Influence of co-catalyst amount/size for selective hydrogenation of 1,3-dinitrobenzene over Au-mTiO2 nanocomposites under visible light

Abstract

This study demonstrates the co-catalytic effect for selective hydrogenation of a particular group in a multifunctional organic compound. Transmission electron microscopy (TEM) studies revealed that Au loaded nanoparticles were found to be of ∼3.89 nm and ∼8.86 nm with 1 wt% and 3 wt% metal loading respectively by homogeneous deposition precipitation (HDP) method over synthesized mesoporous titanium dioxide (m-TiO2) nanoparticles. The Au particles were deposited in the metallic state which was confirmed from X-ray photoelectron spectroscopy (XPS) with a binding energy of 84.0 eV and 87.7 eV credited to 4f5/2 and 4f7/2 spin states respectively. In this Au-mTiO2 heterojunction, metal particles found to be decisive for 100% selective hydrogenation of 1,3-dinitrobenzene under visible light. Predominantly, m-nitroaniline formed when 1,3-dinitrobenzene was treated with 1 wt% Au-mTiO2 whereas 100% photoreduction of both nitro groups occurred with 3 wt% Au-mTiO2. Hence, 1,3-dinitrobenzene exhibited particle size sensitive photocatalytic hydrogenation under mild conditions without using any reducing agent.