Nitrogen, phosphorus co-doped hollow porous carbon microspheres as an oxidase-like electrochemical sensor for baicalin

The extraordinary properties and unique structure of porous carbon have rapidly turned it into a new favorite in the development and application of high-performance electrocatalytic sensors. Nitrogen, phosphorus co-doped hollow porous carbon microspheres (PRM-HPAs) as an oxidase-like electrocatalytic sensor for baicalin were successfully developed by two-stage activation using both 3-aminophenol and formaldehyde as carbon sources, phosphoric acid as an activator and dopant, and N-dehydroabietoyl-L-alanine as a soft-template. Low-temperature activation in air is the key to obtaining the hollow structure, and increases the content of oxygen-containing groups. High-temperature activation with phosphoric acid in nitrogen significantly increases the micropore content of PRM-HPA, and realizes phosphorus doping. The introduction of a soft-template can effectively prevent the agglomeration of carbon particles, and form uniformly dispersed hollow carbon microspheres. The PRM-HPA with a specific surface area of 1388 m2 g−1, pore volume of 0.69 m3 g−1, and pore size of 17 Å displays excellent electrocatalytic ability, oxidase-like characteristics, and an excellent electrochemical response of about 118-fold enhancement for baicalin in linear ranges of 0.03–7.99 μM with a low limit of detection of 4.3 nM. This work will open a new pathway for the preparation of co-doped hollow porous carbon microspheres and the application of renewable rosin resource.