3D isotropic hole-in-platelet graphene hydrogels with high surface area and fast mass transfer ability as efficient adsorbents

Abstract

Abstract Integrating the advantages in adsorption and solving the problems of agglomeration and reclamation of 2D graphene, 3D graphene have been regarded as the idea adsorbents for next generation. Nerveless, the mediocre adsorption capacity and comparatively long adsorption time are the key bottlenecks hindering the practical implementations of graphene monolith. Here, we displayed the rational design of 3D graphene hydrogels with isotropic microstructure and in-platelet holes (3D NGH). The isotropic microstructure induced by reducing the size of graphene oxide (GO) lamellae effectively reduced the overlap ratio of graphene and rendered NGH an desired specific surface area (SSA) of 437.07 m2 g−1. Benefiting from that, NGH exhibited an ultrahigh maximal adsorption capacity of 1120.28 mg g−1, where methylene blue (MB) was chosen as the verifiable pollutant. Meanwhile, the in-platelet holes of NGH obtained by simply HNO3 etching significantly improved the mass transfer ability and adsorption rate of SGH (about a fivefold increase from 2.235 × 10−5 to 12.670 × 10−5 g mg−1 min−1). This facile and scalable preparation tackled the two critical issues of 3D graphene adsorbents simultaneously and laid a valuable groundwork for future development in constructing graphene-based composite materials for environmental or energy applications.