Microwave-Reduced Uncapped Metal Nanoparticles on Graphene: Tuning Catalytic, Electrical, and Raman Properties

The work addresses a major challenge in liquid phase catalysis by enabling the synthesis of solvent dispersible uncapped metal nanoparticles (NPs) with enhanced density of accessible catalytic sites. We demonstrate that graphene oxide's (GO's) high density of accessible and bondable oxy-functional groups and the high steric hindrance from its micrometer-scale are convalently implant, stabilize, and support bare-surfaced gold nanoparticles (BSGNs); produced in situ by a unique microwave reduction process. Comparing the efficiency of catalytic reduction of p-nitroaniline (p-NA) by BSGNs and similar, sized surfacant-capped gold NPs showed that the uncapped surface on GO supported NPs (a) opens up 258% more active sites and (b) enhances the catalytic reduction of p-NA by 10-100 fold Further, BSGN implantation on GO, (a) amplifies the Raman signal of bar GO by similar to 3 fold and (b) increase the conductively of native p-type GO by > 10 fold via injection of -1.328 x 10(12) electrons/cm(2) consequently transforming it into an n-type semi-conductor.