Axial oxygen ligand engineering enhances catalytic selectivity of single-atom nanozymes for bubble-propelled nanomotors

Regulating the selectivity of single-atom nanozymes (SAzymes) through axial ligand engineering is highly significant yet challenging, especially for heme-like M–N4 structured SAzymes, which exhibit powerful enzyme-like catalytic efficiency and broad applicability. Inspired by natural catalases bearing proximal tyrosine ligands and capable of selective hydrogen peroxide decomposition, we synthesized FeNSC–O SAzymes featuring axial oxygen coordination stabilized by planar sulfur doping, achieving a catalase/peroxidase–like selectivity up to 6.5 times greater than that of planar oxygen-doped FeNC–O SAzymes. Density functional theory (DFT) calculations reveal that the axial oxygen coordination weakens Fe–intermediate interactions, suppressing the peroxidatic pathway and enhancing catalase-like specificity. Furthermore, encapsulating FeNSC–O within a nanoreactor enabled the successful construction of bubble-propelled nanomotors capable of efficient oxygen generation for self-propulsion, demonstrating promising potential for targeted therapy and precision medicine.