Formation of Nanowindow between Graphene Oxide and Carbon Nanohorn Assisted by Metal Ions

Abstract

This study presents a novel nanostructured material formed by inserting oxidized carbon nanohorns (CNHox) between layered graphene oxide (GO) nanosheets using metal ions (M) from nitrate as intermediates. The resulting GO–CNHox-M structure effectively mitigated interlayer aggregation of the GO nanosheets. This insertion strategy promoted the formation of nanowindows on the surface of the GO sheets and larger mesopores between the GO nanosheets, improving material porosity. Characterization revealed successful CNHox insertion, which increased interlayer spacing and reduced GO stacking. The GO–CNHox-Ca exhibited a significantly higher specific surface area (SSA) and pore volume than pure GO, with values of 374 m² g^–1 and 0.36 mL g^–1, respectively. The GO–CNHox-K composite also exhibited a well-developed pore structure with an SSA of 271 m² g^–1 and pore volume of 0.26 mL g^–1. These findings demonstrate that Ca²⁺ or K⁺ ions effectively link GO and CNHox, validating the success of this insertion approach in reducing GO aggregation. Metal ions played a crucial role in the insertion process by facilitating electrostatic interactions and coordination bonds between GO and CNHox. This study provides new insights into reducing GO agglomeration and expanding the application of GO-based materials.