Frustrated Lewis Pair-Induced Pre-Adsorbed Oxygen Coupled With Reactant Availability as a Design Strategy for High-Performance Single-Atom Nanozymes.

Single-atom nanozymes (SANs) have recently been recognized as a promising artificial counterpart to natural enzymes. Nevertheless, their catalytic performance remains hindered by insufficient intrinsic activity, which stems from the substantial energy barriers associated with substrate activation and poor mass transport, limiting reactant availability. To address this, we designed a frustrated Lewis pair (FLP)-based Fe-N-C single-atom nanozyme (FLP-Fe-N-C SAzyme) with enriched pyridinic N vacancy defects to enhance oxygen adsorption for the construction of high-performance oxidase mimics. Density functional theory calculations demonstrate that the FLP structure, with Fe as Lewis acid sites and adjacent F regions as Lewis base sites, synergistically promotes oxygen dissociation and induces a pre-adsorbed oxygen atom beside the catalytic center. Such a newly formed structure induced by the FLP sites showed an optimized electronic and geometric structure of the catalytic center, lowering the energy barrier. In addition, the abundant pyridinic-N vacancies induced an enhanced oxygen adsorption, increasing the local oxygen concentration and thereby accelerating reactant availability. Hence, the FLP-Fe-N-C SAzyme remarkably enhances the intrinsic activity of the oxidase-mimicking SANs, achieving a significantly lower Km value than conventional Fe-N-C SANs.