Synergistic enhancement of photocatalytic methylene blue degradation by In ₂ O ₃ /Bi ₂ O ₃ heterojunction toward environmental remediation

The development of efficient heterojunction photocatalysts for environmental remediation remains challenging due to rapid charge recombination and insufficient active sites in conventional single-component systems. This study developed a facile wet impregnation method of In₂O₃-Bi₂O₃heterojunction photocatalysts with tunable compositions for enhanced visible-light-driven photocatalytic degradation. By systematically modulating the In₂O₃to Bi₂O₃ratio, the optical properties, electronic structures, and photocatalytic activities of the materials can be precisely manipulated. The optimized 30% In₂O₃-Bi₂O₃heterojunction exhibited a remarkable methylene blue degradation efficiency of 93% under visible light, outperforming pure In₂O₃and Bi₂O₃. Mechanistic studies revealed that the type-II band alignment facilitated spatial separation of photogenerated electron-hole pairs and enhanced redox capacity. Furthermore, the surface oxygen vacancies of materials introduced by the alkaline etching method were found to significantly enhance the availability of active sites and optimize the band structure, contributing to a notable increase in photocatalytic activity. These heterojunctions also exhibited remarkable stability, retaining over 90% degradation efficiency after five consecutive cycles. This study indicates the significant potential of In₂O₃-Bi₂O₃heterojunctions for enhancing environmental remediation and solar energy conversion initiatives, and also introduces a straightforward and effective synthesis approach to photocatalyst design by composition regulation and defect engineering.