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 limited temperature range of 20–60°C. To form the electrodes, the Ni–Mo alloys were consolidated in two different ways. One was ‘cold pressing’, which retained the original nanocrystalline structure of Ni80Mo20, and the amorphous structure of Ni57Mo43 and another one was ‘hot pressing’, which produced multiphase systems (Ni4Mo+MoO2) and improved the mechanical properties of the resulting electrodes too. Appreciable cathodic current densities of ∼100 mA cm−2 were measured at these electrodes. The estimated values of the apparent activation energy for cold consolidated materials were much lower, whereas those for the exchange current were much higher than the apparent activation energy values for a smooth, polycrystalline Ni plate.