Unveiling the prospects of Y2O3-based nanocomposites: Synthesis, characterization, and electrochemical assessment for supercapacitor and biosensor applications

Abstract

Supercapacitors distinguish themselves in the realm of energy storage with their ability to discharge rapidly and their superior cycle life when compared to conventional batteries. This research is dedicated to the synthesis of graphene oxide (GO), GO-Y2O3, and GO-Y2O3 doped with Mg2+/Cr3+ through the Hummers and hydrothermal methods. The structural and electrochemical properties of the synthesized samples were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), and a CH Analyzer (Electrochemical workstation). The XRD results for both pure and doped GO-based samples indicated a cubic phase and the effective doping of Mg2+ and Cr3+ ions into the yttrium oxide matrix. Transmission electron microscopy (TEM) showed GO particle sizes of approximately 35±5 nm and the encapsulation of Y2O3:Mg2+/Cr3+ within the GO matrix GO-Y2O3:Mg2+/Cr3+ nanocomposites (NCs), with an interplanar spacing of 0.1876 nm corresponding to the (440) crystal plane. Cyclic voltammetry (CV) analysis for Y2O3 and its doped variants (Y2O3:Mg2+, Y2O3:Cr3+) showed increased current responses at various scan rates, with distinct peaks and a current peak ratio of less than 1, indicative of a quasi-reversible system. The electrodes based on Y2O3 and (Y2O3:Mg2+, Y2O3:Cr3+) NCs achieved maximum specific capacitance values of 172.54 Fg⁻¹, 279.98 Fg⁻¹, and 791.59 Fg⁻¹, respectively, at a scan rate of 2 mV/s. Galvanostatic charge-discharge (GCD) profiles for these yttrium-based samples yielded capacitance values of 71.66 Fg⁻¹, 112.77 Fg⁻¹, and 370 Fg⁻¹, respectively, with the highest value observed for Mg2+ doped samples. Additionally, the Y2O3:Mg2+ samples showcased superior charge transport within the electrode material, leading to a higher energy density of 18.5 Wh/kg compared to the Y2O3:Cr3+ and pure Y2O3 samples. Electrochemical impedance spectroscopy (EIS) of the Mg2+ and Cr3+ doped yttrium samples showed a linear response in both the low and high-frequency regions, demonstrating their enhanced charge storage capability. Notably, the Y2O3:Mg2+ sample achieved the highest capacity retention of 94.25%. The combination of Y2O3 and Mg2+ led to improved capacitance retention and efficient charge storage, with a Coulombic efficiency of 91.9%, compared to the pure sample. Additionally, the sensitivity and selectivity studies of Mg2+ and Cr3+ doped Y2O3 samples suggested that these developed nanocomposite materials hold potential for biosensor applications.