Microwave-Reduced Uncapped Metal Nanoparticles on Graphene: Tuning Catalytic

ABSTRACT This 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 area covalently implant, stabilize, and support bare-surfaced gold nanoparticles (BSGNs) produced in situ by a unique microwave reduction process. Comparing the efficiency of catalytic reductionofp-nitroaniline ( p-NA)byBSGNsand similar sized surfactant-cappedgold 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 bare GO by∼3 fold, and (b) increases the conductivity of native p-type GOby>10 fold via injection of 1.328 1012 electrons/cm2, consequently transforming it into an n-type semi-conductor. SECTION Nanoparticles and Nanostructure