Phase evolution of perovskite LaMO3 nanofibers for supercapacitor application and p-type gas sensing properties of LaOCl-NiO composite nanofibers

摘要

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 x 10~6 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 °G 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).