Nanosized rambutan-like nickel oxides as electrochemical sensor and pseudocapacitor

The development of meticulous nanoscale porous designs with advanced properties have been attracted considerable interest because of their large surface areas, dispersion of active sites at different pore length scales and shortened diffusion paths that facilitates the rapid migration of electrolyte ions. These features of porous structures have a direct link to their electrochemical performance in energy and sensing systems. In the current study we report large scale-up production, low-cost manufacturing, and high-purity product of NiO nanostructures with rambutan-like morphology (NRs) via a microwave-assisted approach. The electrochemical measurements of CV, galvanostatic charge-discharge and the impedance spectrum were used to investigate the electrochemical performance of the NiO NRs electrodes. The NiO NRs exhibit a reliable electrochemical sensor for hydroxide ion in harsh environments and high-performance recyclable pesudocapacitor. This electrochemical performance of NiO NRs is significantly related to their unique morphology, size, and pore size distribution that enhance the diffusion of the electrolyte through the 3D porous network. These key factors induced high specific capacitance and reliably detect hydroxide ions within a wide concentration range, a detection limit of 22 μM (pH 9.3), and high sensitivity of 13.9 × 10^-3 A/M. Therefore, such findings demonstrated the potential of free-standing NiO NR electrodes for developing high-performance electrochemical devices.