Chemical reactivity imprint lithography on graphene: Controlling the substrate influence on electron transfer reactions

TL;DR

This study reveals how substrate choice influences electron transfer reactions on graphene, demonstrating that substrate-induced electronic effects can be spatially patterned to control chemical functionalization and protein attachment.

Contribution

It introduces reactivity imprint lithography (RIL) as a novel method to control and pattern chemical reactivity on graphene via substrate engineering.

Findings

Reactivity varies significantly with substrate type.

Raman spectroscopy characterizes substrate effects on graphene.

RIL enables spatial patterning of chemical groups and proteins.

Abstract

The chemical functionalization of graphene enables control over electronic properties and sensor recognition sites. However, its study is confounded by an unusually strong influence of the underlying substrate. In this paper, we show a stark difference in the rate of electron transfer chemistry with aryl diazonium salts on monolayer graphene supported on a broad range of substrates. Reactions proceed rapidly when graphene is on SiO_2 and Al_2O_3 (sapphire), but negligibly on alkyl-terminated and hexagonal boron nitride (hBN) surfaces. The effect is contrary to expectations based on doping levels and can instead be described using a reactivity model accounting for substrate-induced electron-hole puddles in graphene. Raman spectroscopic mapping is used to characterize the effect of the substrates on graphene. Reactivity imprint lithography (RIL) is demonstrated as a technique for spatially patterning chemical groups on graphene by patterning the underlying substrate, and is applied to the covalent tethering of proteins on graphene.