Synthesis of γ-graphyne by mechanochemistry and its electronic structure

As a new member of the carbon family, gamma-graphyne has the advantages of high carriers mobility and semiconductor characteristic. In this work, a simple and high-yield route is proposed to synthesize monocrystalline gamma-graphyne by mechanochemistry. Energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy and corresponding selected area electron diffraction were performed to confirm the features of gamma-graphyne in terms of composition, morphology and lattice constant. The as-prepared gamma-graphyne, which is composed of sp-hybridized and sp-hybridized carbon, is a monocrystalline with a lattice constant of 0.69 nm. UV-vis diffused reflectance spectroscopy was measured for the resultant sample and its band gap energy is estimated to be 2.58 eV from the absorption edge. The sample exhibited p-type behavior which was confirmed by the negative slope in Mott-Schottky plots and the linear sweep voltammograms under light irradiation. The valence and conduction band positions are around +2.53 and -0.05 V (vs normal hydrogen electrode) respectively, calculating from the flat band potential and its band gap energy. This work provides a novel strategy for the synthesis of gamma-graphyne from readily available precursors and presents many experimental parameters of gamma-graphyne. (C) 2018 Elsevier Ltd. All rights reserved.