NEW HYDROGEN CATHODES IN ACID-MEDIUM - CASE OF NICKEL ELECTRODEPOSITED WITH HETEROPOLYACIDS (HPAS)

The electrodeposition of nickel from different baths with and without heteropolyacids (HPAs) was performed. Different electrodes have been checked: electrodeposited nickel from baths without HPAs (Ni); activated Ni at the surface with HPAs (NiAHPAs) and electrodeposited nickel from baths containing HPAs (NiHPAs). The HPAs are SiW12O404- and PW12O403-. A study was carried out to investigate the influence of the HPAs on the electrocatalytic properties of the hydrogen evolution reaction (h.e.r.) on these electrodes. An important decrease of the overpotential (η) and a significant increase of the exchange current density (io) for the h.e.r. were obtained. The nickel electrode prepared with PW12O403- is more electroactive than Pt for the h.e.r. in acid medium. Further, NiHPAs is more active than NiAHPAs for the h.e.r. On the other hand, NiHPAs are less sensitive to impurity effects than Pt for the h.e.r. © 1990.