Pt alloys with transition metals for hydrogen evolution

Abstract

Nowadays, the use of fossil fuels is exaggerated and the development and optimization of technologies capable of fulfilling human society’s energetic needs is utterly important. Not only fossil fuels are a non-renewable source of energy, but they are also harmful for the environment and the population. A possible alternative for replacing fossil fuels and internal combustion energies for automotive applications are low-temperature fuel cells. The fuel used in those cells is H2 and the electrochemical process only produces water as by-product. Sustainable supply of H2 must be guaranteed if those technologies are to be globally adopted. However, currently more than 90 % of the H2 produced comes from steam reforming of natural gas and other light fossil fuels. Alternatively, hydrogen can be produced electrochemically by means of the hydrogen evolution reaction (HER) in water electrolyzers. The best catalyst for that purpose is platinum, an expensive and scarce metal. Therefore, alloying is an appealing option to reduce the loading of Pt during hydrogen evolution. Furthermore, positioning a subsurface layer of transition metals increases the activity of the electrolyzer. In this research work, using density functional theory calculations, the computational hydrogen electrode and a simple descriptor-based analysis, we determined the best near-surface alloys (NSAs) of Pt and transitions metals for the HER. We determined that for (111) facets of Pt NSAs the best alloying candidates are Fe, Co and Re. Instead, for (100) facets of Pt NSAs the best alloying candidates are Y and Mo