Efficient Reusable Gold-Mesoporous Silica Nanocatalysts for Aromatic Nitro Reduction: Role of Phenolic Chelating Ligands on Immobilizing Gold Nanoparticles and Catalytic Activity

Abstract

Developing heterogeneous metal nanocatalysts is highly desirable since the catalyst can be easily separated and reused for several times. In this manuscript, we have immobilized gold nanoparticles (AuNPs) on the surface of mesoporous silica (SiO[Formula: see text] using simple amino acid-based phenolic chelating molecules and utilized as highly reusable catalyst for nitroarene reduction. The synthesized nanocomposites (Au@SiO2-1 and Au@SiO2-2) have been unambiguously confirmed using powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), high resolution-transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Interestingly, Au@SiO2-1 exhibited highly enhanced 4-nitrophenol reduction that was studied using absorption spectroscopy. Further catalytic activity of Au@SiO2-1 was also explored for 2-nitroaninline and 4-nitroaniline. The reusable studies demonstrated that the catalyst did not show significant change in the activity up to ten cycles. After catalytic reactions studies confirmed the strong attachment of AuNPs on the SiO2 matrix.