Coordination Number Regulation of Molybdenum Single-Atom Nanozyme Peroxidase-like Specificity

Nanozymes are promising alternatives to natural enzymes, but their use remains limited owing to poor specificity. Overcoming this and controlling the targeted enzyme-like performance of traditional nanozymes is extremely challenging due to the intrinsic structural complexity of these systems. We report theoretical design and experimental realization of a series of heterogeneous molybdenum single-atom nanozymes (named MoSA–Nx–C), wherein we find that the peroxidase-like specificity is well regulated by the coordination numbers of single Mo sites. The resulting MoSA–N3–C catalyst shows exclusive peroxidase-like behavior. It achieves this behavior via a homolytic pathway, whereas MoSA–N2–C and MoSA–N4–C catalysts have a different heterolytic pathway. The mechanism of this coordination-number-dependent enzymatic specificity is attributed to geometrical structure differences and orientation relationships of the frontier molecular orbitals toward these MoSA–Nx–C peroxidase mimics. This study demonstrates the rational design of peroxidase-specific nanozymes and precise regulation of their enzymatic properties.