The interaction of oxygen with Ni(100) and the reduction of the surface oxide by hydrogen

The interaction of oxygen with Ni(100) has been studied with ellipsometry, Auger electron spectroscopy and low energy electron diffraction. The observations of other workers are completely confirmed. The same techniques and procedures have been used to study the reduction of the surface oxide with hydrogen. It is found that the reduction reaction requires hydrogen atoms, adsorbed on exposed nickel atoms. At temperatures between 150 and 250°C and hydrogen pressures up to 10-5 Torr, the reduction proceeds via a nucleation and growth type mechanism, with an activation energy of 23 kcal/mol