Using Metal Substrate to Enhance the Reactivity of Graphene towards Diels-Alder Reactions

The Diels-Alder (DA) reaction, a classic cycloaddition reaction involving a diene and a dienophile to form a cyclohexene, is among the most versatile organic reactions. Theories have predicted thermodynamically unfavorable DA reactions on pristine graphene owing to its low chemical reactivity. We hypothesized that metals like Ni could enhance the reactivity of graphene towards the DA reactions through charge transfer. Results indeed showed that metal substrates enhanced the reactivity of graphene in the DA reactions with a diene, 2,3-dimethoxy butadiene (DMBD), and a dienophile, maleic anhydride (MAH), with the activity enhancement in the order of Ni>Cu, and both are more reactive than graphene supported on silicon wafer. The rate constants were estimated to be twice higher for graphene supported on Ni than on silicon wafer. The computation results support the experimentally obtained rate trend of Ni>Cu>SiO2. This study opens up a new avenue for enhancing the chemical reactivity of pristine graphene through substrate selection.