Reduction of Supported Noble-Metal Ions Using Glow Discharge Plasma

Abstract

A novel plasma reduction method has been developed to reduce supported noble-metal ions without the use of any reducing chemicals. H2PtCl6, PdCl2, AgNO3, and HAuCl4 supported on nonporous TiO2 and porous gamma-Al2O3 and HZSM-5 were reduced using an Ar glow discharge plasma. Optical absorption spectra and X-ray photoelectron spectroscopy show that the supported metal ions are completely reduced to metallic species. Transmission electron microscopy shows that the prepared metals are amorphous clusters and homogeneously distributed with nanoscale sizes. X-ray diffraction also confirms that the plasma-reduced metals exist as small crystallites or amorphous clusters. Thermal annealing of plasma-reduced samples at elevated temperature transforms the clusters into crystals with a slight increase in particle sizes, but the sizes are still smaller than those of H2-reduced metals. O2 glow discharge plasma can also reduce noble-metal ions, accompanied by production of a small amount of oxides. Plasma reduction is very promising for the preparation of metal nanoparticles and supported metal catalysts.

Reduction of Pd/HZSM-5 Using Oxygen Glow Discharge Plasma for a Highly Durable Catalyst Preparation

“…The procedure is the same as the method reported previously [7,10,11]. The HZSM-5 powder (SiO 2 /Al 2 O 3 = 50, purchased from the Catalyst Plant of Nankai University, Tianjin, China) is first impregnated with an aqueous solution of PdCl 2 and hydrochloric acid over night, and then dried at 50°C for 4 h. The amount of Pd-loading was 0.5, 1 and 2 wt.%.…”

“…Argon was previously used as the plasma forming gas. During the plasma catalyst treatment, Pd species was first reduced into metallic Pd species by argon plasmas [7,10,11]. A highly dispersed Pd catalyst was then obtained after further calcination thermally [7].…”

Concepts for the Stabilization of Metal Nanoparticles in Ionic Liquids

“…[172][173][174] Ag, [175] Cu [176,177] and Al [177] nanoparticles, e.g., can be prepared by treating a solution of the corresponding salt in an ionic liquid with a low temperature ionized Ar plasma, which results in electron transfer into the liquid phase (close to the interface) and subsequent reduction of metal cations.…”

Designer Nanomaterials for the Production of Energy and High Value‐Added Chemicals

“…The SMNPs were found to be very stable to thermal treatment. Ar glow discharged plasma has also been employed to support Pt, Pd, Ag, and Au NPs on a range of supports including nonporous TiO 2 , γ -alumina, and H-ZSM-5 [35]. NPs were found to be homogeneously distributed on the surface of the support, being in the nanoscale range.…”