Controlling the adsorption behavior of hydrogen at the interface of polycrystalline CVD graphene

Abstract

Polycrystalline graphene films were synthesized from renewable biomaterials in ambient air using a facile and rapid thermal chemical vapour deposition technique. Characterization of the graphene reveals a large surface area, the presence of nanoscale domains and open edges, atomic-level stacking, and high electrical conductivity, which are favorable features for electrochemical hydrogen evolution reactions (HERs). The numerous boundaries and open edges accelerate the gas diffusion process and enlarge the effective reactive surface area for gas evolution, which is responsible for a significant improvement of HER performance and stability compared to a commercial graphene film. The hydrogen adhesion behavior in investigated for both bare Ni foil/foam and graphene grown on Ni foil/foam samples. The hydrogen gas bubbles adhere to the polycrystalline graphene for a long period of time before detaching, in contrast to their behavior on the pristine Ni foil surface. Post treatment of the graphene film using plasma treatment increases the desorption rate of hydrogen bubbles from the surface. The results indicate a wide range of possibilities for use of graphene-based catalysts in electrocatalytic gas evolution reactions.