Synthesis by Spray Pyrolysis of Gold Nano Species Confined in Iron Oxide Nanospheres Effective in the Reduction of 4-Nitrophenol to 4-Aminophenol

The highly effective Au/Fe2O3-@Au/Fe2O3nanoreactors for the 4-nitrophenol (4-NP) reduction are successfully obtained by one-pot synthesis using the spray pyrolysis (SP) technique. The Au/Fe2O3-@Au/Fe2O3nanoreactors manifest superior catalytic activity in the reduction of 4-NP in the presence of sodium borohydride (NaBH4) compared to gold-iron oxide nanoreactors prepared via a colloidal approach. The negative effect of the reaction product accumulation, the 4-aminophenol (4-AP), on the catalytic reduction of 4-NP over Au/Fe2O3-@Au/Fe2O3is examined by a direct pre-injection of 4-AP to the reaction media. To the best of our knowledge, it is the first experimental evidence of gold active sites blocking by 4-AP. All obtained samples are characterized by the yolk-shell spherical hollow structure mainly consisted of two embedded hollow nanospheres. The reduction of iron oxide precursor concentration diminishes the diameter of final iron oxide nanospheres. According to STEM-EDS analysis and STEM, Au nano species are uniformly dispersed on both iron oxide nanospheres. The SP technique presently used to synthesize Au/Fe2O3-@Au/Fe2O3nanoreactors manifests high potential for the one-pot fabrication of a large variety of nanoreactors with various active materials applied as heterogeneous catalysts in numerous catalytic processes.