Boosting the Catalase‐Like Activity of SAzymes via Facile Tuning of the Distances between Neighboring Atoms in Single‐Iron Sites

Abstract A nanozyme with neighboring single‐iron sites (Fe 2 ‐SAzyme) was introduced as a bioinspired catalase mimic, featuring excellent activity under varied conditions, twice as high as that of random Fe 1 ‐SAzyme and ultrahigh H 2 O 2 affinity as that of bioenzymes. Surprisingly, the interatomic spacing tuning between adjacent iron sites also suppressed the competitive peroxidase pathway, remarkably increasing the catalase/peroxidase selectivity up to ~6 times compared to Fe 1 ‐SAzyme. This dramatically switched the catalytic activity of Fe‐SAzymes from generating (i.e. Fe 1 ‐SAzymes, preferably mimicking peroxidase) to scavenging ROS (i.e. Fe 2 ‐SAzymes, dominantly mimicking catalase). Theoretical and experimental investigations suggested that the pairwise single‐iron sites may serve as a robust molecular tweezer to efficiently trap and decompose H 2 O 2 into O 2 , via cooperative hydrogen‐bonding induced end‐bridge adsorption. The versatile mechano‐assisted in situ MOF capsulation strategy enabled facile access to neighboring M 2 ‐SAzyme (M=Fe, Ir, Pt), even up to a 1000 grams scale, but with no obvious scale‐up effect for both structures and performances.