Graphene Quantum Dots Induced NiCo2S4 as an Efficient Electrocatalyst for Hydrogen Harvest

We made an efficient electrocatalyst for hydrogen harvest, with an overpotential as low as 0.131V to achieve a current density of 10 mA/cm
²
. The morphology of the material was extremely delicate: branches on the nanowire, and smaller twigs on the branches, such that the specific surface area was greatly enlarged. The two-step hydrothermal process is easily accessible. The improved performance of GQD/NiCo
₂
S
₄
should mainly be ascribed to graphene quantum dots (GQDs), which induce morphology change of NiCo
₂
S
₄
nanowires. The delicate morphology serves as a buffer for volume change, and also a reservoir for electrolytes to transport protons [1]. In the meaning time, GQDs inherit excellent properties from both graphene and quantum dots, improving conductivity. Moreover, the addition of GQDs creates numerous defects in both the basal and edge planes for the diffusion of protons and thus help overcome the sluggish redox kinetics of the electrode, leading to improved overall performances [2].