Composition-Dependent Pseudocapacitive Properties of Self-Supported Nickel-Based Nanobelts

In this work, we have developed a system to prepare self-supported nickel-based nanobelts of similar morphology but varying chemical compositions. After a simple hydrothermal treatment, phase-pure self-supported nickel sulfate hydroxide (Ni(SO4)(0.3)(OH)(1.4)) nanobelts can be directly prepared on a nickel foam substrate, which can be converted into NiO nanobelts by calcination without any change in the morphology. Alternatively, the pristine Ni(SO4)(0.3)(OH)(1.4) nanobelts can be transformed into Ni3S2 nanobelts via a facile hydrothermal sulfidization. When these nanobelts were applied in supercapacitors they demonstrated contrasting performances, with the Ni3S2 nanobelts showing a high reversible capacitance of about 3.5 F cm(-2) at 10 mA cm(-2) over 1000 cycles, while the Ni(SO4)(0.3)(OH)(1.4) sample delivered insignificant capacitance. This huge difference in electrochemical activity relates to dramatically different amounts of charge being stored within their bulks, with charge and discharge rates limited by the bulk ionic resistance rather than interfacial charge transfer resistance. Overall it is concluded that chemical composition has a more dominant role than morphology in determining the physicochemical properties of these materials.