Single‐atom catalysts (SACs) have attracted extensive attention in the catalysis field because of their remarkable catalytic activity, gratifying stability, excellent selectivity, and 100% atom utilization. With atomically dispersed metal active sites, Fe‐N‐C SACs can mimic oxidase by activating O2 into reactive oxygen species, O2−• radicals. Taking advantages of this property, single‐atom nanozymes (SAzymes) can become a great impetus to develop novel biosensors. Herein, the performance of Fe‐N‐C SACs as oxidase‐like nanozymes is explored. Besides, the Fe‐N‐C SAzymes are applied in biosensor areas to evaluate the activity of acetylcholinesterase based on the inhibition toward nanozyme activity by thiols. Moreover, this SAzymes‐based biosensor is further used for monitoring the amounts of organophosphorus compounds.

Single-atom nanozymes (SAzymes), as novel nanozymes with atomically dispersed active sites, are of great importance in the development of nanozymes for their high catalytic activities, the maximum utilization efficiency of metal atoms, and the simple model of active sites. Herein, the peroxidase-like SAzymes with high-concentration Cu sites on carbon nanosheets (Cu–N–C) were synthesized through a salt-template strategy. With the densely distributed active Cu atoms (∼5.1 wt %), the Cu–N–C SAzymes exhibit remarkable activity to mimic natural peroxidase. Integrating Cu–N–C SAzymes with natural acetylcholinesterase and choline oxidase, three-enzyme-based cascade reaction system was constructed for the colorimetric detection of acetylcholine and organophosphorus pesticides. This work not only provides a strategy to synthesize SAzymes with abundant active sites but also gives some new insights for robust nanozyme biosensing systems.

Single-atom alloys (SAAs) have ignited a surge of unprecedented interest as the advanced nanomaterials and opened many opportunities for wide applications. Herein, 3D porous aerogels comprising ionic liquid (IL) functionalized PdBi SAA building blocks with atomically dispersed Bi on Pd nanowires (IL/ Pd 50 Bi 1 ) are synthesized with accelerated gelation kinetics, which could serve as high-efficiency electrocatalysts for ethanol oxidation reaction (EOR). Benefiting from the unique structures of aerogels including synergistic effects of PdBi SAA nanowire networks and interface engineering, the optimized IL/Pd 50 Bi 1 aerogels display a nearly fourfold enhancement in mass activity and boosted stability for EOR compared to commercial Pd/C. Density functional theory calculations further demonstrate that isolated Bi atoms on Pd nanowire networks decrease the energy barrier of the rate-determining step, resulting in excellent electrocatalytic activity for EOR. This work provides a promising method for developing efficient SAA catalysts for fuel electrooxidation.

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