Photoluminescence of (boron and nitrogen)-rich BCN compounds pyrolysed from precursor

C₃N₆H₆ (H₃BO₃)₂ precursor was synthesized with C₃N₆H₆ and H₃BO₃ as raw materials in aqueous solution, which was followed by pyrolysis at high temperature in flowing N₂ atmosphere to prepare (boron and nitrogen)-rich BCN compounds. The pyrolysis products were characterized by FTIR, XRD, XPS, SEM and HRTEM. The room-temperature photoluminescence(PL) spectra of the pyrolysis products were measured by fluorescence spectrometry. Effect of pyrolysis temperature on the pyrolysis products and their photoluminescence were investigated. The results indicate that (boron and nitrogen)-rich BCN compounds with turbostratic graphite structure can be obtained when the pyrolysis temperature is above 1000°C. With the increase of pyrolysis temperature, the contents of B and N in the BCN compounds increase whereas the content of C decreases. These BCN compounds show bar-like or fibrous morphologies similar to the precursor. HRTEM analysis reveals that these BCN compounds are composed of interweaved nanofibers with average diameter of ca. 2 nm. PL results indicate that these BCN compounds are semiconductors with two strong and broad PL peaks centered at 340-450 nm and 670-705 nm. With the increase of pyrolysis temperature, the wavelength of the peak centered in the shorter wavelength range decreases due to the variation of the chemical composition.