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

Abstract

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°C) with triethylamine acting as solvent in supercritical conditions. The second one consists on the pyrolysis of melamine (P = 2.5 GPa, T = 800°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 NH_x 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.