Multiple defects construction of Co loading on Ni foam to activate water for promoting catalytic ozonation of dichloromethane.

Catalytic ozonation of chlorinated volatile organic compounds (Cl-VOCs) still faces with obstacles of water poisoning and byproducts formation. This work successfully synthesizes a Co-based monolithic catalyst with multiple defects construction that could activate water to promote dichloromethane (DCM) conversion and mineralization by catalytic ozonation at 120 °C. CO(NH2)2 and NH4F firstly create Ni defects to provide more adhesion sites, while they further contributed to crystallization and orientated growth of CoOx with a morphology of crowded nanoneedles, respectively, as well as etching Co defects and oxygen vacancies. Co-NUF-6 exhibited a DCM conversion of up to 88 % at a O3/DCM of 10.0, and 3 vol% water elevated it to 98 % with approximately three times reduction of polychlorinated byproducts. CoOx with abundant defects exhibited excellent water-activating effect to generate abundant O2- (superoxide) and O22- (peroxide), which replenished lattice oxygen and facilitated the production of more active hydroxyl groups from O3 hydroxylation, contributing to better DCM conversion and mineralization. This work transits low-temperature water poisoning to water activating and eliminated toxic polychlorinated byproducts by developing the monolithic catalyst with multiple defects for efficient elimination of DCM, which has application potential towards practical waste gas purification and provides guidance for future water-activating catalyst design.