The size control of nanowindows on the graphene walls is indispensable to develop innovative adsorption and separation technologies. As single wall carbon nanohorn (SWCNH) consists of graphene wall, the permeation of ions through the nanowindows can be evaluated with adsorption measurement. We regulated the nanowindow size by use of mild oxidation at 473–523 K for 20–70 h. The explicit low pressure adsorption hysteresis was observed in the N₂ adsorption isotherms of thus-oxidized SWCNHs, suggesting the window size of 0.3–0.4 nm. Moreover, the aqueous phase adsorption measurement for Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺ indicates that the nanowindow size is smaller than about 0.37 nm, being close to the estimated size from N₂ adsorption.

石墨烯壁上纳米窗口的尺寸控制对于开发创新的吸附和分离技术必不可少。由于单壁碳纳米角（SWCNH）由石墨烯壁组成，因此可以通过吸附测量来评估离子通过纳米窗口的渗透。我们通过在473–523 K下温和氧化20–70 h来调节纳米窗口的大小。在如此氧化的SWCNHs的N ₂吸附等温线中观察到明显的低压吸附滞后，表明窗口大小为0.3–0.4 nm。此外，对Li ⁺，Na ⁺，K ⁺，Rb ⁺和Cs ⁺的水相吸附测量表明纳米窗口的尺寸小于约0.37 nm，接近于N ₂吸附估算的尺寸。