Copper molybdenum sulfide nanoparticles embedded on graphene sheets as advanced electrodes for wide temperature-tolerant supercapacitors

Abstract

A novel hybrid of Cu₂MoS₄ nanoparticles embedded on reduced graphene oxide (rGO) sheets was prepared via a one-pot hydrothermal method without any surfactants or templates. The electrochemical properties of the as-prepared Cu₂MoS₄–rGO electrode were investigated as an advanced electrode for supercapacitor applications, and it exhibited higher specific capacitance (231.51 F g⁻¹ at 5 mV s⁻¹) compared to the pristine Cu₂MoS₄ electrode (135.78 F g⁻¹ at 5 mV s⁻¹). The Cu₂MoS₄–rGO electrode showed energy density of 31.92 Wh kg⁻¹ at a constant current of 1.5 mA, which was higher than that of the pristine Cu₂MoS₄ electrode (17.91 Wh kg⁻¹ at a constant current of 1.5 mA). The satisfactory enhancement in the electrochemical performance of Cu₂MoS₄–rGO electrodes could be attributed to the chemical interaction between rGO sheets and Cu₂MoS₄ nanoparticles, which produced more active sites for the charging/discharging process and enabled fast electron transport through the graphene layers. Furthermore, this work presented an extensive study about the effect of temperature (from 25 °C to 80 °C) on the Cu₂MoS₄–rGO electrode in an aqueous Na₂SO₄ electrolyte. The effect of temperature on the electrochemical properties of the Cu₂MoS₄–rGO electrode was investigated using cyclic voltammetry (CV), charge–discharge (CD) tests and electrochemical impedance spectroscopy (EIS). The electrochemical performance of the Cu₂MoS₄–rGO electrode exhibited ∼128% improvement at 80 °C compared to that at 25 °C in CD profiles. These experimental results indicate a fundamental comprehension of the temperature-dependent supercapacitor electrodes for industrial, military and space applications.