Ocean green tide derived hierarchical porous carbon with bi-enzyme mimic activities and their application for sensitive colorimetric and fluorescent biosensing

•Hierarchical porous carbon with both oxidase-like and peroxidase-like activities, was synthesized by a simple calcination of renewable ocean waste biomass.•The dual enzyme-like activities can be regulated by varying carbonized temperature.•The mechanism of oxidase mimics due to the 1O2 and O2−, while the peroxidase-like activity arising from hydroxyl radicals.•Sensitive colorimetric biosensor for acid phosphatase was explored based on the oxidase mimics.•Sensitive fluorometric sensing of glucose was explored based on glucose oxidase incorporation of the reaction between terephthalic acid and OH produced with the peroxidase-like activity.