Graphene encapsulation protocol for hydrogen charging of atom probe tomography specimens and analysis of hydrogen penetration

Hydrogen penetration into and distribution within metallic materials are critical factors in hydrogen embrittlement. This study investigated the penetration of hydrogen/deuterium (H/D) at the near-atomic scale in graphene-coated pipeline steel specimens using atom probe tomography (APT). The specimens were prepared by a novel graphene encapsulation protocol, either before or during H/D charging, and the effect of H/D penetration was quantitatively assessed by APT measurements of H/D concentration and distribution. The results demonstrate that graphene encapsulation during H/D-charging of APT specimens enables a robust room-temperature workflow for near-atomic-scale characterisation of H/D in steels by APT. The results also provide direct evidence that graphene film acts as a diffusion barrier for H/D and has the potential to protect materials against H ingress. • Novel protocol for graphene encapsulation during electrochemical H/D charging of atom probe tomography (APT) specimens. • Protocol offers a practical room-temperature workflow for preserving trapped H/D in APT specimens. • APT provides direct evidence that graphene is a diffusion barrier for H/D with potential to protect against H ingress.