Hybrid nanostructured bismuth-cobalt oxides/hydroxides binder-free electrodes fabricated by two-step electrodeposition for high-performance supercapacitors

Herein, a two-step electrodeposition technique is adopted for the binder-free fabrication of nanostructured bilayered active material electrodes to achieve a high-performance supercapacitor with reducing charge-transfer resistance. Hybrid nanostructured bismuth-cobalt oxides/hydroxides electrode (Bi₂O₃@Co(OH)₂) active materials are successfully grown on a 3D nickel foam substrate via versatile electrodeposition. Nanostructured Co(OH)₂ is deposited on Bi₂O₃ coated nickel foams using different electrolytic concentrations (the comparable concentration ratios of Bi:Co = 1:0.5; 1:1; 1:1.5; 1:2). The prepared Bi₂O₃@Co(OH)₂ electrode materials are characterized for structural, morphological, elemental composition, element distribution, and chemical states of atoms properties using standard, sophisticated tools. Cyclic voltammetry is recorded at increasing scan rates, whereas galvanostatic charge-discharge data are measured at different current densities. The optimized electrode with the mole ratio of Bi:Co = 1:1 (denoted as BC-II) revealed a higher areal capacitance than Bi₂O₃ and Co(OH)₂ electrodes. The optimal BC-II electrode exhibited the highest 947.1 mFcm⁻² areal capacitance for current density 2 mA cm⁻² in 1.0 M KOH solution using the discharging time. The capacitance stability after 1000 GCD cycles at 10 mA cm⁻² is maintained at 99.8% of its original value. The present study demonstrates a simple method for preparing active nanostructured oxide/hydroxide hybrid materials for improved supercapacitors.