Boosted Oxygen Vacancies and Lattice Oxygen Reactivity by Cobalt–Oxygen–Manganese Asymmetric Sites in Cryptomelane for Photoactivated Abatement of Volatile Organic Compounds

Catalytic activity is influenced by the local coordination environment. Cryptomelane-type octahedral molecular sieve (OMS-2) catalysts doped via K + substitution in the tunnels rarely exhibit photoactivation effects for volatile organic compound (VOC) abatement. We incorporated Co ions into the framework of OMS-2, not by replacing K + in the tunnels, thereby facilitating the formation of Co–O–Mn asymmetric sites. Engineering Co-incorporated OMS-2 efficiently promotes the generation of oxygen vacancies, the facile release of lattice oxygen, the reducibility of the catalysts, and a low formation energy of oxygen vacancies, as evidenced by experimental and theoretical results. Thus, the Co-OMS-2 catalysts exhibit excellent thermocatalytic activity for the oxidation of benzene. More importantly, Co–O–Mn asymmetric sites induce a photoactivation effect. A particularly marked enhancement of photothermocatalytic activity is observed over the Co-OMS-2 catalysts. Photoactivation further weakens the Mn–O bonds, promoting the release of lattice oxygen and increasing the concentration of oxygen vacancies. Furthermore, light irradiation induces distinct low-temperature shifts in both the H 2 consumption and O 2 release peaks relative to those observed in the dark. The reactivity of lattice oxygen is enhanced by a photoactivation effect. In situ DRIFTS provides further evidence for the synergy of Co–O–Mn asymmetric sites and photoactivation. This work proposes an effective approach to enhance photothermocatalytic VOC degradation through the rational design of asymmetric bimetallic sites.