Abstract
Photo-catalytic deposition of fine Pd particles on diamond particles and subsequent electroless coating with Ni were studied, Fine Pd particles could be deposited by photo-irradiation in spite of the smaller energy of incident light (<3.9eV) than Eg of diamond (5.47eV). They have higher activity for the electroless coating of Ni than those deposited by means of the usual 2-liquid type sensitizing method. The resulting Ni layer was uniform and adhered closely to diamond particles. For good distribution and adherence of the Pd deposits, surface pre-treatment was very effective. Ethanol and i-propanol were suitable as a reducing agent for dense deposition, and the reaction temperature of 35°C was best. The density of the Pd particles seems to be determined by reduction of Pd2+ ion with an intermediate alcohol radical rather than by that with the photo-excited electron.
