(24,25) To deposit ternary BCN thin films, we used the vapor deposition polymerization method previously reported for the synthesis of carbon nitride materials. The activation of symmetric bending of the triazine ring at 1492 cm –1 and an appearance of new peaks of B–OH bending in melamine diborate at 12 cm –1 is found after cocrystallization, indicating that melamine formed a hydrogen-bonded network structure with boric acid. Furthermore, two new peaks at 35 cm –1 are attributed to −NH 2 and −OH stretching. As shown in Fourier-transform infrared (FT-IR) spectra ( Figure 1b), a broad absorption in the −OH and −NH 2 range (3700–2700 cm –1) shows that supramolecular hydrogen-bonded network formation has taken place. (22,23) Indeed, when a solution of boric acid is added to a melamine dispersion in water at 100 ☌, gelation takes place by forming a cocrystal ( Figure 1a). (21)Īs previously reported by Roy et al., melamine forms a cocrystal with boric acid by forming hydrogen-bonding network structure in the monoclinic system P2 1/ c, thus making it a possible single-source precursor for ternary boron carbon nitride thin films deposition. used a thermal catalytic method to deposit BCN thin film on a copper substrate from methane and ammonia–borane as gaseous coprecursors at 900–1000 ☌, leading to a demixed-island graphene–boron nitride composite with tunable band gap. More recently, inspired by synthetic methods of graphene, Ci et al. (20) They found that boron, carbon, and nitrogen were successfully incorporated in the final material structure, showing XPS spectra different than the spectra of a mixture of graphite and BN, proving in that way that all the elements were effectively incorporated into the material. They used a mixture of three gaseous precursors, that is, boron trichloride, acetylene, and ammonia in the temperature range of 400–700 ☌. (19) One of the first attempts to synthesize BCN thin films by chemical methods was reported by Kaner et al. Many attempts on the synthesis of BCN thin films have been reported, employing techniques such as ion-beam-assisted, pulsed laser deposition, radio frequency (RF)/direct current (DC) sputtering, and chemical vapor deposition (CVD) techniques, with a single-source precursor or different boron-, carbon-, and nitrogen-containing precursors. (8) The extreme of nitrogen introduction in a graphitic structure leads to carbon nitride (CN), a mid band gap semiconductor with the ideal formula C 3N 4, which has attracted much attention in the past decade, especially for photocatalysis and very recently also for optical and optoelectronic applications. (7) Increasing further the nitrogen content allows for creating a wide range of carbon- and nitrogen-based organic frameworks with tunable properties, of great interest for a wide range of applications, such as electrochemical energy storage and photoelectrocatalysis. (4−6) With appropriate nitrogen insertion in the carbon structure, the electron density at the Fermi level can be increased, the valence band lowered (more positive with respect to the standard hydrogen electrode), so the material becomes more stable upon oxidation. (2,3) Nitrogen doping seems to be remarkably simple and was proven to increase electrical conductivity by modification of the electronic structure. Among others, graphene, graphite, porous carbon, carbon nanotubes, and fullerenes were modified by substituting carbon with other nonmetallic elements such as boron, nitrogen, phosphorus, and sulfur, and many reports also describe codoping. Substitutional doping with heteroatoms into various carbon materials to replace carbon positions has been reported to even expand the property space.