Transforming Chemiluminescence from Flash to Glow by Breaking the Catalytic Limitation with a Medium‐Entropy Nanozyme

Abstract Intensive and persistent chemiluminescence (CL) emission is highly desired in biological imaging and is also a conundrum for most CL systems. Catalysts can efficiently improve the flash intensity but scarcely achieve persistent enhancement due to their catalytic limitation on CL reaction. Herein, a medium‐entropy (ME) nanozyme with trinuclear configuration and a classical Prussian blue analogue (PBA) structure was designed to break the catalytic limitation. The ME PBA showed favorable enhancement on both flash and persistent CL emission of luminol‐H 2 O 2 system due to the recycling generation of catalytic center Co(II) through quick electron transfer among metal sites within framework, which provided a relatively stable CL emission enhanced by over two orders of magnitude in 1 h, achieving the transformation of CL from flash to glow. The CL enhancement and active valence cycle mechanism via intrareticular electron transfer were revealed by both experiments and density functional theory calculations. A facile CL imaging method was proposed to evaluate the bacterial motility, which demonstrated the application potential of the ME PBA. This work offers a new avenue to transform CL from flash to glow by breaking the catalytic limitation of nanozymes, which will conveniently expand their application in bioanalysis.