GRAPHITIC CARBON NITRIDE: FROM BULK POWDER TO THIN FLAKES

Graphitic carbon nitride (g-C₃N₄) have attracted tremendous attention in the scientific community as a promising material for catalysis and photo-catalysis applications. It presents a graphene-like 2D structure, composed of heptazine units. The pioneering work on graphene led to an explosion in the amount of research in other 2D materials, due to their unique physical and chemical properties which are highly influenced by the number of layers, their registry, chemical composition, etc. Hence, we present here our attempts to synthesize and characterize crystalline g-C₃N₄ 2D thin flakes. We highlight an available pathway to prepare graphitic carbon nitride powder and thin flakes by thermal decomposition of melamine (C₃H₆N₆). X-ray diffraction (XRD) patterns and Solid-state NMR strongly indicate that the synthesized sample has heptazine building blocks, which corresponds to the g-C₃N₄ structure. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) morphologies indicate that the product is poly-crystalline and has a layered structure. Atomic force microscope (AFM) measurements indicate that the thickness of the thin flakes is 10-30 nm. The chemical bonding of the samples has been investigated by X-ray photoelectron spectroscopy (XPS). Fourier transform infrared spectroscopy (FTIR) and UV-Raman spectroscopy will be discussed and their optical properties, interrogated by Photoluminescence (PL) measurements, reviewed. The results are coherent with each other and support that the structure of the obtained g-C₃N₄ material consist of heptazine units.