Interfacial synthesis of mesoporous MnO ₂/polyaniline hollow spheres and their application in electrochemical capacitors

Mesoporous MnO ₂/polyaniline composite (MP-I) has been synthesized using an interfacial synthesis technique. The results of X-ray diffraction and Fourier transform infrared spectroscopy indicate the amorphous structure of MP-I. The morphology of MP-I observed by scanning electron microscopy and transmission electron microscopy is composed of hierarchical hollow submicron spheres. The N ₂ adsorption/desorption test reveals MP-I has higher surface area (124 m ² g ^-1) and more uniform pore-size distribution than the composite (MP-C) prepared by chemical co-precipitation. The electrochemical measurements show that as electrode materials the mesoporous MP-I composite electrode yields larger specific capacitance (262 F g ^-1) with better rate capability and higher capacitance retention (93% of its initial capacitance after 800 cycles). The unique microstructure of MP-I and the coexistence of conducting polyaniline with MnO ₂ are found to be responsible for the superior electrochemical properties.