Study of the catalytic activity of 3D macroporous Ni and NiMo cathodes for hydrogen production by alkaline water electrolysis

Platinum is the electrode material with the highest catalytic activity for the hydrogen evolution reaction (HER). However, its high cost and scarcity are the two major barriers for its usage in the industrial alkaline water electrolysis, which requires searching for other cheaper and more available materials with good catalytic activity. Ni-based materials have attracted more and more attention due to their good activity for the HER and sufficient corrosion resistance in alkaline solutions at considerable low cost. According to the Brewer intermetallic bonding theory, molybdenum alloyed with nickel (hypo–hyper-d-electronic transition metal) could improve the intrinsic catalytic activity for the HER. In this work, Ni and NiMo metallic coatings were galvanostatically electrodeposited on a stainless steel AISI 304 substrate by means of the double-template electrochemical process. The evaluation of these electrodes as H2-evolving cathodes was done in 30 % wt. KOH by pseudo-steady-state polarization curves and electrochemical impedance spectroscopy (EIS) at different temperatures. From Tafel curves results, it is shown that the NiMo electrodes have higher catalytic activity than Ni. On the other hand, from EIS results, it is possible to conclude that the NiMo electrodes showed higher intrinsic catalytic activity for HER than the pure Ni electrode as a consequence of alloying hypo–hyper-d-electronic transition metals.