Carboxymethylcellulose-based magnetic Au or Ag nanosystems: Eminent candidates in catalysis, sensing applications based on SERS, and electrochemistry

Abstract An increasing demand for metal gold- and/or silver-based nanomaterials in optics, catalysis, and electrochemical sensing research calls for the development of a new, clean, and environmentally friendly methodology for the production of metal-containing composites. Herein, we report a novel method for fabrication of dispersed carboxymethylcellulose stabilized iron oxide nanoparticles capable to adsorb silver and gold ions onto the surface. Simultaneously, Ag or Au ions are trapped on the magnetic carrier surface and reduced into metal nanoparticles without the action of another reducing agent. The magnetic silver nanocomposite with dumbbell-like structures and magnetic gold nanocomposite with strawberry-like structures, both of different composition (5, 10, and 20 wt.% metal contents), were prepared and characterized by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, and atomic absorption spectroscopy. Subsequently, the prepared magnetic silver and gold nanocomposites (cMNPs-Ag and cMNPs-Au, respectively) were studied as sufficient candidates in catalysis, sensing applications based on SERS, and electrochemistry. The catalytic properties were demonstrated with the reduction of 4-nitrophenol to 4-aminophenol as a model reaction, where very high rate constants of nanocomposites ranging between 0.25 and 4.12 min −1 were determined. The TOF values were calculated to be from 20.87 to 95.34 min −1 . Glassy carbon electrodes modified with cMNPs-Au or cMNPs-Ag nanocomposites were used for successful determination of H 2 O 2 by means of cyclic voltammetry. Obtained results revealed the well-defined reduction peak around −0.45 V indicating small overpotential necessary for H 2 O 2 detection and detection limits were found to be 2.82 × 10 −7  mol L −1 (cMNPs-Au) and 3.04 × 10 −7  mol L −1 (cMNPs-Ag). Utilization of nanocomposites as active SERS substrates was demonstrated on the analysis of Rhodamine 6G. The determined enhancement factors were 2  ×  10 7 (cMNPs-Au, 20 wt.% Au content) and 3.2 × 10 7 (cMNP-Ag, 20 wt.% Ag content).