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

Titanium dioxide (TiO 2 ) tetragonal prism nanoarrays were first successfully prepared onto FTO glass using the controlled hydrothermal synthesis. Second, the manganese dioxide (MnO 2 ) nanosheets uniformly grew onto the surface of TiO 2 nanoarrays by chemical synthesis to fabricate the MnO 2 /TiO 2 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 MnO 2 nanosheets could uniformly distribute onto the surface of TiO 2 tetragonal prism nanoarrays with thicknesses of 40–70 nm. The specific capacitance of MnO 2 /TiO 2 /FTO was 766 ± 92 F/g, which was 10 times compared with that of the TiO 2 /FTO at 1 A/g. The capacitance retention of the MnO 2 /TiO 2 /FTO electrode could maintain 75.0% after 5000 charge–discharge cycles. Moreover, the MnO 2 /TiO 2 /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 TiO 2 nanoarrays and MnO 2 nanosheets.