Defect states induced luminescence and electrochemical studies of boron carbon nitride nanosheets

Thermo-chemicaaly synthesized BCN nanosheets for photoluminescence and electrochemical properties. [Display omitted] •Synthesis of hexagonal BCN nanosheets via novel one step solvothermal method.•The role of sp2 domains of carbon-based defect states on optical properties of BCN.•Ultraviolet and Visible region emission due to band-to-band transitions, and defect states of BCN respectively.•Detailed electrochemical analysis of BCN for HER applications. A single-step thermochemical synthesis route for boron carbon nitride (BCN) has been reported in this work. X-ray photoelectron spectroscopy (XPS) shows that B, C, and N atoms are atomically intermixed with the dominance of graphite and BN domains. In Fourier transform infrared spectroscopy, a broad band at 1521 cm−1 (sp2 CN) indicates the presence of defect states comparable to the presence of πP (CN) plasmon loss peak in XPS. The role of defect states in the optical properties of BCN has been analyzed using UV–Visible and photoluminescence (PL) spectroscopy. PL shows a defect states induced broad emission band (2–2.9 eV) from the sp2 domain and a sharp peak at 3.64 eV due to band to band transitions of the direct band of BCN. Carbon played a significant role in the formation of deep levels responsible for the carrier trapping and recombination process. Defect induced emission in the ultraviolet and visible region makes this material suitable for optoelectronic, nanoelectronics, catalytic applications, etc. Hydrogen evolution reaction (HER) studies also show high performance due to presence of these defect states. The improved stability makes the material vital to be explored as electrode material in batteries and supercapacitors.