Fine Nanophased ZnO:Ru and ZnO:Pt Powder Synthesis Through Aerosols

摘要

Pt/Ru-doped ZnO nanophase particles were synthesized using ultrasonic spray pyrolysis. Particles were obtained through decomposition of zinc nitrate and newly developed Pt(Ⅳ) and Ru(Ⅲ) complexes. The particle morphology, phase composition and chemical structure were revealed in accordance to various analysis methods (XRD, DSC, SEM/EDS, TEM) and discussed in terms of precursor chemistry and process parameters. The shape of DSC curves, indicating two exothermic effects above 600℃ in both ZnO:Ru and ZnO:Pt, gave an indication of irreversible structural changes and high reactivity of as-prepared powders. The hexagonal wurtzite-type ZnO phase was revealed in both powdered samples. Small content of an intermediate Zn_5(NO_3)_2(OH)_8·2H_2O and cubic Zn_2PtO_4 phase were detected in the Pt-doped ZnO particles. Structural refinements, performed by Koalariet-XFit, suggest the composite internal particle structure composed of primary particles sized less than 100 nm. The estimated values for the unit cell parameters and Zn-0 bond lengths imply noble metal ions incorporation into ZnO matrix interstitially, probably in octahedral interstitial environment. It has been shown that different particle growing morphologies (either spheroidally or pyramidally shaped) were influenced by the precursor chemistry, processing parameters and the presence of noble metal ions. Among the many parameters, attaining of the particle shape uniformity and homogeneous distribution of the noble metal cations in as-prepared particles are regarded as the most important factors for dominating microstructure evolution.