Enhanced pseudocapacitive performance of transition metal doped MoO3 nanorods

Abstract

Rising energy demands from rapid technological advancements drive the development of high-performance devices, with supercapacitors playing a key role due to their fast charge-discharge capabilities. Research on metal-doped transition metal oxides seeks to enhance energy storage efficiency, charge-discharge rates, and long-term stability, improving electrochemical performance and scalability. The present work explored the impact of metal doping on the electrochemical performance of molybdate nanoparticles, aiming to enhance specific capacitance and rate capabilities. We synthesized pure MoO₃ and Fe-, Co-, and Ni-doped MoO₃ nanorods using a hydrothermal method, varying doping concentrations (α = 2 %, 4 %, 6 %, 8 %). Extensive characterization was conducted, including X-ray diffraction (XRD), electron microscopy (SEM, TEM), cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS), highlighting the effects of dopants and their concentrations. XRD confirmed the formation of pure MoO₃, Fe-, Co-, and Ni-doped MoO₃ with monoclinic phases and crystallite sizes of 48.9 nm, 40.6 nm, 39.7 nm, and 25.6 nm, respectively. Nickel-doped MoO₃ (NMO) exhibited nanorod morphology, increasing active sites and surface area for high-rate electrochemical reactions. NMO demonstrated outstanding electrochemical performance, achieving 167.95 F/g at 0.5 A/g and 99.79 % retention over 15,000 cycles at 12 A/g. A 6 % doping concentration significantly enhanced electrochemical properties, particularly with nickel, making NMO for supercapacitors, meeting the rising demands in energy storage solutions.