Mn3O4/N‐Doped Graphite Catalysts from Wastewater for the Degradation of Methylene Blue

Abstract The accelerating research interest in graphene involving the use of Hummers method has generated non‐negligible amount of wastewater containing residual graphite as well as Mn 2+ . In this paper, we report the first example of using this wastewater as precursor to prepare Mn 3 O 4 /N‐doped graphite (NG) composites through a facile solvothermal process. The mass fraction of Mn 3 O 4 in the composites was manipulated by adding various amounts of extra Mn 2+ . The conversion of Mn 2+ to Mn 3 O 4 nanoparticles and the N atoms doping were achieved by adding hydrazine hydrate and ammonia into the system. The as‐obtained Mn 3 O 4 /NG composites were well characterized by SEM, TEM, EDS, Raman, XPS, TGA, XRD and N 2 adsorption–desorption experiments and showed excellent catalytic performances as well as stability in the degradation of a model organic pollutant methylene blue (MB). Theoretical simulation was also carried out to illustrate the structural features of the Mn 3 O 4 /NG composite. This work presents a novel idea of designing functional materials from waste precursors.