Temperature-Dependent Electrical Transport Properties of Individual NiCo₂O₄ Nanowire

Understanding the electrical transport properties of individual nanostructures is of great importance to the construction of high-performance nanodevices. NiCo₂O₄ nanowires have been investigated widely as the electrodes in electrocatalysis, supercapacitors, and lithium batteries. However, the exact electrical transport mechanism of an individual NiCo₂O₄ nanowire is still ambiguous, which is an obstacle for improving the performance improvement of energy storage devices. In this work, NiCo₂O₄ nanowires were prepared successfully by thermal transformation from the CoNi-hydroxide precursors. The electrical transport properties of an individual NiCo₂O₄ nanowire and its temperature-dependent conduction mechanisms were studied in detail. The current-voltage characteristics showed that an ohmic conduction in a low electrical field (< 1024 V/cm), Schottky emission in a middle electric field (1024 V/cm < E < 3025 V/cm), and Poole-Frenkel conduction at a high electric field (> 3025 V/cm). A semiconductive characteristic is found in the temperature-dependent conductivity in the NiCo₂O₄ nanowire; the electrical conduction mechanism at low temperature (T < 100 K) can be explained by Mott's variable range hopping (VRH) model. When the temperature is greater than 100 K, electrical transport properties were determined by the VRH and nearest neighbor hopping (NNH) Model. These understandings will be helpful to the design and performance improvement of energy-storage devices based on the NiCo₂O₄ nanowires.