Abstract
Hydrogen production through water electrolysis is an eco-friendly pathway for renewable and clean energy conversion and storage, hence developing efficient, affordable, and durable electrocatalysts is essential. In this work, the catalytic activity of Nickel Cobalt Layered double hydroxide (NiCo-LDH) toward overall alkaline water splitting is investigated, and the effect of different ratios of Ni:Co in the LDH structure on the electrochemical performance is studied. NiCo-LDH is in situ prepared and grown directly on the surface of a conductive Nickel Foam (NF) electrode through a hydrothermal method with different molar ratios of both Nickel and Cobalt. The prepared NiCo-LDH/NF samples are then characterized by XRD, FTIR, SEM and XPS analyses to confirm the formation of the LDH structures. Then, the electrochemical performance was evaluated using the common electrochemical techniques of cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). Results show that 1Ni:2Co-LDH/NF is the optimum molar ratio for Hydrogen Evolution Reaction (HER), while 2Ni:1Co-LDH/NF is the optimum molar ratio for Oxygen Evolution Reaction (OER). The synthesized 1Ni:2Co-LDH/NF electrode is found to exhibit an overpotential of 253 mV at 10 mA cm-2 with Tafel slop of 65 mV/dec for HER and 2Ni:1Co-LDH/NF electrode exhibited an overpotential of 273 mV at 10 mA cm-2 with Tafel slop of 38 mV/dec for OER in 1.0 M KOH. To attain a current density of 10 mA/cm2, a low cell voltage of 1.68V is required for water splitting process with 1Ni:2Co-LDH/NF as cathode and 2Ni:1Co-LDH/NF as an anode.
Published Version
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