Combustion synthesis of spinel structured NiCo2O4 nanostructures: An efficient material for gas sensing and supercapacitor electrode applications

Abstract

Nanostructured spinel NiCo2O4 powder has been effectively synthesized using the solution combustion technique. The synthesized material was annealed at 500 °C and further utilised for gas sensing and energy storage applications. The thermal, structural, optical, electrical, magnetic and morphological properties of synthesized material were investigated in detail. The annealed synthesized NiCo2O4 powder was tested for the electrochemical studies with galvanostatic charge-discharge (GCD), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and cyclic stabilitytests for the supercapacitor electrode applications. The specific capacitance (CS), energy density (E) and power density (P) of the synthesized materials were estimated from the GCD plot and it was 730 F/g, 16.22 WhKg−1 and 398.71 Wkg-1 respectively at the current densities 2 A/g. The fabricated electrode from NiCo2O4 powder had an initial retention of capacitance value is 92.23 % after 5000 cycles. The synthesized material was further tested with different gases detection at various temperatures. The fabricated NiCo2O4 sensor was used for the estimation of gas sensing properties of acetone, carbon dioxide, ammonia and ethanol gases at various working temperatures. The gas-detection measurements illustrate that the NiCo2O4 material reacts differently to various gases at different temperatures and observes maximum sensitivity, superior selectivity, quick response and recovery ability for the ammonia gas as compared with other test gases. The feasible NH3 gas detection mechanism is pictorially presented in this manuscript. The present works conclude that nanostructured spinel NiCo2O4 is the promising material in the high performance electrode material for supercapacitor applications and ammonia gas sensing application.