A simple, inexpensive, and versatile route for the synthesis of metal nitrides and carbides (such as Mo2N, Mo2C, W2N and WC) nanoparticles was set up. For the first time, metal carbides were obtained using urea as carbon-source. MoCl5 and WCl4 are in a first step contacted with alcohols and an appropriate amount of urea to form a polymer-like, glassy phase, which acts as the starting product for further conversions. Just by heating this phase it was possible to prepare either molybdenum and tungsten nitrides or carbides simply by changing the metal precursor/urea molar ratio. In this procedure, urea plays a double role as a nitrogen/carbon source and stabilizing agent (necessary for the nanoparticle dispersion). Molybdenum and tungsten nitride and carbides synthesized are almost pure and highly crystalline. Sizes estimated by WAXS range around 20 and 4 nm in diameter for Mo and W nitrides or carbides, respectively. The specific surface area was found between 10 and 80 m2/g, depending on the metal and the initial ratio of metal precursor to urea.

An easy way to produce several metal nitrides and metal carbides at relatively low temperature (800°C) using simple and mainly nontoxic precursor is presented. The procedure has been shown to be rather general and it was possible to synthesize TiN, VN, NbN, GaN, Mo 2 N, W 2 N, CrN, NbC(N), TiC(N), WC, Mo 2 C, and Cr 3 C 2 nanoparticles using urea or close derivatives as both nitrogen or carbon source and the growth controlling system. In every case, a homogeneous gel-like starting product has been formed that is converted by calcination into the corresponding metal nitride or metal carbide (including mixed species), without any preliminary treatments or further purifications. Samples were characterized by XRD, TEM, SEM, EA, and BET, and the products were shown to be well-defined and rather homogeneous.

A concept is shown to fabricate mesoporous ceria thin films with a crystalline framework and a bimodal pore size distribution by evaporation-induced self-assembly followed by a suitable temperature treatment and template removal strategy. The use of a suitable block copolymer ((CH 2 CH 2 CH 2 (CH)CH 2 CH 3 ) 79 (OCH 2 -CH 2 ) 89 OH), "KLE") and an ionic liquid template (leading to pores 3 nm in diameter) generated a bimodal pore system of deformed spherical mesopores of ca. 6 nm × 16 nm with the smaller pores being located in the matrix between the larger ones. The porosity was studied by a combination of quantitative SAXS analysis, physisorption, AFM, and TEM, introducing a general methodology for a quantitative structural characterization of such films.