Surface modification of Ni foam by the dendrite Ni-Cu electrode for hydrogen evolution reaction in an alkaline solution

Hydrogen is a renewable energy source that is considered among the candidate alternatives to fossil fuels. In this research, dendrite Ni-Cu coating is the electrodeposited and catalytic performance of this electrode is investigated toward hydrogen evolution reaction (HER) in 1.0 M KOH. The response surface methodology (RSM) as the design of experimental (DOE) method is used for optimizing the intrinsic electrocatalytic HER activity (Ni-Cu A) and active surface area (Ni-Cu B) of the dendrite Ni-Cu coating. The DOE results showed that the active surface area had a stronger effect on the electrocatalyst HER activity than the intrinsic parameter. The eta(10) (overpotential at 10 mA cm(-2)) and Tafel slope of the Ni-Cu B electrode were 202 mV vs. RHE and 82 mV dec(-1), respectively. According to the Tafel slope of the optimized Ni-Cu B electrode, the Volmer-Heyrovsky mechanism predominated the HER mechanism. The Ni-Cu B electrode showed high electrocatalytic activity and electrochemical stability compared to recently proposed catalysts. The electrocatalyst stability of the Ni-Cu B electrode led to the small size of the H-2 bubble on the surface of the electrode. The low size and rapid detachment of the H-2 gas bubbles resulted in the dendrite Ni-Cu B structure. (C) 2019 Elsevier B.V. All rights reserved.