Molybdenum trioxide for supercapacitor application: defining the role of temperature and electrolyte

The need to optimize basic synthesis parameters to get energy storage electrode with controlled structure and morphology cannot be overemphasized in getting improved specific capacitance among other supercapacitor properties. Here in, α-MoO₃ electrodes were synthesized at low spray temperature of 200 ℃ and below as compared to high spray temperature in the literature. The prepared films were tested using XRD, SEM, EDS, UV–Vis, and electrochemically in three electrodes configurations in 1.0 M of KOH (unblended electrolyte) and 0.5 M LiOH/0.5 M KOH (blended electrolyte) electrolytes using galvanostatic charge/discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results showed α-MoO₃ structure of the films with increase in the crystallite size (29.1–31.5 nm), nanosheet to pebble-like morphologies, and decrease in the bandgap (3.1–2.78 eV) from spray temperature of 150 ℃, to 200 ℃. The greatest specific capacitance displayed by the electrode was 1070 and 865 F/g in LiOH/KOH and KOH, respectively, with about 89.5% capacitive retention in LiOH/KOH. The results gotten show that the as-prepared α-MoO₃ is a promising material for supercapacitor electrode.