Alkaline Electro-Sorption of Hydrogen Onto Nanoparticles of Pt, Pd, Pt 80 Pd 20 and Cu(OH) 2 Obtained by Pulsed Laser Ablation.

Recently, hydrogen evolution reaction (HER) in alkaline media has received a renewed interest both in the fundamental research as well as in practical applications. Pulsed Laser Ablation in Liquid (PLAL) has been demonstrated as a very useful technique for the unconventional preparation of nanomaterials with amazing electro-catalyst properties toward HER, compared to those of nanomaterials prepared by conventional methods. In this paper, we compared the electro-sorption properties of hydrogen in alkaline media by Pt, Pd, Pt 80 Pd 20 , and Cu(OH) 2 nanoparticles (NPs) prepared by PLAL. The NPs were placed onto graphene paper (GP). Noble metal particles have an almost spherical shape, whereas Cu(OH) 2 presents a flower-bud-like shape, formed by very thin nanowalls. XPS analyses of Cu(OH) 2 are compatible with a high co-ordination of Cu(II) centers by OH and H 2 O. A thin layer of perfluorosulfone ionomer placed onto the surface of nanoparticles (NPs) enhances their distribution on the surface of graphene paper (GP), thereby improving their electro-catalytic properties. The proposed mechanisms for hydrogen evolution reaction (HER) on noble metals and Cu(OH) 2 are in line with the adsorption energies of H, OH, and H 2 O on the surfaces of Pt, Pd, and oxidized copper. A significant spillover mechanism was observed for the noble metals when supported by graphene paper. Cu(OH) 2 prepared by PLAL shows a competitive efficiency toward HER that is attributed to its high hydrophilicity which, in turn, is due to the high co-ordination of Cu(II) centers in very thin Cu(OH) 2 layers by OH - and H 2 O. We propose the formation of an intermediate complex with water which can reduce the barrier energy of water adsorption and dissociation.