Construction of CeO2/Bi2O3 heterojunction photocatalyst for the efficient degradation of organic dyes

Abstract

The technological limitations associated with both the substantial treatment costs of the traditional Fenton method and the prolonged degradation cycles of biological methods were addressed. Novel CeO₂/Bi₂O₃ heterojunction photocatalysts were developed, and the photocatalytic mechanism by which the Type-II heterojunctions suppress electron-hole recombination through interfacial charge transfer was elucidated. The CeO₂/Bi₂O₃ microspheres (particle size: 200–300 nm), synthesized via high-temperature pyrolysis, exhibited a specific surface area of 23.98 m²/g and an average pore size of 16.47 nm. The degradation efficiencies for tetracycline (TC) and methylene blue (MB) reached 79.93 % and 89.81 %, respectively, which were significantly higher than those of pure CeO₂ and Bi₂O₃. The enhanced photocatalytic performance originates from the Type-II heterojunction energy band alignment and interfacial charge separation, which synergistically suppress electron-hole recombination. Liquid chromatography-mass spectrometry (LC-MS) and radical trapping experiments elucidated the photocatalytic degradation mechanism of MB dyes. Biotoxicity tests showed significantly reduced toxicity of degradation products, and the mineralization process yielded environmentally benign mineralized products. Furthermore, the CeO₂/Bi₂O₃ heterojunction exhibited remarkable photoelectric activity, achieving a photocurrent density of 253 μA/cm² and an open-circuit photovoltage of −0.04 V. These enhancements were attributed to its strong visible-light absorption and low interfacial charge-transfer resistance. This study provides a promising approach for efficient and low-cost treatment of organic pollutants, offering new insights into the design of heterojunction photocatalysts.