Low-temperature growth of high-quality multilayer graphene films on porous CuNi alloys for enhanced corrosion resistance.

Multilayer graphene (MLG) is an excellent protective material for engineering alloy in aqueous environments, owing to its high crystallinity and nm-scale thickness. However, achieving conformal deposition of high-quality MLG films on porous alloys without damaging their intricate microstructures remains a challenge. Herein, utilizing CuNi alloy with multiscale microstructures as surrogate models, we achieve conformal growth of high-quality, continuous, MLG films (thickness <5 nm) without damaging the porous structures at 700 °C, which is the lowest temperature reported to date for defect-free graphene growth. This breakthrough is mainly attributed to the use of methanol as the carbon source and the favorable catalytic activity of the CuNi substrates. Electrochemical tests in a corrosive solution show that the graphene-skinned porous alloy exhibits a 14-fold reduction in corrosion current density and an 8-fold increase in charge transfer resistance compared to the bare substrate. Furthermore, complete conformal coverage of MLG films is successfully validated on bulk-porous CuNi alloy, along with comparable protective efficacy. This work thus provides a universal low-temperature growth strategy for MLG on alloys with diverse structural features, enabling their stable service in aqueous environments and thus holding promise for applications in marine engineering and energy-related fields.