Nanostructured membrane structures have been fabricated by a combination of anodic aluminum oxidation (AAO) and atomic layer deposition (ALD) for use as platforms for the synthesis of highly uniform heterogeneous catalysts. The ALD method makes it possible to control pore diameters on the Angstrom scale even when the overall pore diameter is 10's to 100's of nanometers. AAO membranes imbedded in an aluminum sealing ring have been tested for flow properties and found to follow Knudsen diffusion behavior. Vanadia-coated membranes have been tested for the catalytic oxidative dehydrogenation of cyclohexane and show improved selectivity at the same conversion compared to conventional powdered alumina supported vanadia catalysts.

Formation of copper nanoparticles on zinc oxide (ZnO) powder is studied using a common chemical vapor deposition precursor, copper hexafluoroacetylacetonate vinyl trimethyl silane, Cu(hfac)(VTMS). This process is investigated by high-vacuum Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The growth was found to be promoted by exposing ZnO powder to the gas-phase water, and the intensity of the hydroxyl groups stretching signatures decreases after the powder is exposed to the copper deposition precursor. Vibrational spectroscopy results support the reaction on both polar and (101̅ 0) surfaces of the powder, and XPS confirms that the copper deposition takes place and identifies Cu(I) species as the main copper species on the surface of ZnO powder. The mechanism of the reaction includes the elimination of hfac ligand that reacts with surface hydrogen present in hydroxyl groups, and this surface-limited process stops when the surface runs out of available hydrogen. SEM is used to visualize the formation of copper-containing nanoparticles on ZnO(101̅ 0) and ZnO(0001̅ ) surfaces and defects. The mechanism for the initial stages of the deposition is proposed based on the computational investigation consistent with the experimental results. This general approach can be used to design a range of copper catalysts supported on ZnO with a high degree of control over the amount of copper deposited and the desired size distribution of the nanoparticles produced.

A variety of surface processes require removal or replacement of surface-bound chemical functional groups to achieve the properties required by a specific application. In the case of ZnO powder, a number of applications require manipulation of surface-bound species including ethoxy, acetoxy, acetylacetate, or 1,1,1,5,5,5-hexafluoroacetylacetate. The displacement of the surface species formed by these compounds on ZnO powder surfaces by a gas-phase reagent is described by a model that takes into account stability of surface species predicted by density functional theory and the strength of binding of the second layer on top of the first, provided by the ΔH of sublimation. This simple model is tested by infrared spectroscopy following the adsorption of one compound and its displacement by the other. A correlation between the enthalpic driving force and the percentage of the displaced species observed experimentally is found. This simple approach can be improved and generalized further to include other surface-bound species and other materials.

The thermal chemistry of β-diketones underlies a number of catalytic processes related both to the catalytic reactions yielding commodity chemicals and to the production of supported transition metal catalysts themselves. The mechanisms of decomposition during thermal transformation of three β-diketones, acetylacetone (acacH), 1,1,1-trifluoroacetylacetone (tfacH), and 1,1,1,5,5,5-hexafluoroacetylacetone (hfacH), were studied on ZnO powder surface using Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Density functional theory (DFT) computational investigation. The initial O-H dissociation leads to the formation of corresponding β-diketonates in all the cases investigated. These diketonates are important surface intermediates that can be generated in a controlled manner in these experiments. The presence on the C-CF3 entity determines the preferred thermal decomposition pathways, as the C-C bond in this group starts to react with a surface of ZnO around 400 K, followed by immediate decomposition of the resulting CF3 group. Above 600 K, the presence of the CF3-substituent leads to the formation of ketene-like structures observed by vibrational spectroscopy. The reaction mechanisms examined with the help of DFT calculations are correlated with vibrational signatures of the species produced and with the F-containing species recorded by XPS.

Supported nanoparticulate materials have a variety of uses, from energy storage to catalysis. In preparing such materials, precision control can often be achieved by applying chemical deposition methods. However, ligand removal following the initial deposition presents a substantial challenge because of potential surface contamination. Traditional approaches normally include multistep processing and require a substantial thermal budget. Using transmetalation chemistry, it is possible to circumvent both disadvantages and prepare chemically reactive copper nanoparticles supported on a commercially available ZnO powder material by metal-organic vapor copper deposition followed by very mild annealing to 350 K. The self-limiting copper deposition reaction is used to demonstrate the utility of this approach for hexafluoroacetylacetonate-copper-vinyltrimethylsilane, Cu(hfac)VTMS, reacting with ZnO. The low-temperature transmetalation is confirmed by a combination of spectroscopic studies. Model density functional theory calculations are consistent with a thermodynamic driving force for the process.