Abstract
The development of highly efficient, rapid, and recyclable nanocatalysts for effective elimination of toxic environmental contaminants remains a high priority in various industrial applications. Herein, we report the preparation of hybrid mesoporous gold-iron oxide nanoparticles (Au-IO NPs) via the nanocasting "inverse hard-templated replication" approach. Dispersed Au NPs were anchored on amine-functionalized iron oxide incorporated APMS (IO@APMS-amine), followed by etching of the silica template to afford hybrid mesoporous Au-IO NPs. The obtained nanoconstructs were fully characterized using electron microscopy, N-2 physisorption, and various spectroscopic techniques. Owing to their magnetic properties, high surface areas, large pore volumes, and mesoporous nature (S-BET = 124 m(2) g(-1), V-pore = 0.33 cm(3) g(-1), and d(pore) = 4.5 nm), the resulting Au-IO mesostructures were employed for catalytic reduction of nitroarenes (i.e. nitrophenol and nitroaniline), two of the most common toxic organic pollutants. It was found that these Au-IO NPs act as highly efficient nanocatalysts showing exceptional stabilities (>3 months), enhanced catalytic efficiencies in very short times (similar to 100% conversions within only 25-60 s), and excellent recyclabilities (up to 8 cycles). The kinetic pseudo-first-order apparent reaction rate constants (k(app)) were calculated to be equal to 8.8 x 10(-3) and 23.5 x 10(-3) s(-1) for 2-nitrophenol and 2-nitroaniline reduction, respectively. To our knowledge, this is considered one of the best and fastest Au-based nanocatalysts reported for the catalytic reduction of nitroarenes, promoted mainly by the synergistic cooperation of their high surface area, large pore volume, mesoporous nature, and enhanced Au-NP dispersions. The unique mesoporous hybrid Au-IO nanoconstructs synthesized here make them novel, stable, and approachable nanocatalyst platform for various catalytic industrial processes.