A structure of MnO2 embedded in CMK-3 framework developed by a redox method

A new in situ reduction method has been developed to synthesize a novel structured MnO2/mesoporous carbon composites with MnO2 nanoparticles embedded in the wall of ordered mesoporous carbon CMK-3 materials. KMnO4 was easy to be reduced into MnO2 in a short time in the presence of carbon, meanwhile the carbon atoms on the surface were oxidized into C–OH, CO and COOH species, making the surface more hydrophilic, and permanganate ions more readily to access, which leads to the embedded structure. The MnO2/CMK-3 composite materials were characterized using thermogravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), nitrogen sorption, transmission electron microscopy (TEM), and energy-dispersive X-ray (EDX) spectroscopy. The results show that different MnO2 contents could be introduced into the pores of CMK-3 treated with an aqueous solution of potassium permanganate, while retaining the ordered mesostructure and larger surface area. Increasing the MnO2 content did not result in a decrease in pore size from the data of nitrogen sorption isotherms, indicating that MnO2 nanoparticles are embedded in the pore wall, as evidenced by TEM observation.