posted on 2025-05-15, 18:52authored byFan Wu, Xueyan Chen, Hong Zhang, Yue Zhao
The flexible assembly properties of GO nanosheets in
a solution
system enable them to be effectively constructed into novel and ordered
macroscopic material structures. Among various 3D structures, graphene
hollow spheres (GHSs) have attracted great attention due to their
wide application potential such as compounds in catalyst carriers
and electrode materials. In this paper, a novel template-free self-assembly
method was proposed to produce GHSs with better spherical shape, thinner
walls, and sizes at the microscale. A bubble generator was used to
introduce uniform and numerous bubbles in the GO sheets, inducing
curling and wrinkling around the GO/water interface. The structural
evolution of the GO dispersion during hydrothermal and drying processes
was investigated after different treatments. It was found that the
acidification treatment promotes the hydrothermal reduction reaction
of GO sheets, which leads to the reduction of their oxygen content
and the decrease of their interlayer spacing (d-spacing).
Furthermore, the micro- and nanobubble treatment contributes to the
homogeneous dispersion of GO sheets and induces their curling behavior.
When the hydrothermal reaction products were dried at 100 °C,
the release of solvent and gas from the GO sheets was inhibited by
the small d-spacing, leading to the expansion of
the surface layers and the formation of graphene hollow microspheres.
The detailed formation mechanism of graphene hollow microspheres was
verified by molecular dynamics (MD) simulations of water molecule
permeation behavior with different graphene layer spaces. The findings
of this study will contribute to the structural design of graphene-based
materials.