Fluorescent carbon polymer nanomaterials driven by their important various applications are promising, however, their scalable usages are still hindered by the lack of facile and effective synthesis approaches. Herein, a rapid and facile approach is demonstrated for the preparation of fluorescent carbon polymer hollow spheres (CPHSs), which were synthesized by directly mixing concentrated sulfuric acid (H2SO4) and diethylenetriamine (DETA) at room temperature. Notably, both the solid powders and aqueous dispersion of CPHSs possess the fluorescence properties, similar with the reported carbon polymer dots. The formation of CPHSs could be attributed to the polymerization of DETA in the presence of H2SO4. The present strategy is universal and fluorescent nanomaterials could also be obtained by using hexamethylenetetramine or polyethylenepolayamine as precursors with the aid of concentrated H2SO4. Most importantly, the CPHSs possess peroxidase-like activity and can catalyze oxidation of 3,30,5,50-tetrame thylbenzidine (TMB) to its one-electron oxidation product, providing a new method for colorimetric detection of H2O2. (C) 2020 Elsevier Inc. All rights reserved.