Single‐Atom Catalysts with Ultrahigh Catalase‐Like Activity Through Electron Filling and Orbital Energy Regulation

Abstract Developing nanomaterials with high H₂O₂‐decomposition capacity to replace traditional biological enzymes is of great importance in environmental, semiconductor, and medical fields. However, a lack of understanding of the reaction mechanism leads to aimless catalyst design and limits further improvement of catalytic activity. Here, the regulatory mechanism based on the electron filling and orbital energies of the metal active centers is demonstrated and a rational catalyst design strategy is provided to achieve ultrahigh H₂O₂‐decomposition activity. Among the five platinum‐group‐metal active centers investigated in this study, the Ir–N₄ with partially occupied d_x2−y2 and d_xz orbitals and the highest d‐band center most strongly interacts with H₂O₂, and show the lowest energy barrier for H₂O₂ decomposition. As expected, the single‐atom Ir catalyst (Ir‐NC) shows an ultrahigh H₂O₂‐decomposition capacity, which is 1614‐times higher than that of natural catalase. Surface‐adsorbed atomic oxygen is observed and verified to be the key intermediate for O₂ generation. Biocompatible Ir‐NC is effective in scavenging intracellular reactive oxygen species and holds great potential for clinical therapeutics associated with oxidative stress. This study advances the mechanistic understanding of H₂O₂ decomposition and provides useful guidance for rational design of high‐performance artificial nanozymes.