Catalytic Nanoreactors of Au@Fe₃O₄ Yolk–Shell Nanostructures with Various Au Sizes for Efficient Nitroarene Reduction

Abstract

Au@Fe3O4 yolk–shell nanocatalysts based on the thermal decomposition of iron pentacarbonyl in the presence of 2.5–10-nm Au core nanoparticles were successfully fabricated for the catalytic reduction of nitroarenes. The particle sizes of the Au@Fe3O4 nanostructures were in the range 8–15 nm, with Fe3O4 shell layer thicknesses of 2.0–2.4 nm. The Fe3O4 layer not only can form a magnetic shell for recovery but also enables the protection of the catalytic activity of the Au core nanoparticles toward the reduction of nitrobenzene derivatives including 2-nitrophenol, 4-nitrophenol, 4-nitrotoluene, and 1-chloro-4-nitrobenzene in the presence of NaBH4. The catalytic performance of Au@Fe3O4 is highly dependent on the particle size of the Au core materials and the substituent groups of the nitroarenes. The reduction rates of nitroarenes with electron-withdrawing groups were found to be 2.3–2.6 times higher than those of nitroarenes with electron-donating groups. In addition, the reduction of nitroarenes by the Au@Fe3O4 yolk–shell nanocatalysts was found to be a surface-mediated reaction, and the relationship between the reduction rate and the initial NaBH4 concentration was found to follow Langmuir–Hinshelwood kinetics. Moreover, the yolk–shell nanoparticles showed good separation ability and reusability, as they could be repeatedly applied for the nearly complete reductions of 4-nitrophenol and 1-chloro-4-nitrobenzene for at least five successive cycles. These unique properties make Au@Fe3O4 nanocatalysts an ideal platform for tailoring yolk–shell nanoreactors with various active materials and also for studying various heterogeneous catalytic processes.

Persea americanaseed extract mediated gold nanoparticles for mercury(ii)/iron(iii) sensing, 4-nitrophenol reduction, and organic dye degradation

“…Moreover, Av-AuNPs acted as a redox catalyst in the degradation/reduction of organic pollutants and dyes by electron relay effect between donor and acceptor molecules. Various reports 23,39,[41][42][43][44][45][46][47][48] are available on catalytic activity of gold nanoparticles for the reduction of major organic pollutant 4-NP and degradation of organic dyes MB, MO and DB24. From the reports (Table 2), it is clear that as the size of the gold nanoparticle decreases the required time span for the reduction or degradation of organic pollutant or dyes also decreases with increasing catalytic efficiency.…”

Impact of nanoparticles on neuron biology: current research trends

“…94 In another report, AgNPs induced inflammatory response in neuronal cells. 9 It was reported that AgNPs entered the nuclei of mouse neuronal cells and induced progression of neurodegenerative disorder. 9 It was reported that silver nitrate treatment increased cellular superoxide dismutase activity and decreased mitochondrial membrane potential, leading to neuronal death.…”

“…[1][2][3] Nanoparticles can be synthesized in different sizes (1.0-500 nM) and shapes (cones, cubes, rods, tubes, and shells). [4][5][6] There are various applications of nanoparticles in biotechnology, biosensing, catalysis, magnetic fluids, separation techniques, energy storage, and environmental modification [7][8][9][10][11][12] and also in biomedical field, especially in diagnostics, and drug or gene delivery. [13][14][15][16][17][18][19] Interestingly, nanoparticles have been extensively used as drug carrier systems for therapeutic molecules with the primary aim to improve the therapeutic effect and decrease their side effects and drug/gene delivery.…”

Citrate Stabilized Au‐FexOy Nanocomposites for Variable Exchange Bias, Catalytic Properties and Reversible Interaction with Doxorubicin

“…The conversion of 4‐NP (4‐nitrophenol, substrate A) through absorption spectroscopy for different nanocomposites has been reported as model catalytic reaction as the absorbance change of this reagent is simplistic to monitor . Similar to these studies, repetitive reduction cycles of 4‐NP and more than 90% conversation for each reaction cycle up to 8 cycles (Figure S15) in presence of catalyst 5Fe suggest the stability and reusability of 5Fe in the reaction condition.…”