Single-atom nanozymes with axial ligand-induced self-adaptive conformation in alkaline medium boost chemiluminescence

Mimicking the structure of natural enzymes for designing advanced alternatives provides great opportunities to address the bottleneck of enzyme-involved chemiluminescence (CL). Herein, according to theoretical calculations, we found that an endogenous axial ligand of M-N-C single-atom nanozymes (SAzymes), originating from OH⁻ spontaneously bonding to the metal center in an alkaline medium, can self-adaptively change its strength to facilitate intermediate steps. Furthermore, the lowest energy barrier of the rate-determining step and the strongest affinity and fastest electron transfer with luminol anion endow Co-N-C with the highest peroxidase-like activity. Guided by the theoretical calculations, a series of M-N-C SAzymes (M=Fe, Co, Ni) were synthesized to boost CL, where Co-N-C SAzymes with superior catalytic activity and high selective generation of O₂^•− were validated. As a proof-of-concept, Co-N-C SAzymes were employed for sensitive detection of acetylcholinesterase and organophosphorus pesticide. [Figure not available: see fulltext.]