Characteristics of a sintered porous Ni-Cu alloy cathode for hydrogen production in a potassium hydroxide solution

A porous Ni-Cu alloy with a most probable pore size of 2.4 μm and an open porosity over 31.5% was synthesized by step sintering pressed compacts consisted of mixed Ni and Cu powders in a vacuum furnace. The electrocatalytic activity and stability of the fabricated porous Ni-Cu alloy as cathode for the HER (hydrogen evolution reaction) in 6.0 mol/L potassium hydroxide solution were investigated by cathodic current-potential curves, CV (cyclic voltammetry) and EIS (electrochemical impedance spectroscopy) techniques. Results show that the onset potential of the porous Ni-Cu for HER greatly shifts to the positive direction compared with the dense Ni and dense Ni-Cu alloy. The electrochemical activation energy is determined to be 26.7 kJ mol^-1 for the porous Ni-Cu alloy, against 44.1 kJ mol^-1 and 32.6 kJ mol^-1 for the dense Ni and dense Ni-Cu alloy, respectively. The increased activity of the porous Ni-Cu alloy for HER is related to the micro-porous structure as well as synergistic interaction of Ni and Cu. Besides, the fabricated porous Ni-Cu alloy displays good corrosion resistance in potassium hydroxide solution during the immersion test, which makes it possible for long-time running as cathode in the process of hydrogen evolution reaction.