Engineering synergistic VO-Co3+ pairs in CoOOH nanosheets for highly efficient and selective catalytic ozonation of CVOCs.

The catalytic activation of O3 on solid surfaces generates a spectrum of reactive oxygen species (ROS) with vastly different oxidative power. A central challenge lies in identifying surface sites that selectively produce highly oxidizing radicals over less reactive species, and in harnessing these potent ROS for efficient pollutant destruction. Here, we uncover a surface site dichotomy in cobalt oxides that governs O3 activation selectivity in the photo-enhanced catalytic ozonation of dichloromethane (DCM). Using CoOOH, Co3O4, and CoO as a model system, we demonstrate that O3 preferentially adsorbs at VO, triggering electron transfer from the neighboring Co3+ to the adsorbed O3. This electronic redistribution channels O3 decomposition exclusively through a radical pathway (•O/•O2-). In sharp contrast, Co2+-rich surfaces lacking this VO-Co3+ synergy favor an energy-transfer pathway yielding 1O2. The radical pathway confers a 3-fold higher DCM mineralization efficiency and a 34.7% lower O3 consumption. The advantage of CoOOH in selective ROS generation applies equally to alkanes and aromatic compounds. This work establishes that pathway-selective activation reduces the O3 demand, which in turn lowers the energy required for its generation.