Modulation of n-type and p-type characteristics in hydrogenated graphene at room temperature: protocol and mechanism

Abstract

Hydrogenation has emerged as a promising approach to induce semiconducting properties in graphene. However, control over its doping type and level without sacrificing structural integrity has been a challenge. Furthermore, the semiconducting behavior of hydrogenated graphene—specifically whether it exhibits n-type or p-type characteristics—remains unclear, and the doping mechanisms influenced by various environmental conditions have not been fully elucidated. In this study, we introduce a new, non-destructive protocol for doping type and level control of graphene through repeated cycles of hydrogenation and air exposure. We demonstrate clearly that pristine metallic graphene converts into an n-type semiconductor upon hydrogenation in vacuum and subsequently to p-type semiconductor behavior when exposed to ambient air. We identify that oxygen adsorption is the primary source responsible for this transition. Our study provides not only a protocol to control doping but also fundamental insights into the doping mechanism of hydrogenated graphene depending on the surrounding environment, which present a versatile approach for tuning the overall electronic properties of graphene via surface modification.