Electroless Deposition of Silver on Multiwalled Carbon Nanotubes Using Iodide Bath

Abstract

Electroless deposition of silver on multiwalled carbon nanotubes (MWCNTs) was investigated using an iodide bath. Prior to electroless deposition of silver, the MWCNTs were chemically oxidized and then pre-treated using a typical two-step method (sensitization and activation) to form catalytic palladium nuclei on the MWCNTs. Dimethylaminoborane (DMAB) was used to reduce silver ions. Electroless deposition of silver was carried out at 25 C with variation of the pH. The microstructure of the deposits was evaluated using field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The silver iodide complex ion species present was determined to be AgI 4 3À from equilibrium potential measurements. Silver was selectively deposited on palladium nuclei on the surface of the MWCNTs and continuous diffusion of deposited silver and palladium nuclei resulted in a solid solution of Ag-Pd alloy particles on the MWCNTs at pH ¼ 7.5. Carbon nanotubes (CNTs) (Refs. 1, 2) exhibit excellent mechanical characteristics, including high tensile strength and high elastic modulus, and have high thermal conductivity. CNTs are also expected to be applied as a superior support for catalytic nanoparticles due to their chemical and physical stability and large specific surface areas.Silver nanoparticles have unique optical 3-8 and antibacterial properties, 9-12 and catalytic properties for glucose oxidation. 13-15Among the fabrication methods employed to form silver nanoparticles on supports such as CNTs, electroless or chemical deposition methods are considered to be the most effective with respect to uniform distribution and minimized cost. The formation of silver nanoparticles on CNTs by electroless deposition has been reported, 16,17 in which ammonium baths that contain ammonia as the silver ion complexing agent are widely used. [17][18][19][20] However, fulminating silver compounds such as silver nitride (AgN 3 ) and silver amide (AgNH 2 ) may form in the ammonium baths. Iodides such as potassium iodide are known as a complexing agent for silver ions, and therefore silver electrodeposition baths using iodide have been investigated as noncyanide baths. [21][22][23][24] However, electroless deposition of silver from an iodide bath has not been reported. The fabrication of silver nanoparticles on CNTs without the use of toxic or fulminating baths would be valuable not only for practical applications, but also from an academic perspective. Therefore, the electroless deposition of silver on CNTs was investigated using an iodide bath. ExperimentalEstimation of silver iodide complex ion species.-Silver iodide complex ion species were estimated using equilibrium potential measurements. Equilibrium potentials were measured using an electrochemical measurement system (Hokuto Denko HZ-3000) at 25 C without agitation. AgI was dissolved in 1.5 M KI solution at various concentrations. Pure silver and platinum plates, and a saturated calomel electrode (SCE) were used as working, counter, and ...

Compositional effect on the fabrication of AgxPd1−x alloy nanoparticles on c-plane sapphire at distinctive stages of the solid-state-dewetting of bimetallic thin films

“…32,33 In the isolated Ag-Pd NPs, the Ag and Pd are completely miscible at any proportion due to the same crystallographic structure with the similar lattice parameters and no miscibility gap at any composition based on the Ag-Pd alloy phase diagram. 34 In contrast to the monometallic dewetting, the bilayer dewetting can be slightly different and indeed somewhat more complex due to the various factors such as different diffusivity, surface energies, surface segregation, alloying, lattice mismatch and stress generation-relaxation between constituent materials, etc. Therefore, the dewetting extent can be signicantly varied even at identical growth conditions such as annealing temperature, thickness and duration by the alteration of composition or sequence of individual atomic species.…”

Dispersion of multiwalled carbon nanotubes into a diglyme solution, electrodeposition of aluminum-based composite, and improvement of hardness

“…By referring some reports, 14,20,22 the multi-walled carbon nanotubes (MWCNTs) were acid treated with ultrasonication in 3:1 (volume ratio) H2SO4 aq (98wt%)/HNO3 aq (68wt%) for 6 h. The sample was filtered and washed with deionized water until the pH of the filtrate water became neutral. The filtered MWCNTs were dried for 12 h under vacuum at 120°C.…”

“…They have been used to produce metal-MWCNTs composites such as Ni, Ag and Cu, which were electroplated from MWCNTs-dispersed aqueous baths. 20,21,22 Since Al cannot be electrodeposited from aqueous baths, non-aqueous baths such as organic and ionic liquid baths have been investigated. [23][24][25] However, there has been only one report about electrodeposition of Al-MWCNTs, where an ionic liquid bath was used.…”

Electrodeposition of Ni-W/CNT Composite Plating and Its Potential as Coating for PEMFC Bipolar Plate

“…The effects of the hydrothermal treatment of CNT in mixed acid solution was investigated. Acid treatment of CNT is a widely-used method to impart hydrophilicity to CNT [29] but it has been reported that an additional dispersant should be added because it is difficult to obtain sufficient dispersibility by acid treatment alone [30]. Therefore, in this study, hydrothermal treatment of CNT was applied in a mixed acid solution, which may not require additional dispersants which may deteriorate the electrical conductivity.…”