Fabrication of amine functionalized graphene oxide – AgNPs nanocomposite with improved dispersibility for reduction of 4-nitrophenol

In the present work, graphene oxide (GO) was synthesized through modified Hummer's method and the covalent functionalization of GO was achieved via amino moiety using N,N′-dicyclohexylcarbodiimide (DCC) as coupling agent and ethylenediamine (EDA) & 1,3-diaminopropane (DAP) as amino precursors. The amino functionalized GO served as nucleation and growth sites for silver nanoparticles. These two amino functionalized graphene oxide-AgNPs were compared based on the chain length of the alkyl-diamine and metal loading capacity. Further, these two nanocomposites were characterized using FTIR, UV, Raman, XPS and TEM analyses. We reported that these alkyl-diamine-functionalized graphene oxides had superior dispersibility in different polar solvents with reduced agglomeration of Ag nanoparticles and had control over the size of Ag nanoparticles in the range of 5–10 nm. The catalytic efficiency of these two types of amine functionalized GO-AgNPs nanocomposite were assessed based on the reduction of 4-nitrophenol. The reduction outcomes revealed that the kobs value for DAP functionalized AgNPs (7.548 × 10−4 s−1) was comparatively superior than GO-EDA-AgNPs (3.345 × 10−4 s−1) due to the variation in chain length. Optimization of parameters like [substrate], [NaBH4] and catalyst load was also investigated and found to possess influence on kobs values.