Growth of MnO2 nanoflakes on TiO2 nanorods for pseudocapacitor

Abstract

In this work, we report the synthesis of TiO2 (core)/MnO2(shell) nanorods by a redox reaction and TiO2 nanorods generated in-site from H-titanate nanorods during hydrothermal process. The MnO2 nanoflakes were grown densely on TiO2 nanorods to form core-shell nanorods. Owing to the strong TiO2-MnO2 interfacial interaction and enriched oxygen vacancies, TiO2/MnO2 nanorods are highly active and stable as capacitive electrodes. The quantitative analysis of XPS shows more oxygen vacancies were generated in the TiO2/MnO2 materials. The specific capacitance of TiO2/MnO2 is 368.9 F/g, more than double of 140.8 F/g on the MnO2 materials. At 1.5 A/g, 92% of the initial capacitance of the TiO2/MnO2 was still retained after 3000 charge-discharge cycles. However, the specific capacitance on the pure MnO2 materials lost 39% after 3000 cycles. Our results suggest that the improved capacitive properties of TiO2/MnO2 are closely related to enriched oxygen vacancies, unique structure, higher surface area, as well as interfacial interaction between TiO2 and MnO2.