Enrichment efficiency of noble alloying elements on magnesium and effect on hydrogen evolution.

Highlights • Noble element enrichment on Mg quantified by Particle-induced X-ray Emission. • Enrichment efficiency of Au (≈10%) was higher than In (≈4%) for their binary Mg alloys. • Cathodic activation efficiency was greater for Mg alloyed with In than with Au. • Noble element enrichment on Mg has a minor effect on overall H 2 evolution rates. Abstract The role of noble element enrichment as cathodic sites for hydrogen evolution during the anodic polarisation of magnesium was evaluated by direct quantification of indium and gold enrichment using Particle-Induced X-ray Emission (PIXE). Magnesium alloyed with gold was shown to have a higher enrichment efficiency than magnesium alloyed with indium. However, the anodically induced 'cathodic activation' efficiency of magnesium alloyed with indium was higher. The estimated hydrogen evolution occurring at sites of enriched indium or gold was seen to be very small compared to the measured overall increased hydrogen evolution upon the respective alloys during anodic polarisation. [ABSTRACT FROM AUTHOR]