Synthesis and characterization of Au-modified macroporous Ni electrocatalysts for alkaline water electrolysis

Au nanoparticles (Au-NPs) were successfully synthesized and incorporated into the surface of a macroporous Ni electrode fabricated via galvanostatic electrodeposition at high current densities in order to produce hydrogen by means of alkaline water electrolysis. The developed electrodes were morphologically characterized by means of confocal laser scanning and field emission scanning electron microscopes. The electrocatalytic behaviour towards the hydrogen evolution reaction was studied by Tafel polarization curves and electrochemical impedance spectroscopy. It was clear that enlarging the real surface area of an electrode its catalytic activity was greatly enhanced. This improvement was further increased when Au-NPs were added to the macroporous Ni surface. In this case, the improvement was not only caused by enlarging the surface area but also by an improvement in the intrinsic catalytic activity of the alloy, as it was shown by the exchange current densities values, calculated from the real surface area.