Chemical Fluid Deposition: Reactive Deposition of Platinum Metal from Carbon Dioxide Solution

Reduction of dimethyl(cyclooctadiene)platinum(II) (CODPtMe2) with hydrogen in supercritical carbon dioxide solution at 80 °C yields continuous metal films on solid inorganic and polymer substrates and discreet metal clusters within 200 nm pores of an aluminum oxide membrane. X-ray photoelectron spectroscopy indicates the deposited films are free of ligand-derived contamination and are of comparable purity to those deposited by chemical vapor deposition (CVD) using the identical precursor at 250 °C. The solubility of CODPtMe2 and its ligand-derived reduction products (cyclooctane and methane) in CO2 at the deposition conditions obviates precursor volatility requirements associated with CVD and enhances purity via facilitated desorption of the organic byproducts from the nascent metal surface. The discovery that the reduction of organometallic compounds proceeds cleanly in CO2 is the basis for chemical fluid deposition (CFD), a new, generally useful approach to the low-temperature metallization of polymers and inorganic solids.