Facile synthesis of NiS2–MoS2 heterostructured nanoflowers for enhanced overall water splitting performance

Although MoS2 materials are known as the efficient catalysts in acidic solution toward hydrogen evolution reaction, it remains a challenging issue for improving catalytic activity of MoS2 materials toward electrochemical splitting of water in alkaline solution. Herein, we developed NiS2–MoS2 heterostructured nanoflowers with 430–810 nm in diameter using a simple one-pot hydrothermal method. The resultant catalysts required the potential of 1.5 V to afford 10 mA/cm2 toward the oxygen evolution reaction, lower than that of MoS2 nanoflowers. Hydrogen evolution reaction was enhanced by the introduction of Ni into MoS2 nanoflowers with 194 mV at the current density of 10 mA/cm2. Moreover, the cell assembled by the NiS2–MoS2 heterostructured nanoflowers could drive the voltage of 1.67 V at 10 mA/cm2 using two-electrode system in 1.0 mol/L KOH solution toward overall water splitting. Structure-controlled synthesis of NiS2–MoS2 nanoflowers, directing the construction of heterointerfaces with the exposure of the abundant active sites, greatly altered the electron distribution due to synergistic effect between Ni–S and Mo–S. Due to the unique structure, NiS2–MoS2 heterostructured nanoflowers could effectively catalyze overall water splitting. NiS2–MoS2 heterostructured nanoflowers exhibited the enhanced overall water splitting activity in alkaline media due to more positive charges for Ni atoms and more surplus electrons for S.