Hydrogen evolution reaction on smooth Ni (1-x) + Mo (x) alloys (0 < x < 0.25)

M.R. GENNERO DE CHIALVO; A.C. CHIALVO

JOURNAL OF ELECTROANALYTICAL CHEMISTRY - (Print)

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 1998 vol. 448 p. 87 - 93

1572-6657

The hydrogen evolution reaction was studied on smooth electrodes of nickel + molybdenum alloys with atomic compositions equal to 0, 1, 3, 5, 10, 20 and 25% Mo in 2 M NaOH at 30°C. The alloys were prepared by melting in an induction furnace and arranged as rotating disc electrodes. X-ray diffraction patterns indicate that these alloys are solid solutions with a f.c.c. nickel-rich structure corresponding to the α phase. It has been determined that at low overpotentials (η < 0.2 V) the electrocatalytic activity follows the order 25% Mo ≅ 3% Mo > 20% Mo ≅ 10% Mo > 0% Mo ≅ 1% Mo ≅ 5% Mo. In the high overpotentials region, the differences in the electrocatalytic behaviour are less significant, that of 25% Mo being the less active due to its high Tafel slope. The kinetic parameters of the elementary steps (θe, α, jov, mH, mT) corresponding to the Volmer-Heyrovsky-Tafel mechanism were evaluated starting from the dependences log j vs. η. From these values, the kinetic parameters of the net reaction were calculated and the results obtained were analysed and discussed.