Ion-Migration-Regulated NaCoPO4 Nanosheet as an Efficient Catalyst for Ultrasensitive Chemiluminescence Detection

Abstract For the luminol-H2O2 chemiluminescence (CL) system, developing high-performance nanocatalysts remains a major challenge. Inspired by the ion migration phenomenon in the electrode materials for ion batteries, we synthesized sodium cobalt phosphate nanosheets (NaCoPO4 NSs) with the hexagonal β-phase polymorphic structure consisting of tetrahedral Co (CoO4), in which Na+ occupied relatively open and low-coordination sites that facilitated ion migration. NaCoPO4 NSs achieve a CL enhancement factor of over 3000. Mechanistic studies revealed that the superior catalytic activity of NaCoPO4 NSs was mainly attributed to rapid Na+ ion migration during the catalytic reaction, which facilitated charge separation and transfer and further enhanced the decomposition of H2O2 into reactive oxygen species. Meanwhile, the high proportion of surface oxygen vacancies in NaCoPO4 NSs provided abundant catalytically active sites. Based on the quenching effect of l-ascorbic acid (ascorbic acid (AA)) on the luminol-H2O2 CL signal, a sensitive, rapid, and highly selective CL method for AA determination was developed, exhibiting a linear range from 100 to 5000 nM and a detection limit (limit of detection, S/N = 3) of 69.0 nM. Moreover, the proposed method was successfully applied to the accurate determination of AA in commercially available vitamin C beverage, with spiked recoveries ranging from 97.7% to 100.1%. This work highlights ion migration regulation as a promising strategy for designing high-performance nanocatalysts for CL analysis.