Effect of chromium (Cr)-doping on electrochemical performance of microwave synthesized hematite (α-CrxFe2−xO3) nanosheets for supercapacitor application

Metal ion-doped transition metal oxides have been proposed as new electrode materials for developing high-performance energy storage devices. For supercapacitor applications, novel Chromium-doped iron oxide (Cr-doped α-Fe2O3) with sheet like morphology were fabricated by utilizing the Microwave route. The Cr-doped α-Fe2O3 nanosheets provided a large reaction area and fast electron transport which are desired for improving the electrochemical properties. The electrochemical properties of α-CrxFe2−xO3 (x = 0, 0.03, 0.06) electrodes were comprehensively studied using Cyclic voltammetry (CV), Galvanostatic Charging and discharging profiles and electrochemical impedance Spectroscopy in 3 M KOH electrolyte solution within a potential window of − 0.2 to 0.55 V. The 6% Cr-doped Hematite exhibited maximum redox activity because of its larger surface area and offered a specific capacitance of 1243 Fg−1 at a scan rate of 5 mVs−1 greater than pure α-Fe2O3 nanostructures. In addition, the 6% Cr doped sample showed less cyclic fatigue with 95.8% capacitance retention after 5000 CV cycles and a better conductivity with a resistance of only 2.57 Ω. Finally, an asymmetric Supercapacitor was designed, which showed a high energy density of 28.803 Wh Kg− 1 at a power density of 586.68 WKg−1 and a good cyclic stability. The findings demonstrate that Cr-doped Hematite as electrode materials have potential application for high performance supercapacitors and may provide real solutions to the energy crisis.