Construction of Full-Spectrum-Response Bi₃O₄Br:Er³⁺@Bi₂O_{3- x} S-Scheme Heterojunction With [Bi─O] Tetrahedral Sharing by Integrated Upconversion and Photothermal Effect Toward Optimized Photocatalytic Performance

Designing and optimizing photocatalysts to maximize the use of sunlight and achieve fast charge transport remains a goal of photocatalysis technology. Herein, a full-spectrum-response Bi₃O₄Br:Er³⁺@Bi₂O_{3- x} core-shell S-scheme heterojunction is designed with [Bi─O] tetrahedral sharing using upconversion (UC) functionality, photothermal effects, and interfacial engineering. The UC function of Er³⁺ and plasmon resonance effect of Bi₂O_{3- x} greatly improves the utilization of sunlight. The equivalent layer structure of Bi₃O₄Br and Bi₂O_{3- x} facilitates the construction of high-quality S-scheme heterojunction interfaces with close atomic-level contact obtained from the [Bi─O] tetrahedral sharing and the resulting Bi₃O₄Br:Er³⁺@Bi₂O_{3- x} core-shell morphology, enabled efficient charge transfer. Furthermore, localized temperature increase, induced by photothermal effects, enhanced the chemical reaction kinetics. Benefiting from the distinctive construction, the Bi₃O₄Br:Er³⁺@Bi₂O_{3- x} heterojunctions exhibit excellent performance in the photocatalytic degradation of bisphenol A that is 2.40 times and 4.98 times greater than that of Bi₃O₄Br:Er³⁺ alone under full-spectrum light irradiation and near-infrared light irradiation, respectively. This work offers an innovative perspective for the design and fabrication of full-spectrum-response S-scheme heterojunction photocatalysts with efficient solar energy utilization based on high quality interfaces, UC functionality, and the photothermal effect.