Large-scale synthesis of high loading Co single-atom catalyst with efficient oxidase-like activity for the colorimetric detection of acid phosphatase

Single-atom catalysts (SACs) have shown broad application prospects in different area due to their maximum atomic utilization and excellent catalytic properties. However, how to realize large-scale synthesis of high loading SACs is still a problem for various application requirements. Herein, we report a novel strategy to synthesize Co single-atom catalyst (Co-SAC) by controllable releasing of Co atoms at high temperature, which can be effective to avoid the formation of Co nanoparticles. Particularly, the synthesized Co-SAC with Co content of 7.04 wt% contained exclusive single Co atoms coordinated Co-N4 active sites, demonstrated by inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray absorption spectroscopy (XAS). The obtained Co-SAC exhibited excellent intrinsic oxidase-like activity by catalyzing the dissolved oxygen to superoxide radicals. Based on the antioxidant of ascorbic acid (AA) and the enzymatic property of acid phosphatase (ACP), a colorimetric assay for AA and ACP was established by utilizing the oxidase-like activity of Co-SAC. The results indicated that the limit of detection (LOD) of AA and ACP was 1.31 μM and 0.08 U/L, respectively. Considering the large-scale synthetic method and its excellent catalytic property, this kind of Co-SAC would have a good prospect in biosensor fields.