Highly dispersed ZrO2/SiO2 and V2O5/ZrO2/SiO2 catalysts were successfully synthesized by the incipient wetness impregnation method. The surface structures of these catalysts in hydrated and dehydrated states were characterized by in situ Raman and UV−vis−near-infrared diffuse reflectance spectroscopies. Temperature-programmed reduction and methanol oxidation were employed as chemical probe reactions to examine the reducibility and reactivity/selectivity properties of these catalysts. These characterization techniques demonstrate that both zirconium oxide and vanadium oxide species are highly dispersed as two-dimensional metal oxide overlayers on the silica support. The spectroscopic results revealed that the surface vanadium oxide species on the highly dispersed ZrO2/SiO2 supports are predominantly isolated VO4 units [OV(O−support)3] in the dehydrated state and become polymerized vanadium oxide species upon hydration. The surface vanadium oxide species preferentially interact with the zirconium oxide species on the silica surface. The substitution of SiIV−O- by ZrIV−O- ligands significantly affects the chemical properties of the isolated VO4 units:  the reducibility of the surface vanadium oxide species increases, and the methanol oxidation turnover frequency (TOF) increases by 1−2 orders of magnitude relative to V2O5/SiO2. The present study demonstrates that the support effect, variation in the reactivity of supported metal oxide catalysts due to different oxide supports, essentially originates from the difference in oxygenated ligands around the active metal cations.

The effect of vanadium oxide loading on CeO 2 support for ethane oxidative dehydrogenation (ODH) is studied. Surface vanadia species are highly dispersed on CeO 2 . The interaction with surface vanadia species significantly changes the structural and reactive properties of ceria support. VO x /CeO 2 suffers an important change during ethane ODH due to a solid-state reaction between CeO 2 and surface vanadia species resulting in the formation of CeVO 4 . Such a solid-state reaction is promoted by high temperature, high vanadium loading, and reducing environments. Raman in situ temperature-programmed studies under reduction and oxidation conditions reveal that the catalytic cycle involves oxidation-reduction of the Ce 4+ T Ce 3+ species, while the V 5+ species remain stable.

CVD boron nitride films have been deposited at 800 °C from diborane, ammonia, and hydrogen gas mixtures, using different B2H6 flow rates. The effect of the [B2H6]/[NH3] ratio in the gas mixture on the structure, composition, and the stability of the layers in humid atmospheres has been studied. For low [B2H6]/[NH3] ratios (r ≤ 0.25), the deposition rate is low and some crystalline ordering in the deposit was detected. However, when ratios >0.25 are used, stable amorphous boron nitride films are deposited at deposition rates four times higher (160 nm min-1). The partially turbostratic boron nitride films, deposited at r ≤ 0.25, are unstable in humid atmospheres (80% moisture). The evolution of the unstable films was followed by infrared spectroscopy. It is observed that the turbostratic component in the film is rapidly attacked by the water molecules present in the atmosphere, giving rise finally to boron enrichment in the films. After this stage, the attack rate becomes slower, due to the higher stability of the amorphous component in the films.