BPA) degradation under full-spectrum and NIR light irradiation, outperforming BYE by 6.0 and 5.3 times, respectively. This work paves an effective approach for designing highly efficient full-spectrum responsive Z-scheme heterojunction photocatalysts with UC function.

Automated summary

Developing full-spectrum photocatalysts with simultaneous broadband light absorption, excellent charge separation, and high redox capabilities is increasingly important. In this study, a unique 2D-2D Bi4O5I2/BiOBr:Yb3+,Er3+ (BI-BYE) Z-scheme heterojunction with upconversion functionality was successfully designed and fabricated. The optimized BI-BYE heterostructure exhibited superior photocatalytic performance for Bisphenol A degradation under full-spectrum and near-infrared light irradiation, outperforming the reference material BYE by 6.0 and 5.3 times, respectively.