Modulating the Selectivity of H ₂ O ₂ Activation via Interface Affinity-Dependent Metal–MOF Interactions in Pt-Based Nanozymes

Modulating the spatial position of active sites on MOF support offers a promising strategy for selective H 2 O 2 activation. However, the mechanism for regulating the selectivity of key intermediates in H 2 O 2 activation reactions is still unclear. Herein, we design two Pt-based nanozymes by integrating Au@Pt nanoparticles (NPs) into the external surface (Au@Pt/ZIF-8) and the pores (Au@Pt@ZIF-8) of ZIF-8, and systematically study the intrinsic relationship between the spatial position of metal NPs and the selectivity of H 2 O 2 activation. The experimental results indicate that the Au@Pt@ZIF-8 with more Pt–N bonds at the interface exhibits excellent catalytic activity, mainly producing singlet oxygen ( 1 O 2 ), while Au@Pt/ZIF-8 with fewer bonds is mainly dominated by hydroxyl radicals (•OH). Mechanism studies reveal that Au@Pt@ZIF-8 with more Pt–N bonds produces more electron-deficient Pt sites, significantly reducing the energy barrier of the critical step (*OH → *O), and promoting the generation of 1 O 2 . On the contrary, the Pt sites in Au@Pt/ZIF-8 have higher electron density, resulting in a higher energy barrier for the key step, and facilitating the accumulation of *OH. Importantly, a highly sensitive biosensor based on the Au@Pt@ZIF-8 nanozyme is successfully constructed for organophosphorus pesticide detection, with a limit of detection of 1 ng L –1 . This work not only elucidates the atomic-level mechanism by which spatial position regulates catalytic behavior via interfacial chemical bonding, but also provides new insights for the rational design of efficient H 2 O 2 activation.