Effective BPA degradation via atom-sharing Bi/Bi₄O₅Br₂:Yb³⁺,Tm^{3+ plasma heterojunctions with enhanced charge transfer and light absorption}

To achieve efficient degradation of organic pollutants, two critical objectives are enhancing photogenerated carrier separation and expanding the spectral response range. In this study, we synthesized atom-sharing Bi/Bi4O5Br2:Yb3+,Tm3+ (Bi/BYT) heterojunctions with surface plasmon resonance (SPR) effects and upconversion (UC) by employing self-sacrificial Bi4O5Br2:Yb3+,Tm3+ (BYT) fractions as a source of metallic Bi. Results revealed that the optimal Bi/BYT-2 catalyst exhibited the highest BPA degradation efficiency within 120 min, representing a significant 1.3-fold improvement over BYT alone. This outstanding catalytic performance can be attributed to the synergistic interplay between UC fluorescence, the unique SPR effect of Bi metal, and the atom-sharing heterojunction. These factors effectively broaden the spectral absorption range and significantly enhance the separation and utilization efficiency of photoinduced carriers. This study lays the groundwork for the development and design of novel atomic-level contact heterojunctions, offering insights into enhancing photocatalytic efficiency through plasmon resonance and UC fluorescence on non-precious metal surfaces.