Thermochemistry of nanoparticles on a substrate: Zinc oxide on amorphous silica

Crystalline samples of zinc oxide on a mesoporous amorphous silica substrate were prepared by 5 to 15 atomic layer deposition cycles with diethyl zinc and water at 150 °C. Samples were characterized by x-ray diffraction, thermogravimetry, and nitrogen adsorption–desorption isotherms. High-temperature oxide melt solution calorimetry and water adsorption calorimetry experiments were performed to measure surface enthalpy for crystalline ZnO particles supported on the substrate. The measured enthalpies 1.23 ± 0.35 and 2.07 ± 0.59 J/m² for hydrous and anhydrous surfaces, respectively, are in agreement with previously reported measurements for unsupported ZnO nanoparticles. Feasibility of thermochemical characterization of complex system of atomic layer deposition (ALD) prepared particles on a substrate was demonstrated.