Synthesis of water-soluble gold-aryl nanoparticles with distinct catalytic performance in the reduction of the environmental pollutant 4-nitrophenol

• Published in: Catalysis science & technology Vol. 9; no. 21; pp. 659 - 671
• Main Authors: Ahmad, Ahmad A. L, Panicker, Seema, Chehimi, Mohamed M, Monge, Miguel, Lopez-de-Luzuriaga, Jose M, Mohamed, Ahmed A, Bruce, Alice E, Bruce, Mitchell R. M
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2019
• Subjects: Agglomeration; Agricultural wastes; Aromatic compounds; Catalysis; Catalytic activity; Crystallography; Doppler effect; Gold; Leaching; Nanoparticles; Nitrophenol; Pollutants; Red shift; Reduction; Toxicity; Viability; Water chemistry
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/c9cy01402k

Catalysis under harsh environmental conditions requires robust nanoparticles that can resist leaching of the organic shell and possess significant resistance to aggregation. Robust gold core-carbon shell gold-aryl nanoparticles (AuNPs-COOH) were fabricated by mild reduction of the water-soluble aryldiazonium salt [HOOC-4-C 6 H 4 N&z.tbd;N]AuCl 4 , and were fully characterized in solution and solid state. The nanoparticles showed high stability in the presence of 0.01-1.00 M NaCl salt, acidic and basic pH values (1-13) and moderate temperatures (20-90 °C). DFT calculations of the optimized model system Au 38 -C 6 H 4 -COOH show an Au-C (aryl) distance of 2.04 Å, which is related to a binding energy of −59.2 kcal mol −1 . The 4-nitrophenol (4-NPh) reduction model was used to study the viability of AuNPs-COOH as a catalyst. Nitrophenols are among the most common organic pollutants in industrial and agricultural wastewaters due to their toxicity, anthropogenic and inhibitory nature. The AuNPs-COOH show high catalytic activity, where the reduction of 80 μM 4-NPh was complete in less than five minutes with a high k app (2.26 × 10 −2 s −1 ) and a relatively low E a (25 kJ mol −1 ) compared to literature values. Catalytic activity decreases with subsequent cycles of the reaction, along with a decrease in intensity and red shift in the LSPR band, and an increase in aggregation of nanoparticles in the TEM following each reaction cycle. In-depth kinetic insight into the catalytic reduction of nitrophenol pollutant using gold-carbon nanoparticles is described.