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

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-N-4 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 O-2 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.

Automated summary

This study demonstrates a regulatory mechanism based on the electron filling and orbital energies of metal active centers and provides a rational catalyst design strategy for achieving ultrahigh H2O2-decomposition activity. Among the investigated platinum-group-metal active centers, Ir-N-4 with partially occupied d(x2-y2) and d(xz) orbitals and the highest d-band center shows the strongest interaction with H2O2 and the lowest energy barrier for its decomposition. The single-atom Ir catalyst (Ir-NC) exhibits an ultrahigh H2O2-decomposition capacity, which is 1614 times higher than that of natural catalase, and surface-adsorbed atomic oxygen is identified as the key intermediate for O2 generation.