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 ⁴¹K⁺ ions obtained by time-of-flight secondary ion mass spectroscopy (TOF-SIMS). The intensity images of ⁴¹K⁺ 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.

通过使用氢氧化钾 (KOH) 水溶液（KOH 处理）的湿化学工艺证明了多层石墨烯的钾 (K) 掺杂。从通过飞行时间二次离子质谱法 (TOF-SIMS) 获得的⁴¹ K ⁺离子的深度剖面证实了沿堆叠方向存在 K 原子。⁴¹ K ⁺的强度图像TOF-SIMS 获得的离子表明 K 原子存在于整个区域。对于 KOH 处理的多层石墨烯，通过 X 射线衍射 (XRD) 没有获得由于石墨烯层之间的 K 嵌入导致的峰；在拉曼光谱中，没有观察到 G 带峰的分裂和 2D 带峰的消失。XRD 或拉曼结果均未确定石墨插层化合物结构。然而，拉曼光谱中 G 带峰位置的上移表明 K 原子掺杂在石墨烯中。X 射线光电子能谱碳 1s 光谱表明 KOH 处理导致石墨烯边缘和/或域的 K 终止。此外，与原始石墨烯的 C1s 峰相比，C1s 肩峰出现在结合能高 1 eV 处。温度相关的电导率测量结果表明，KOH 处理提高了多层石墨烯的电导率。此外，电导率随着温度的升高而增加，这可以用带重叠来解释。