palladium black is a high surface area precipitated palladium powder used as an efficient heterogeneous catalyst in organic chemical reactions and fuel cells.
It is a member of the platinum group metals (PGM) along with platinum, rhodium, ruthenium and iridium. It is also used as a catalytic converter in automobiles, and is also found in dentistry, groundwater treatment and electronics.
A very soft ductile metallic element, Pd has the lowest density and melting point of the PGMs. It is stable in air, even at elevated temperatures, and shows no tarnishing when exposed to hydrogen sulfide atmospheres.
In addition, Pd is resistant to oxidation and has a high thermal conductivity. It is used as a catalyst in organic synthesis, the manufacture of sulfuric acid and in the separation of hydrogen from a mixture of gases.
Palladium is a very common component in dental alloys, especially those that contain silver and/or gold. It has been associated with histocompatibility problems in animal studies, but is considered to be inert by most dentists.
Granulomatous tissue reactions due to jewelry made from gold, silver, nickel and palladium are rare, but have been described. In one such case, a female patient developed nodular infiltrates after having been pierced with ear stickers containing palladium.
Exposure to palladium can be gained through exchange-traded funds that track palladium bullion, such as the Sprott Physical Platinum and Palladium Trust or Aberdeen Physical Palladium Shares. It can also be achieved by purchasing physical palladium bullion, which is more costly than ETFs but provides the same exposure to the metal.