Characterization of Ni, NiMo, NiW and NiFe electroactive coatings as electrocatalysts for hydrogen evolution in an acidic medium

The paper reports a study on the influence of alloying nickel by left-hand side transition metals (Fe, Mo, W) on the electrocatalytic activity in hydrogen evolution in an acidic environment. A number of experimental techniques were used in research (dc and ac electrochemical techniques, XRD, SEM, EDS, and ICP). The results clearly demonstrate that alloying nickel with Fe, Mo or W results in an increased electrocatalytic activity in hydrogen evolution when compared to pure nickel. Two effects were found to be responsible for the observed behavior; an increase in surface roughness and intrinsic activity of the material. Ni7.3Mo was found to yield the highest overall electrocatalytic activity among the investigated materials mainly due the highest surface roughness, while Ni3.4W was found to yield the highest intrinsic electrocatalytic activity, which is explained on the basis of the modification of electron density in d-orbitals upon alloying nickel with tungsten. It was also noticed that an increase in crystallinity can contribute to an increased electrocatalytic activity in hydrogen evolution.