Phase evolution of perovskite LaNiO3nanofibers for supercapacitor application and p-type gas sensing properties of LaOCl–NiO composite nanofibers

Abstract

This study reports the fabrication and characterization of LaOCl–NiO composite and LaNiO3 nanofiber mats and their potential applications for p-type gas sensors and electrochemical capacitors. One-dimensional LaOCl–NiO composite and LaNiO3 fibers were prepared via the electrospinning of LaNiO3 precursor/poly(vinyl acetate) composite fibers followed by subsequent thermal annealing. The size and distribution of the primary particles within the LaOCl–NiO composite and LaNiO3 fibers were largely governed by the calcination conditions (from 450 to 950 °C). The perovskite LaNiO3 phase started to form at calcination temperatures that exceeded 750 °C. Upon the formation of the perovskite LaNiO3 phase, the electrical resistivity decreased remarkably from 1.1 × 106 to 0.692 Ω cm. LaOCl–NiO composite fiber mats calcined at 550 °C and 650 °C showed p-type semiconducting gas sensing properties and exhibited significantly enhanced C2H5OH sensitivity against CO, H2, NH3 and NO2 gases. The conducting LaNiO3 fiber mats calcined at 750 °C were used as the basis of a hybrid electrochemical capacitor in which the fiber mats served as the conducting core for electrostatic spray-deposited manganese oxide overlayers. The manganese oxide/LaNiO3 stacked electrodes exhibited a high specific capacitance of ∼160 F g−1 at 10 mV s−1.