The single‐atom enzyme (SAE) is a novel type of nanozyme that exhibits extraordinary catalytic activity. Here, we constructed a PEGylated manganese‐based SAE (Mn/PSAE) by coordination of single‐atom manganese to nitrogen atoms in hollow zeolitic imidazolate frameworks. Mn/PSAE catalyzes the conversion of cellular H2O2 to .OH through a Fenton‐like reaction; it also promotes the decomposition of H2O2 to O2 and continuously catalyzes the conversion of O2 to cytotoxic .O2− via oxidase‐like activity. The catalytic activity of Mn/PSAE is more pronounced in the weak acidic tumor environment; therefore, these cascade reactions enable the sufficient generation of reactive oxygen species (ROS) and effectively kill tumor cells. The prominent photothermal conversion property of the amorphous carbon can be utilized for photothermal therapy. Hence, Mn/PSAE exhibits significant therapeutic efficacy through tumor microenvironment stimulated generation of multiple ROS and photothermal activity.
The development of atomically precise dinuclear heterogeneous catalysts is promising to achieve efficient catalytic performance and is also helpful to the atomic-level understanding on the synergy mechanism under reaction conditions. Here, we report a Ni 2 (dppm) 2 Cl 3 dinuclear-cluster-derived strategy to a uniform atomically precise Ni 2 site, consisting of two Ni 1 −N 4 moieties shared with two nitrogen atoms, anchored on a N-doped carbon. By using operando synchrotron X-ray absorption spectroscopy, we identify the dynamically catalytic dinuclear Ni 2 structure under electrochemical CO 2 reduction reaction, revealing an oxygen-bridge adsorption on the Ni 2 −N 6 site to form an O−Ni 2 −N 6 structure with enhanced Ni−Ni interaction. Theoretical simulations demonstrate that the key O−Ni 2 −N 6 structure can significantly lower the energy barrier for CO 2 activation. As a result, the dinuclear Ni 2 catalyst exhibits >94% Faradaic efficiency for efficient carbon monoxide production. This work provides bottom-up target synthesis approaches and evidences the identity of dinuclear sites active toward catalytic reactions.
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