Tuning the hydrogen evolution reaction at the Pt(111) surface with 2D material and non-precious metal

The hydrogen evolution reaction (HER) is the process where protons from the electrolyte combine with the electrons from the metal electrode catalyst to produce atomic hydrogen adsorbed on the metal surface. The reaction ends when these hydrogen atoms then form molecular hydrogen and thereby desorbs from the surface of the catalyst. The bonding between the catalyst and the proton should be optimal such as to favour the formation of adsorbed H atom and at the same time not so strong as to hinder the H2 molecular desorption to occur. The main applications of HER are in the cathodic half cells of water splitting and fuel cells. The efficiency of such a cathodic material depends on how strongly or weakly the H atoms are adsorbed on the metal catalyst. We present an experimental and theoretical study of the state of the art HER metallic electrocatalyst platinum (Pt) by tuning its reactivity with graphene (Gr) and iron (Fe). Using density functional theory (DFT) the reactivity of hydrogen (H) in the two systems namely Gr/Pt(111) and Gr/Fe/Pt(111) is investigated. The presence of Gr is observed to increase the selectivity/permeability to protons [1] and at the same time weaken the H adsorption compared to bare Pt [2]. This should favour H diffusion at the interface and hence H2 molecular desorption. The H adsorption weakens further in the presence of Fe and even more with Gr and Fe. In addition to platinum the performance of gold (Au) in the presence of Fe and Gr has also been studied and compared in this work.