C3N4:: Dream or reality?<ΤΒ> Solvothermal synthesis as macroscopic samples of the C3N4 graphitic form

In order to prepare C3N4 as macroscopic sample, two synthesis attempts of the graphitic variety were carried out. The first consists on the condensation of melamine and cyanuric chloride (P = 130 MPa, T = 250 degrees C) with triethylamine acting as solvent in supercritical conditions. The second one consists on the pyrolysis of melamine (P = 2.5 GPa, T = 800 degrees C) in presence of hydrazine. The two routes led to a graphite-like carbon nitride, nevertheless, the first product is poorly crystallized and contains a larger amount of hydrogen as NHx due to a partial condensation. Several analysis (XRD, SEM, TEM, FTIR, XPS, EELS) reveal that the brown black solid issued from the route 2 presents a bidimensional honey-type structure close to those expected for the theoretical g-C3N4. This synthesis represents a first step in the C3N4 synthesis and its study as macroscopic sample. (C) 2000 Kluwer Academic Publishers.