Hierarchical porous MnO2/CeO2 with high performance for supercapacitor electrodes

Hierarchical porous manganese dioxide/cerium dioxide (MnO2/CeO2) nanocomposite material as supercapacitor electrode was synthesized by hydrothermal method. Through synergistic effects from good reversible redox reaction characteristics of CeO2 and well cycling performance of MnO2, we obtained binary composite metal oxide with preferable capacitance, rate capability and cycling stability. XANES, FT-TR and XRD results indicate that MnO2/CeO2 composite (α-MnO2 and fluorite CeO2 respectively) has been prepared successfully with good crystallinity. SEM, TEM, HRTEM and Mapping reveal that CeO2 particles with loose distribution uniformly grow along MnO2 nanorods surface. The particle size largely reduces, and the agglomeration relieves evidently with loose structure and even arrangement. N2 adsorption tests show that BET specific surface areas (SBET) of MnO2/CeO2 are larger than that of original single component. MnO2/CeO2 is typical hierarchical mesoporous material with more widespread pore structure and distribution, much different from MnO2 and CeO2 being rich microporous materials. SBET and specific capacitance (Csp) of the optimal composite in this work (MnO2/CeO2-1) are up to 73.4 m2 g−1 and 274.3 F g−1 respectively, much higher than that of pure MnO2 (20.6 m2 g−1 and 190.2 F g−1) and CeO2 (63.6 m2 g−1 and 66.2 F g−1). After 1000 charge-discharge cycles, the Csp no longer decreases and remains 93.9%. In addition, MnO2/CeO2-1 obtains a low Rs, Rct and Zw. It is a good supercapacitor electrode material generally.