▎ 摘　　要

Highlighting the roles of H-2 on the carbon dissolution and diffusion-out unit steps in the metal substrate is highly imperative to constitute a whole puzzle elucidating how the H-2 affects the graphene chemical vapor deposition (CVD) growth, taking into account that the effects of H-2, on the surface process have been intensively emphasized. In this article, we designed a series of graphene growth experiments by introducing the H-2 in the individual unit step on the Cu and Co films as a comparison due to their distinctively intrinsic carbon solubility. We investigated the effects of H-2 on the crystallographic structure, surface morphology, and chemical environment of metal substrates, and the thickness and quality of as-grown graphene films. We also established the theoretical models to monitor the interaction between carbon and metal atoms with and without H-2. Our results demonstrate that the H-2 predissolution could suppress the carbon dissolution in the Cu film and enhance the diffusion-out of dissolved carbon atoms, whereas in the Co film the converse would occur.