Hydrogen evolution on hot and cold consolidated Ni-Mo alloys produced by mechanical alloying

Ni80Mo20 and Ni57Mo43 alloys produced by mechanical alloying (MA) were used as the electrode materials for hydrogen evolution from NaOH within a limit ed temperature range of 20-60 degreesC. To form the electrodes, the Ni-Mo a lloys were consolidated in two different ways. One was 'cold pressing', whi ch retained the original nanocrystalline structure of Ni80Mo20, and the amo rphous structure of Ni57Mo43, and another one was 'hot pressing', which pro duced multiphase systems (Ni4Mo + MoO2) and improved the mechanical propert ies of the resulting electrodes too. Appreciable cathodic current densities of similar to 100 mA cm(-2) were measured at these electrodes. The estimat ed values of the apparent activation energy for cold consolidated materials were much lower, whereas those for the exchange current were much higher t han the apparent activation energy values for a smooth, polycrystalline Ni plate. (C) 2001 Elsevier Science B.V. All rights reserved.