Synthesis of γ-graphyne by mechanochemistry and its electronic structure

Abstract As a new member of the carbon family, γ-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 γ-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 γ-graphyne in terms of composition, morphology and lattice constant. The as-prepared γ-graphyne, which is composed of sp2-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 γ-graphyne from readily available precursors and presents many experimental parameters of γ-graphyne.