Palladium nanoparticle deposition via precipitation: a new method to functionalize macroporous silicon

Abstract

We present an original two-step method for the deposition via precipitation of Pd nanoparticles into macroporous silicon. The method consists in immersing a macroporous silicon sample in a PdCl2/DMSO solution and then in annealing the sample at a high temperature. The impact of composition and concentration of the solution and annealing time on the nanoparticle characteristics is investigated. This method is compared to electroless plating, which is a standard method for the deposition of Pd nanoparticles. Scanning electron microscopy and computerized image processing are used to evaluate size, shape, surface density and deposition homogeneity of the Pd nanoparticles on the pore walls. Energy-dispersive x-ray spectroscopy (EDX) and x-ray photoelectron spectroscopy (XPS) analyses are used to evaluate the composition of the deposited nanoparticles. In contrast to electroless plating, the proposed method leads to homogeneously distributed Pd nanoparticles along the macropores depth with a surface density that increases proportionally with the PdCl2 concentration. Moreover EDX and XPS analysis showed that the nanoparticles are composed of Pd in its metallic state, while nanoparticles deposited by electroless plating are composed of both metallic Pd and PdOx.

Palladium Nanoparticles Grown by Using Successive Ionic Layer Adsorption and Reaction Method: Ethanol Electrooxidation and Electrochemical Quartz Crystal Microbalance Studies

“…immersing the activated seed layer coated substrate in a plating solution containing PdCl 2 and a reducing agent for formation of Pd nanoparticles. 28,29 Scheen et al deposited palladium nanoparticles by precipitation method to overcome the drawbacks of electroless plating such as multistep reaction, inhomogeneity, cluster formation and oxide formation of Pd. In precipitation method the substrate (macroporous silicon wafer) was immersed in a solution of PdCl 2 and dimethyl sulfoxide kept at 60 °C for 1 h and then immediately annealed in an inert environment at 450 °C.…”

“…The precipitation method was compared with electroless plating method where precipitation method showed uniformly distributed metallic Pd nanoparticles. 29 Highly dispersed Pd nanoparticles having uniform size distribution were deposited by Safavi et al using phosphorylated ionic liquid as a reducing and complexing agent. The process involved deposition of a xerogel (formed by mixing tetraethoxysilane, hydrochloric acid and ionic liquid powder and allowing to gelate) over a glass slide by immersing it for 15 s and drying naturally for several days and the immersion of this xerogel coated glass slide in palladium acetate solution for 1 h. 30 2+ ionic solution in alumina membrane.…”