Synthesis of PVP stabilized Cu/Pd nanoparticles with citrate complexing agent and its application as an activator for electroless copper deposition.

A simple method has been developed to synthesize Cu/Pd nanoparticles in aqueous solution in ambient condition with the addition of complexing agent, trisodium citrate. UV-vis spectra confirmed the complexing behavior of trisodium citrate and metal ions. The particles synthesized with trisodium citrate were well dispersed with particle size ranging between 3-4 nm while the particles without trisodium citrate were larger and aggregated, as demonstrated by transmission electron microscopy (TEM). X-ray diffraction patterns (XRD) indicated the formation of bimetallic nanoparticles without impurities in the complexing agent-supplemented system. In contrast, large amounts of PdO and Cu(OH)(2) were precipitated along with the formation of particles in the complexing agent-free system. X-ray photoelectron spectroscopy (XPS) revealed small amounts of oxidized Pd on the surface of particles and the existence of zerovalent Cu and oxidized Cu in particles with trisodium citrate. With a simpler process for electroless copper deposition, the Cu/Pd nanoparticle activator with less Pd metal used exhibited comparable catalytic activity to conventional Pd/Sn colloidal activator. In summary, application of Cu/Pd nanoparticles synthesized with the complexing agent as an activator suggested a novel, simpler and inexpensive process in PCB industry.

Novel method for the synthesis of hydrophobic Pt-Ru nanoparticles and its application to preparing a Nafion-free anode for the direct methanol fuel cell.

Pt-Ru alloy is a bimetallic catalyst most commonly used in the direct methanol fuel cell (DMFC). In this paper, a new process to synthesize an unsupported Pt-Ru colloid has been introduced. The characteristics of synthesized nanoparticles were identified by XRD, TEM/EDX, and SEM, and it shows that Ru atoms are incorporated into the Pt fcc structure and the well-dispersed particles (diameter approximately 4 nm) possess a Pt-rich feature. This catalyst shows a hydrophobic characteristic which can adsorb very well on the hydrophobic-treated carbon paper or carbon cloth without the need of Nafion. Accordingly, this method can avoid particle agglomeration, and the synthesized catalyst demonstrates strong adsorption with carbon paper. In addition, this colloid-type Nafion-free catalyst was measured via linear sweep voltammetry (LSV) and exhibited electrochemical activity for methanol oxidation comparable to the commercial one with Nafion binding.

Investigation of electrodeposition of Bi2Te3 nanowires into nanoporous alumina templates with a rotating electrode.

A rotating electrode was employed to investigate the electrodeposition of Bi2Te3 nanowires. We found that mass transport of electrolytes into alumina templates of high aspect ratio plays a significant role in determining the properties of the obtained wires since diffusion is the rate-determining mechanism of mass transport within these nanochannels. In addition to slow growing rate, the effect of mass transport causes a slight composition variation from the bottom to the top of the wires. With a rotating electrode, the composition variation along the wires can be reduced by shortening the concentration depleted zone from the bulk electrolyte to the opening of pores. The wire growing rate can consequently be increased. Moreover, the wire compositions were confirmed to be adjustable by varying the rotation speed under the limitation of using a thin template.

Chemical preparation of Pd nanoparticles in room temperature ethylene glycol system and its application to electroless copper deposition.

Room-temperature synthesis of Pd nanoparticles protected by polyvinylpyrrolidone (PVP) has been successfully achieved by merely adding sodium hydroxide (NaOH) acting as accelerator for the reduction of Pd(II) in ethylene glycol (EG) without any externally added reducing agent. The Pd particle sizes were controlled in the range from 8.6 to 2.4 nm by changing the concentration of NaOH from 0 to 3.2x10(-1) M. The particle formation was monitored by UV-vis spectroscopy and the microstructure of Pd nanoparticles was analyzed by TEM and XRD. The product of adding NaOH in EG was characterized by FTIR and a -CHO group which possesses reductive ability was identified. In addition, the prepared Pd nanoparticle could serve as an effective activator for electroless copper deposition (ECD) on epoxy substrate, which is an essential process in the printed circuit board (PCB) industry. In contrast to existing commercial activators, the new activator shows superior stability and excellent performance for ECD.

Synthesis of Ag/Pd nanoparticles via reactive micelles as templates and its application to electroless copper deposition.

Ag/Pd nanoparticles have been synthesized with a reactive alcohol-type surfactant, sodium dodecyl sulfate (SDS), without the presence of an external reducing agent. Both UV-vis absorption spectra and X-ray diffraction patterns for the bimetallic and physical mixtures of individual nanoparticles revealed the formation of a bimetallic structure. Based on this method, an ordered 3D grapelike nanostructure was formed, possibly due to transformation of the liquid crystal phase of the micelles. Data from the energy-dispersive X-ray analysis show that the composition of bimetallic nanoparticle is approximately equal to the feeing solution. Furthermore, the Ag/Pd nanoparticles exhibit distinct catalyst for electroless copper deposition and may be a substitute for the conventional palladium system, which is expensive and unstable in operation.