Reduction of PtO₂ Powders (Adam's Catalyst) under Electron Beam Irradiation

Under certain conditions, noble metals can form relatively stable oxides. For platinum, for example, the oxide phases include PtO, a-PtO 2 , b-PtO 2 , Pt 3 O 4 , and Pt 3 O 8 ; these platinum oxide phases possess unique catalytic, electrical, or optical properties. The platinum dioxide powders, also called the Adam's catalyst, have been used extensively as a catalyst for hydrogenation reactions. The Adam's catalyst consists mostly of crystalline a-PtO 2 phase. Platinum dioxide decomposes upon heating into pure Pt at temperatures > 500C and can be easily reduced by carbon monoxide, hydrogen, or other reducing agents. The Adam's catalyst has a surface area of about 80 m 2 /gm; it usually consists of flakes, platelets, powders, and nano-ribbons. In addition to be an important hydrogenation catalyst, platinum oxide films also find applications in microelectronics, chemical sensors, optical switches, and passivation of high-Tc superconductors. Surprisingly, however, there is not much study on the nanostructure of Adam's catalyst or platinum oxide films.