MnO₂ Nanosheets on TiO₂ Tetragonal Prism Nanoarrays as Electrode Materials for Electrochemical Energy Storage

Titanium dioxide (TiO2) tetragonal prism nanoarrays were first successfully prepared onto FTO glass using the controlled hydrothermal synthesis. Second, the manganese dioxide (MnO2) nanosheets uniformly grew onto the surface of TiO2 nanoarrays by chemical synthesis to fabricate the MnO2/TiO2 shell–core nanoarrays as supercapacitor electrode materials. The crystal structure, surface morphology, and electrochemical performance of the as-prepared electrodes were carried out by XRD, SEM, Raman analysis, XPS, and electrochemical workstation. The results indicated that the MnO2 nanosheets could uniformly distribute onto the surface of TiO2 tetragonal prism nanoarrays with thicknesses of 40–70 nm. The specific capacitance of MnO2/TiO2/FTO was 766 ± 92 F/g, which was 10 times compared with that of the TiO2/FTO at 1 A/g. The capacitance retention of the MnO2/TiO2/FTO electrode could maintain 75.0% after 5000 charge–discharge cycles. Moreover, the MnO2/TiO2/FTO electrode had an inner diffusion-controlled contribution of 58.33% at 50 mV/s, which was beneficial for electrode materials to achieve high rate performance because of the good synergistic effect between TiO2 nanoarrays and MnO2 nanosheets.