Insights into the inherent properties of vertical graphene flakes towards hydrogen evolution reaction

Abstract

Nowadays, major research efforts are being carried out, in order to fulfil the demand for sustainable hydrogen production. To accelerate this process, it is important to develop efficient and inexpensive materials, going beyond precious metals and, if possible, using metal-free electrocatalysts. Carbon compounds could be an ideal candidate material, thanks to their abundancy in nature and the possibility to be organised in nanostructures with beneficial morphologies. Here, we report the deposition of vertical graphene flakes, otherwise known as graphene nanowalls (GNWs), in various metallic and non-metallic substrates and we present results on the inherent electrocatalytic activity towards hydrogen evolution reaction (HER) in acidic electrolyte. Analysis shows that when GNWs are deposited on top of an electrode with a higher inherent activity, overall activity is limited as GNWs block ion diffusion. When GNWs are deposited on electrodes with poorer activity, the inherent activity of GNWs is predominant. In addition, GNWs are successfully deposited on flexible electrodes and are applied to durability tests, including operation after manual bending, showing very good stability. Above all, the present study reports for first time the inherent electrocatalytic activity of GNWs towards HER. The results suggests that this carbon materials can be used in the development of novel catalysts.