Hydrogen evolution was performed in KOH and H2SO4 electrolytes using α-Mo2C and γ-Mo2N synthesized by the ‘urea glass’ route. α-Mo2C shows excellent performance especially in KOH.

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.

Efficient synthetic routes are continuously pursued for graphene in order to implement its applications in different areas. However, direct conversion of simple monomers to graphene through polymerization in a scalable manner remains a major challenge for chemists. Herein, a molten-salt (MS) route for the synthesis of carbon nanostructures and graphene by controlled carbonization of glucose in molten metal chloride is reported. In this process, carbohydrate undergoes polymerization in the presence of strongly interacting ionic species, which leads to nanoporous carbon with amorphous nature and adjustable pore size. At a low precursor concentration, the process converts the sugar molecules (glucose) to rather pure few-layer graphenes. The MS-derived graphenes are strongly hydrophobic and exhibit remarkable selectivity and capacity for absorption of organics. The methodology described may open up a new avenue towards the synthesis and manipulation of carbon materials in liquid media.