Open AccessSynthesis and characterization of potassium-doped multilayer graphene prepared by wet process using potassium hydroxide
Author(s) -
Tomoaki Masuzawa,
Yuki Okigawa,
Shuichi Ogawa,
Yuji Takakuwa,
Kazuto Hatakeyama,
Takatoshi Yamada
Publication year - 2021
Publication title -
nano express
Language(s) - English
Resource type - Journals
ISSN - 2632-959X
DOI - 10.1088/2632-959x/ac1454
Subject(s) - graphene , raman spectroscopy , materials science , intercalation (chemistry) , analytical chemistry (journal) , potassium hydroxide , x ray photoelectron spectroscopy , conductivity , graphite , potassium , doping , inorganic chemistry , chemistry , nanotechnology , chemical engineering , organic chemistry , optics , optoelectronics , engineering , metallurgy , physics , composite material
Potassium (K) doping of multilayer graphene was demonstrated by means of a wet chemical process using potassium hydroxide (KOH) aqueous solution (KOH treatment). The presence of K atoms along the stacking direction was confirmed from depth profiles of 41 K + ions obtained by time-of-flight secondary ion mass spectroscopy (TOF-SIMS). The intensity images of 41 K + ions obtained by TOF-SIMS suggested that the K atoms existed throughout the whole area. For the KOH-treated multilayer graphene, no peak due to K intercalation between graphene layers was obtained by x-ray diffraction (XRD); in Raman spectra, splitting of the G-band peak and disappearance of the 2D-band peak were not observed. A graphite intercalation compound structure was not determined by either XRD or Raman results. However, the up-shift in the G-band peak position in the Raman spectra suggested that K atoms were doped in the graphene. X-ray photoelectron spectroscopy carbon 1s spectra implied that KOH treatment resulted in K-termination at the edges and/or domains of graphene. In addition, a C1s shoulder peak appeared at 1 eV higher binding energy compared to the C1s peak of pristine graphene. Temperature-dependent conductivity measurement results indicated that the conductivity of multilayer graphene was increased by KOH treatment. In addition, the conductivity increased with increasing temperature, which could be explained by band overlap.