Exploiting the photocatalytic activity of gold nanoparticle-functionalized niobium oxide perovskites in nitroarene reductions

Abstract

Novel gold nanoparticle-doped niobium perovskites are synthesized using a chemical reduction technique, affording supported nanoparticles on the order of 8–10 nm. The UVA-initiated photocatalytic activity of the nanocomposites was studied using nitroarene reduction as a probe reaction which yielded the corresponding aminoarenes in as little as 3 hours with yields up to 92%. Analyses of kinetic data, using Hammett parameters and computational methods, show that electron-withdrawing groups accelerate the photocatalytic process and suggest that electron transfer from the gold nanoparticle surface to the nitro group is an integral part of the rate-limiting step of this reaction. The linearity of the Hammett plot shows that no change in the photocatalytic mechanism can be expected upon variation of the para-aryl substitution. Investigation of the reaction mechanism using CH₃OH-d₄ illustrates that CH₃OH is the most likely source of protons, as both electrons and protons are required for successful photoreduction. Moderate recyclability of the heterogeneous nanomaterial over three catalytic cycles is observed.