The traditional luminol–H2O2 electrochemiluminescence (ECL) sensing platform suffers from self‐decomposition of H2O2 at room temperature, hampering its application for quantitative analysis. In this work, for the first time we employ iron single‐atom catalysts (Fe‐N‐C SACs) as an advanced co‐reactant accelerator to directly reduce the dissolved oxygen (O2) to reactive oxygen species (ROS). Owing to the unique electronic structure and catalytic activity of Fe‐N‐C SACs, large amounts of ROS are efficiently produced, which then react with the luminol anion radical and significantly amplify the luminol ECL emission. Under the optimum conditions, a Fe‐N‐C SACs–luminol ECL sensor for antioxidant capacity measurement was developed with a good linear range from 0.8 μm to 1.0 mm of Trolox.

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.

Multiple enzymes‐induced biological cascade catalysis guides efficient and selective substrate transformations in vivo. The biomimetic cascade systems, as ingenious strategies for signal transduction and amplification, have a wide range of applications in biosensing. However, the fragile nature of enzymes greatly limits their wide applications. In this regard, metal–organic frameworks (MOFs) with porous structures, unique nano/microenvironments, and good biocompatibility have been skillfully used as carriers to immobilize enzymes for shielding them against hash surroundings and improving the catalytic efficiency. For another, nanomaterials with enzyme‐like properties and brilliant stabilities (nanozymes), have been widely applied to ameliorate the low stability of the enzymes. Inheriting the abovementioned merits of MOFs, the performances of MOFs‐immboilized nanozymes could be significantly enhanced. Furthermore, in addition to carriers, some MOFs can also serve as nanozymes, expanding their applications in cascade systems. Herein, recent advances in the fabrication of efficient MOFs‐involving enzymes/nanozymes cascade systems and biosensing applications are highlighted. Integrating diversified signal output modes, including colorimetry, electrochemistry, fluorescence, chemiluminescence, and surface‐enhanced Raman scattering, sensitive detection of various targets (including biological molecules, environmental pollutants, enzyme activities, and so on) are realized. Finally, challenges and opportunities about further constructions and applications of MOFs‐involving cascade reaction systems are briefly put forward.

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Luminol-dissolved O2 electrochemiluminescence (ECL)-sensing platforms have been widely developed for sensitive and reliable detection, while their actual ECL mechanisms are still in controversy due to the involved multiple reactive oxygen species (ROS). Different from the structural complexity of nanomaterials, well-defined single-atom catalysts (SACs) as coreaction accelerators will provide great prospects for investigating the ECL mechanism at the atomic level. Herein, two carbon-supported nickel SACs with the active centers of Ni–N4 (Ni–N4/C) and Ni–N2O2 (Ni–N2O2/C) were synthesized as efficient coreaction accelerators to enhance the ECL signals of a luminol-dissolved O2 system. By modulating the surrounding environment of the center metal atoms, their corresponding oxygen reduction behaviors can be well controlled to selectively produce intermediate ROS, giving a great chance to study the following ECL process. According to the experimental and calculated results, the superoxide radical (O2 •–) acts as the main radical for the ECL reaction and the Ni–N4/C catalyst with the four-electron pathway to activate dissolved O2 is preferential to enhance ECL emission.