From electronically inert to active vacancies: Symmetry-breaking Co–Ov–Mo motifs stabilized by quenching for ultrafast non-radical peroxymonosulfate activation

Vacancy electronic quality, not quantity, governs catalytic performance. • Co-doping and quenching construct asymmetric Co–Ov–Mo motifs, transforming inert deep traps into active shallow donors. • CMO-Q activates PMS through a dual non-radical pathway. The electronic structure characteristics of oxygen vacancies (O v ) - rather than their quantity - are the fundamental factors determining peroxymonosulfate (PMS) activation. This study proposes a strategy of cobalt doping and controllable quenching to precisely construct two types of O v configurations with distinct electronic properties in MoO 3 : the symmetrical Mo–O v –Mo coordination structure in MoO 3 -Q and the asymmetrical Co–O v –Mo coordination structure in CMO-Q. Comprehensive multimodal characterizations confirm that although MoO 3 -Q has the highest O v concentration (39.78%) and the strongest EPR signal, the significantly broadened tail feature in its valence band XPS spectrum clearly indicates that the vacancies exist in the form of deep-level trap states, making it difficult for the captured charges to participate in subsequent interfacial reactions, thus presenting electronic inertness. In contrast, cobalt doping plays a directional anchoring role in the lattice, guiding the vacancies to preferentially form in the Co-adjacent coordination environment. The constructed asymmetrical Co–O v –Mo structure induces an internal polarization electric field due to the difference in electronegativity between Co 2+ and Mo 6+ , forming a shallow donor state with electron-donating function, thereby endowing the vacancies with intrinsic electronic activity. The electrochemical tests quantitatively reveal the essential differences in interfacial charge transfer kinetics between the two: CMO-Q exhibits the largest open-circuit potential shift (0.59  V ) and the smallest peak potential difference (ΔE = 0.13  V ), while MoO 3 -Q shows the smallest shift (0.47  V ) and the largest ΔE (0.26  V ). Further normalization by the electrochemically active surface area (ECSA) highlights the intrinsic activity difference: the k obs /C dl of CMO-Q reaches 6.18 min −1 ·cm 2 ·mF −1 , which is ten times higher than that of MoO 3 -Q (0.62 min −1 ·cm 2 ·mF −1 ). This work establishes vacancy quality over quantity as the design principle for high-performance catalysts.