Substrate mediated properties of gold monolayers on SiC

In light of their unique physicochemical properties two-dimensional metals are of interest in the development of next-generation sustainable sensing and catalytic applications. Here we showcase results of the investigation of the substrate effect on the formation and the catalytic activity of representative 2D gold layers supported by non-graphenized and graphenized SiC substrates. By performing comprehensive density functional theory (DFT) calculations, we revealed the epitaxial alignment of gold monolayer with the underlying SiC substrate, regardless of the presence of zero-layer graphene or epitaxial graphene. This is explained by a strong binding energy (similar to 4.7 eV) of 2D Au/SiC and a pronounced charge transfer at the interface, which create preconditions for the penetration of the related electric attraction through graphene layers. We then link the changes in catalytic activity of substrate-supported 2D Au layer in hydrogen evolution reaction to the formation of a charge accumulation region above graphenized layers. Gold intercalation beneath zero-layer graphene followed by its transformation to quasi-free-standing epitaxial graphene is found to be an effective approach to tune the interfacial charge transfer and catalytic activity of 2D Au. The sensing potential of substrate-supported 2D Au was also tested through exploring the adsorption behaviour of NH3, NO2 and NO gas molecules. The present results can be helpful for the experimental design of substrate-supported 2D Au layers with targeted catalytic activity and sensing performance.

Automated summary

In this study, the formation and catalytic activity of 2D gold layers supported by non-graphenized and graphenized SiC substrates under substrate effect were investigated. Through DFT calculations, we found that the gold monolayer exhibited epitaxial alignment with the underlying SiC substrate regardless of the presence of zero-layer or epitaxial graphene. This was attributed to the strong binding energy (about 4.7 eV) of 2D Au/SiC and the significant charge transfer at the interface, enabling the penetration of electric attraction through graphene layers. Intercalation of gold beneath zero-layer graphene followed by transformation to quasi-free-standing epitaxial graphene was found to effectively tune the interfacial charge transfer and catalytic activity of 2D Au. The sensing potential of substrate-supported 2D Au was also demonstrated through the adsorption behavior of NH3, NO2, and NO gas molecules. These findings can aid in the experimental design of substrate-supported 2D Au layers with targeted catalytic activity and sensing performance.