Conventional carbon materials cannot combine high density and high porosity, which are required in many applications, typically for energy storage under a limited space. A novel highly dense yet porous carbon has previously been produced from a three-dimensional (3D) reduced graphene oxide (r-GO) hydrogel by evaporation-induced drying. Here the mechanism of such a network shrinkage in r-GO hydrogel is specifically illustrated by the use of water and 1,4-dioxane, which have a sole difference in surface tension. As a result, the surface tension of the evaporating solvent determines the capillary forces in the nanochannels, which causes shrinkage of the r-GO network. More promisingly, the selection of a solvent with a known surface tension can precisely tune the microstructure associated with the density and porosity of the resulting porous carbon, rendering the porous carbon materials great potential in practical devices with high volumetric performance.

常规的碳材料不能兼具高密度和高孔隙率，而这在许多应用中通常是在有限空间内进行能量存储所必需的。先前已经通过蒸发诱导干燥从三维（3D）还原氧化石墨烯（r-GO）水凝胶生产了一种新型的高密度而多孔的碳。在这里，r-GO水凝胶中这种网络收缩的机理通过使用水和1,4-二恶烷来具体说明，它们在表面张力上有唯一的区别。结果，蒸发溶剂的表面张力决定了纳米通道中的毛细作用力，这导致r-GO网络收缩。更有希望的是，选择具有已知表面张力的溶剂可以精确地调节与所得多孔碳的密度和孔隙率相关的微观结构，