Stabilizing Ru-Based Catalysts against Bromine Poisoning through Ru–O Covalency Regulation for Durable Brominated Volatile Organic Compound Oxidation

Catalytic oxidation is an effective approach for brominated volatile organic compound (BVOC) abatement to reduce its negative environmental impacts, yet its application is severely hindered by catalyst bromine poisoning. The unique bromine-induced lattice oxygen substitution may constitute a key deactivation pathway in catalytic BVOC degradation, necessitating the stabilization of lattice oxygen as the pivotal challenge. Herein, we report an Sn-mediated Ru-O covalency regulation strategy to stabilize the lattice oxygen of RuO₂ against bromine poisoning. The optimized RuSn_0.25/TiO₂ achieves exceptional stability (>200 h) in dibromomethane oxidation, with <0.2% activity loss at 240000 mL·g^-1·h^-1, outperforming Ru/TiO₂ (∼20% loss). The Ru-O covalency and lattice oxygen stability against bromine poisoning were systematically investigated. Multiple characterizations confirm the weakened Ru-O covalency, while transient CO oxidation reveals suppressed lattice oxygen depletion (5% vs 60% in pristine Ru/TiO₂ after bromination). Theoretical calculations reveal that Sn doping lowers the O 2<i>p</i> band center, reducing Ru 4<i>d</i> and O 2<i>p</i> orbital overlap and thus weakening Ru-O covalency. As a result, the lattice oxygen was stabilized and protected from Br substitution due to a higher energy barrier. This study confirms the crucial influence of Ru-O covalency in stabilizing lattice oxygen against bromine poisoning, providing fundamental guidance for environmental catalytic reactions involving lattice oxygen and/or bromine species.