Graphene and its composite hydrogels with interconnected three-dimensional (3D) structure have raised continuous attention in energy storage. Herein, we describe a simple hydrothermal strategy to synthesize 3D CoS/graphene composite hydrogel (CGH), which contains the reduction of GO sheets and anchoring of CoS nanoparticles on graphene sheets. The formed special 3D structure endows this composite with high electrochemical performance. Remarkably, the obtained 3D CGH exhibits high specific capacitance (Cs) of 564 F g−1 at a current density of 1 A g−1 (about 1.3 times higher than pure CoS), superior rate capability and high stability. It is worth mentioning that this methodology is readily adaptable to decorating CoS nanoparticles onto graphene sheets and may be extended to the preparation of other pseudocapacitive materials based on graphene hydrogels for electrochemical applications.

Three-dimensional (3D) graphene-based composite materials have attracted increasing attention, owing to their specific surface area, high conductivity and electronic interactions. Here, we report a convenient route to fabricate a 3D Co3O4/Graphene Hydrogel (CGH) composite as an electrode material for supercapacitors. Utilizing the gelation of a graphene oxide dispersion enables the anchoring of Co3O4 nanoparticles on the graphene sheet surfaces and formation of the hydrogel simultaneously. Remarkably, the spherical Co3O4 particles can serve as spacers to keep the neighboring graphene sheets separated. The CGH exhibits a high specific capacitance (Cs) of 757.5 F g(-1) at a current density of 0.5 A g(-1), indicating its potential application as an electrode material for supercapacitors.

Graphitic carbon nitride (g-C 3 N 4 ), characterized with a suitable bandgap, has aroused great interest as a robust and efficient catalyst for solar energy utilization. Herein, we introduce a new strategy to fabricate a three-dimensional (3D) porous g-C 3 N 4 by a facile NaCl-assisted ball-milling strategy. The porous structureinduced advantages, such as a higher specific surface area, more efficient charge separation, and faster electron-transfer efficiency, enable the 3D porous g-C 3 N 4 to achieve impressive properties as a bifunctional catalyst for both photocatalytic hydrogen evolution and electrocatalytic oxygen evolution reaction (OER). As a result, the 3D porous g-C 3 N 4 exhibits a hydrogen evolution rate of 598 μmol h −1 g −1 with an apparent quantum yield of 3.31% at 420 nm for photocatalytic H 2 generation, which is much higher than that of the bulk g-C 3 N 4 . Simultaneously, the porous g-C 3 N 4 also presents an attractive OER performance with a low onset potential of 1.47 V (vs reversible hydrogen electrode) in an alkaline electrolyte after rational cobalt-doping. Accordingly, the NaCl-assisted ball-milling strategy paves the way to the rational design of a controllable porous structure.

The three-dimensional cobalt sulfides/graphene hydrogel nanocomposites were prepared via a one-step method in a water–isopropanol system with enhanced electrochemical performance.

Ni(OH)2/graphene composite hydrogels are successfully prepared with the Ni(OH)2 nanoplates uniformly grown on graphene sheets in situ.