sp‐Hybridized Carbon Modulates the Spin States of Ir Nanozyme for Efficient Oxygen Activation

ABSTRACT The kinetics of oxidase‐like (OXD‐like) nanozymes are significantly influenced by the electronic configuration of their active sites. In this study, a nanozyme that features unique electronic interactions was created by in situ construction of iridium nanoparticles on graphdiyne‐coated carbon nanotube (Ir/GDY/CNT). This configuration enables efficient and specific oxygen activation through a spin‐state modulation mechanism. The incorporation of sp‐hybridized carbon (sp‐C) facilitates a transition in the electronic structure of the Ir sites from low‐spin to high‐spin states via electronic metal‐support interactions. This enhances the adsorption strength and electron transfer between the Ir sites and reactants/intermediates, leading to an improved OXD‐like activity. The Ir/GDY/CNT nanozyme demonstrates a 6.2‐fold enhancement in OXD‐like activity compared to pristine iridium nanoparticles, and a 2.5‐fold improvement over Ir/CNT. Capitalizing on this improved catalytic performance, a colorimetric sensor was developed for the detection of organophosphorus pesticides. The sensor exhibits a wide linear range (0.1–1200 ng mL −1 ) and ultralow detection limit (0.03 ng mL −1 ), outperforming previously reported systems. This work establishes a generalizable strategy for developing high‐performance OXD‐like nanozymes through spintronics‐level engineering, which presents significant potential for environmental and diagnostic applications.