Resolving Precursor Deligation, Surface Species Evolution, and Nanoparticle Nucleation during Palladium Atomic Layer Deposition

The synthesis of highly dispersed palladium nanoparticles on TiO 2 surfaces from palladium hexafluoroacetylacetonate (Pd(hfac) 2 ) was investigated using in situ infrared (IR) spectroscopy, in situ X-ray absorption spectroscopy (XAS), and in situ pair distribution function (PDF) measurements under practical atomic layer deposition conditions. Residual surface chlorine was found to directly participate in the transformation of organometallic compounds to nanoparticles. Deligation of the Pd(hfac) 2, evolution of the surface species, and nucleation of the Pd nanoparticles were precisely resolved. This knowledge can help direct the future design of advanced heterogeneous catalysts from organometallic compounds.