Abstract
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.
Highlights
High-performance energy storage devices are the key to the development of new energy vehicles, large-scale energy storage, and micro-/nano-devices [1, 2]
As for the temperature-dependent conductivity, two typical hopping mechanisms, called variable range hopping (VRH), which happens at low temperatures, and nearest neighbor hopping (NNH), which takes place at high temperatures, have been proposed by Mott et al for some semiconductor materials
Current-voltage curve characteristics can be explained by the ohmic mechanism of conductivity in the low electrical field (< 1024 V/cm)
Summary
High-performance energy storage devices are the key to the development of new energy vehicles, large-scale energy storage, and micro-/nano-devices [1, 2]. There are no reports concerned about the electrical transport properties of an individual NiCo2O4 nanowire. NiCo2O4 nanowires were synthesized successfully by thermal transformation from the CoNi-hydroxide precursors and the electrical transport properties and temperature-dependent conduction mechanisms of the individual NiCo2O4 nanowire device were studied systematically.
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