RESUMO
We herein report a novel, energy-saving and environmentally benign photodeposition approach to fabricate a manganese oxide film on hydrogenated TiO2 (H-TiO2) nanotube arrays using a Mn(2+)-containing solution as a precursor. Mn(2+) ions are oxidized to Mn3O4 by the photogenerated holes during the photodeposition. The preferential growth of Mn3O4 on the nucleation sites leads to the formation of Mn3O4 nanorods on each H-TiO2 nanotube, forming a 3D hierarchical Mn3O4/H-TiO2 composite film. The as-fabricated 3D hierarchical Mn3O4/H-TiO2 composite film electrode delivers a high specific capacitance of 508 F g(-1) at a current of 0.7 A g(-1). The composite film electrode still shows a specific capacitance of 228 F g(-1) even at a high rate of 35.7 A g(-1), demonstrating its prominent rate capability. Remarkably, the composite film electrode shows no obvious capacitance decay after 10,000 charge/discharge cycles at a current density of 3.6 A g(-1), revealing its superior electrochemical cycling stability. The prominent pseudocapacitive performance of the composite film electrode can be attributed to its unique structure characteristics. The as-constructed energy-saving and environmentally benign photodeposition method can be used as a general and efficient route to prepare other composite materials with controlled morphologies and dimensions.
RESUMO
We have observed similar surface color changes of glassy carbon (GC) after anodic "electrodeposition" with the same electrolytes in the presence or the absence of silanes, indicating that sample color changes can arise from more than one thing and thus should not be used as the sole indicator of silica film formation. Nevertheless, the formation of silicate films during anodic electrodeposition is verified by X-ray photoelectron spectroscopy (XPS) measurements.
