A cobalt-vacant Co3O4 as a stable catalyst for room-temperature decomposition of ozone in humid air

Conventionally ozone-decomposition catalysts such as MnO2 face the gradual deactivation due to occupation of reactive site, i.e., oxygen vacancy by intermediates like O22- or ubiquitous water vapor in air. Herein, we synthesized a Co2+-vacant Co3O4 (Co3−xO4) with dominant exposure of (110) facets, it maintained superior efficiency of 98% in decomposing 100 ppm ozone over 180 h under the space velocity of 1200 L/g·h at 25 ℃ and relative humidity (RH) of 50%, well beyond the performance of any reported metal oxides catalysts. Especially, it kept stable efficiency even under RH 90% and ultrahigh space velocity of 6000 L/g·h. A new ozone decomposition mechanism under humid conditions is revealed, i.e., the Co2+ vacancy significantly promotes O3 adsorption and the hydroxylation of coordination-unsaturated oxygen (CUO), and Co3+ work together with surface OH group to decompose ozone avoiding the deactivation. This study demonstrates a new way, i.e., creating metal vacancy rather than oxygen vacancy to design stable and efficient catalysts for ozone decomposition under humid conditions. [Display omitted] •A Co2+-vacant Co3O4 with dominant exposure of (110) facet was synthesized.•Superior ozone decomposition stability even under RH 90% and 6000 L/g·h.•Co2+ vacancy enhances preferential adsorption of ozone over water on Co3+ site.•Coordination-unsaturated oxygen hydroxylated to participate in ozone decomposition.•Co3+ together with OH decomposes ozone to avoid deactivation due to water vapor.