Assessing pseudocapacitive and OER-HER electrocatalytic potential of bimetallic Copper-Nickel/Graphene oxide nanocomposite

• Spinel Cu-Ni oxide/GO nanocomposite in electrochemical charge storage & catalysis. • Pseudocapacitive charge storage with a power density of ∼267 W/kg @ 1 A/g. • 8000 cyclic runs under 3 & 2-electrodes mode result capacity retention of ∼85 %. • OER η = 340 mV is superior to other reported graphene-metal oxide composites. • Low HER η = 359 mV also establishes its dual-mode electrocatalysis aspect. Copper-nickel oxide/GO (CNO/GO) nanocomposite was synthesized via a low-temperature thermal reduction technique with crystallographic phase matching with an off-stoichiometric type Cu 0.05 Ni 0.95 O/GO structure. Three-electrode-based electrochemical experiments suggest that the prepared CNO/GO nanocomposite can store energy via the pseudocapacitive mechanism. The charge storage efficacy is also reflected in the high-power density value (∼267 W/kg) achieved at a current density of 1 A/g compared to earlier reported nickel oxide-based composites. The practical performance of the CNO/GO nanocomposite can be corroborated by the fact that in a symmetric coin cell device, it results in a specific capacity of ∼37F/g @ 1A/g and retains its ∼84 % specific capacity after 8000 cycles. The flexibility of using CNO/GO nanocomposite as an exceptional electrocatalytic material can be recognized from the smaller overpotential (η) values, e.g., 340 mV and 359 mV for OER and HER , respectively, in conjunction with chronoamperometric stability retained over 24 h. All these multiple electrochemical attributes establish the potential of using CNO/GO nanocomposite in energy storage and conversion.