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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. Hybridnanostructured bismuth-cobalt oxides/hydroxides electrode (Bi 2 O 3 @Co(OH) 2 ) active materials are successfully grown on a 3D nickel foam substrate via versatile electrodeposition. Nanostructured Co(OH) 2 is deposited on Bi 2 O 3 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 Bi 2 O 3 @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 Bi 2 O 3 and Co(OH) 2 electrodes. The optimal BC-II electrode exhibited the highest 947.1 mFcm À2 areal capacitance for current density 2 mA cm À2 in 1.0 M KOH solution using the discharging time. The capacitance stability after 1000 GCD cycles at 10 mA cm À2 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. K E Y W O R D Sbinder-free electrodes, bismuth-cobalt oxides/hydroxides (Bi 2 O 3 @Co(OH) 2 ), electrodeposition, hybrid nanostructures, supercapacitors | INTRODUCTIONRecently, industrial growth has significantly increased energy consumption. 1 Although fossil fuels are the primary source of energy in industrial sectors, they are nonrenewable and release greenhouse gases, such as CO, CO 2 , SO x , and NO x , which significantly contribute to global temperature increase and pollution. 2 Renewable energy generation and storage devices are being developed to meet the ever-increasing energy demand. Among