Electrostatic Self-Assembly Approach to Fabricate Architectures of Carboxyl Functionalized Gold-Aryl Nanoparticles and Graphene Oxide Platforms

Graphene oxide (GO) was decorated with gold-aryl (Au-C) nanoparticles AuNPs-COOH by sodium borohydride reduction of aryldiazonium tetrachloroaurate(III) salt at room temperature in aqueous solutions. Brunauer-Emmett-Teller measurements supported GO anchoring by AuNPs modified with COOH; surface area dropped significantly. Morphology of AuNPs-COOH/GO nanocomposite (NC) was probed using AFM and TEM, showing NC’s surface roughness and wrinkling. XPS results suggest the clear reductive reaction of tetrachloroaurate anion into metallic gold in AuNPs-COOH/GO along with detailed interpretations of functional groups’ nature. Molecular dynamics calculations endowed support of favorable wrinkling at the edges and carboxyl intercalation to GO surface of types π- π, hydrogen bonding, and hydrophobic interactions. Solvent accessible surface area calculations of GO showed a decrease in total surface area. Environmental nanoremediation of the catalytic reduction of 4-nitrophenol, a priority pollutant listed by USEPA, was investigated. The apparent rate constants Kapp of four catalytic reduction cycles of nitrophenol were measured. The highest value is 1.17 × 10-1 min-1 for the first cycle which decreased to 4.49 × 10 -2 min -1 for the fourth cycle. The variations in rate constants were measured with different conditions, including NaBH 4 concentrations, NC loadings and NC incubating time in NaBH4.