Formation of nano-crystalline C3N4 thin films on stainless steel from hexamethylenetetramine and urea using simple sol–gel method

•Formation of nano-crystalline C3N4 thin films with a low cost and simple sol–gel method•Uses of inexpensive materials, like steel, hexamethylenetetramine and urea•Repeatability of this method using different precursors for crystalline C3N4 thin films

Nano-crystalline C3N4 thin films have been deposited on stainless steel (SS) substrates from hexamethylenetetramine (HMTA) and urea separately using simple sol–gel method. For that purpose hot-dip coating processes were carried out. The coated specimens were annealed at 800 °C in N2. The samples were analyzed using field emission scanning electron microscopy, nanoindenter, X-ray photoelectron spectroscopy and X-ray diffraction. The deposits show C3N4 with clear hexagonal morphology and size range of 50–500 nm. The hardness values of the synthesized films show 2.74–4.35 times higher than that of SS. The hardness and Young's modulus of the films synthesized from HMTA show the highest values; 16.10 and 394.29 GPa, respectively. This significant achievement of the production of nano-crystalline C3N4 from inexpensive sources and simple methods at ambient pressure opens up a door for its low cost production on SS for a wide range of applications. Irrespective of the sources with different chemical structures we got similar product, which implies that different sources of carbon and nitrogen might be used with our methods of sol–gel deposition.