Oxygen Vacancy-Mediated unraveling active species sources in BiO2-x Catalysts: The significance of lattice and molecular oxygen in catalytic reaction in aqueous solution

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 483; p. 149144
• Main Authors: Luo, Haopeng, Zhan, Chuanxiang, Uddin, Ahmed, Du, Heng, Jiang, Mingwei, Jiang, Fang, Chen, Huan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2024
• Subjects: Bismuth oxides (BiO2-x); CAWO under mild conditions; Lattice oxygen activation; Molecular oxygen filling; Oxygen vacancy; Bismuth oxides (BiO2-x); CAWO under mild conditions; Lattice oxygen activation; Oxygen vacancy; Molecular oxygen filling
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.149144

BiO2-x with varying vacancy contents was synthesized for mild-condition catalytic wet air oxidation (CWAO) to efficiently remove phenolic pollutants, and a cyclic process involving lattice oxygen reaction, oxygen vacancy formation, and dissolved oxygen supplementation emerged as the primary source of active species. [Display omitted] •BiO2-x with diverse vacancies made by adjusting hydrothermal time.•BiO2-x catalytic activity forms a volcano-like link with vacancy content.•Reactive oxygen species form via “lattice oxygen reaction-oxygen replenishment”.•Molecular oxygen filling markedly boosts catalyst stability. Catalytic wet air oxidation (CWAO), operating under mild conditions, presents a viable avenue for efficient organic pollutant elimination from wastewater. Metal oxide catalysts' CWAO activity depends on oxygen vacancies, but how these vacancies activate metal oxides to create reactive oxygen species (ROS) remains unclear. By modulating hydrothermal duration, we achieve variable BiO2-x vacancy levels, enabling proficient BPA degradation at approximately 60 °C. Outcomes reveal a pronounced correlation, akin to a volcanic trend, between oxygen vacancy abundance and BiO2-x catalytic activity. The principal active species originate from a cyclic process entailing lattice oxygen reaction, oxygen vacancy genesis, and dissolved oxygen supplementation. Thorough investigation, inclusive of radical trapping and electron paramagnetic resonance spectra (ESR), corroborates the pivotal role of lattice oxygen in generating OH, O2–, and 1O2. This investigation primarily aims to comprehensively explore how oxygen vacancies facilitate lattice oxygen activation and molecular oxygen filling in BiO2-x catalysts.