Graphene on Nanoscale-Thick Au Films: Implications for Anticorrosion in Smart Wearable Electronics

Abstract

Gold is normally considered inert to chemical reaction. Nevertheless, as a common electrode material, it would suffer from corrosion when exposed to certain solutions such as sweat and body fluids. Here, we report low-temperature plasma-enhanced chemical vapor deposition (PECVD) of graphene on gold and demonstrate its feasibility for anticorrosion application. The effects of hydrogen-to-methane ratio and the underlying gold substrate on the graphene growth are investigated, and the growth mechanism of PECVD graphene on gold is proposed. When immersed in an oxygenated saline solution, the PECVD-grown graphene-covered gold surface is found to remain intact after an acceleration soaking test at 90 °C for 24 h, which is in contrast to the degradation of bare gold surface subject to the same test. Our findings suggest that consumer/medical wearables and implantable devices with exposed gold can benefit from the protection of a direct, low-temperature PECVD-grown graphene layer for anticorrosion, thereby prolonging the efficacy and reliability of gold electrode-based biosensors.

Low-Temperature Direct Growth of Nanocrystalline Multilayer Graphene on Silver with Long-Term Surface Passivation

“…Given the fact that Ag and Au have the same carbon solubility and therefore the same catalytic activity, the growth mechanism of graphene on silver is expected to be similar to the surface adsorption mechanism on Au. In this context and noting a previous work by Lu et al on PECVD graphene growth on Au that demonstrated bilayer graphene growth for H 2 /CH 4 ≥ 1 after 5 min, our finding of bilayer graphene growth on silver for the same growth time (5 min) with H 2 /CH 4 = 4 appeared to be consistent with the previous report.…”

“…These findings clearly demonstrate that the silver surface was well protected by the multilayer graphene despite of its nanocrystalline size. The excellent passivation may be attributed to the fact that multiple graphene layers with turbostratic stacking could significantly hinder the diffusion pathways of moisture or oxygen molecules from reaching the silver surface. , …”

“…Recently, Kim et al have further lowered the required temperatures for PECVD growth of graphene by forced convection to increase the reaction probability of excited species or radicals on the substrate surface before their recombination. To date, the reported growth temperatures for various PECVD graphene synthesis methods are found to range from 160 to 700 °C on various substrates. ,− …”