Atomically dispersed nanozymes have garnered immense attention within the biomedical field, while precisely designing these nanozymes and elucidating their intricate structure-performance relationships of their structures and antibacterial performance remain the formidable challenges. Herein, we fabricated defect-rich graphene supported layered Ir cluster nanozymes for antibacterial applications. Steady-state kinetic experiments revealed that the layered Ir clusters exhibited the higher catalytic efficiency of 1.16 mM⁻¹·s⁻¹ with 3,3',5,5'-tetramethylbenzidine (TMB) and 0.18 mM⁻¹·s⁻¹ with H₂O₂, compared to Ir nanoparticle (0.55 and 0.1 mM⁻¹·s⁻¹) and the atomically dispersed Ir single-atom nanozyme (SAzyme) (0.3 and 0.039 mM⁻¹·s⁻¹) and other previously reported single-atom nanozymes. Moreover, both experimental results and density functional theory studies disclosed that the layered Ir clusters exhibited the enhanced ability to facilitate the conversion of hydrogen peroxide into hydroxyl free radicals, signifying the higher catalytic efficiency than that on Ir nanoparticles and Ir single-atoms. Notably, the Ir cluster nanozyme with robust peroxidase-like activity had 100% antimicrobial rate against E. coli and S. aureus, underscoring its potential applications in antibacterial fields.

The pursuit of energy conservation and environmental protection has always been a hot topic in the catalytic fields, which is inseparable from the rational designing of efficient catalysts and an in-depth understanding of the catalytic reaction mechanism. In this work, fully-exposed Pt clusters were fabricated on the atomically dispersed Sn decorated nanodiamond/graphene (Sn-ND@G) hybrid support and employed for direct dehydrogenation (DDH) of ethylbenzene (EB) to styrene (ST). The detailed structural characterizations revealed the fully-exposed Pt clusters were stabilized on Sn-ND@G, assisted by the spatial separation of atomically dispersed Sn species. The as-prepared Pt/Sn-ND@G catalyst showed enhanced ST yield (136.2 mol_EB·mol_Pt⁻¹·h⁻¹ EB conversion rate and 99.7% ST selectivity) and robust long-term stability at 500 °C for the EB DDH reaction, compared with the traditional ND@G supported Pt nanoparticle catalyst (Pt/ND@G). The ST prefers to desorb from the fully-exposed Pt clusters, resulting in the enhanced DDH catalytic performance of the Pt/Sn-ND@G catalyst. The present work paves a new way for designing highly dispersed and stable supported metal catalysts for DDH reactions.