Acta Phys. -Chim. Sin. ›› 2018, Vol. 34 ›› Issue (9): 1080-1087.doi: 10.3866/PKU.WHXB201802262

Special Issue: 石墨炔

• ARTICLE • Previous Articles     Next Articles

Synthesis of Hydrogen Substituted Graphyne through Mechanochemistry and Its Electrocatalytic Properties

Jordan LEE1,Yong LI2,Jianing TANG1,3,Xiaoli CUI1,*()   

  1. 1 Department of Materials Science, Fudan University, Shanghai 200433, P.R.China
    2 Shanghai Institute of Space Power Sources, Shanghai 200245, P.R.China
    3 Department of Advanced Materials Science and Engineering, Imperial College London, London SW72AZ, Britain
  • Received:2018-02-03 Published:2018-04-09
  • Contact: Xiaoli CUI E-mail:xiaolicui@fudan.edu.cn
  • Supported by:
    National Natural Science Foundation of China(21273047);the Aerospace Science and Technology Innovation Fund of SAST, China(YF07050117F4051)

Abstract:

Since the successful synthesis of graphdiyne, graphynes have emerged as an active field in carbon materials research.Hydrogen-substituted graphyne, structurally similar to graphynes, is a kind of two-dimensional (2D) carbon-rich material composed of sp2-hybridized carbon and hydrogen from phenyl groups and sp-hybridized carbon from ethynyl linkages.The large pore size in the molecular structure of hydrogen-substituted graphyne aids the diffusion of ions and molecules.In this work, hydrogen-substituted graphyne was synthesized by a facile mechanochemical route.Calcium carbide (CaC2) was employed as the precursor of sp-hybridized carbon and 1, 3, 5 tribromobenzene (PhBr3) as that of sp2-hybridized carbon and hydrogen.Hydrogen-substituted graphyne was directly obtained via the cross-coupling reaction performed by ball milling under vacuum and the impurities were removed by dilute nitric acid and benzene.Mechanochemistry is a mature technology for the simple and high-yield synthesis of nanostructured materials.The composition of the as-prepared hydrogen-substituted graphyne was confirmed by Raman and 1H solid-state nuclear magnetic spectroscopies.Energy-dispersive X-ray (EDX) spectrum and X-ray diffraction (XRD) patterns indicated that the purity and crystallinity of the prepared samples are high, which was further confirmed by the corresponding selected area electron diffraction (SAED) patterns.Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images illustrated that samples had nanosheet structure with a layer-to-layer distance of 0.35 nm.However, owing to the lack of a substrate, the nanosheets reunite to form irregular microparticles, as shown in the scanning electron microscopy (SEM) images.Twin structure was found in the as-prepared samples, which might be relevant to the mechanochemical process.The samples were used to prepare electrodes for the photoelectrochemical and electrochemical catalytic analysis.The open circuit potential under chopped irradiation of the electrode showed that the as-prepared hydrogen-substituted graphyne was a p-type semiconductor.The band gap was calculated to be 2.30 eV by UV-Vis diffused reflectance (UV-Vis DRS) spectroscopy.The electrocatalytic properties of the sample were determined using a three-electrode cell in a neutral solution (Na2SO4, 0.5 mol·L−1).The onset overpotential for hydrogen evolution was −0.17 V; however, the Tafel slope was too large (1088.4 mV·dec−1), which restricted application in electrocatalytic hydrogen evolution.On the other hand, the overpotential for oxygen evolution reaction was only 0.04 V and the Tafel slope was 70.0 mV·dec−1, making applications in electrocatalytic oxygen evolution and photocatalysis possible.This strategy opens a new avenue for preparing graphyne with good electrochemical properties using readily available precursors under mild conditions.

Key words: Hydrogen substituted graphyne, Mechanochemistry, Semiconductor, Oxygen evolution reaction

MSC2000: 

  • O647