NiS2@V2O5/VS2 ternary heterojunction for a high-performance electrocatalyst in overall water splitting

Water splitting is regarded as an effective way to produce hydrogen energy to solve the energy crisis all over the world. However, the electrocatalysts suffer from expensive prices, high voltage, and sluggish kinetics. The heterojunction is composed of two semiconductors and can accelerate electron transfer by relying on interface engineering. Herein, we first prepare NiS2@V2O5/VS2 ternary heterojunction electrocatalyst, showing the low OER overpotential of 333 mV and HER overpotential of 216 mV at 10 mA cm−2, as well as good stability. Meanwhile, the NiS2@V2O5/VS2 heterojunction is assembled to the two-electrode system for overall water splitting, exhibiting a very low voltage value of 1.49 V, which is much superior to that of the benchmark RuO2//Pt/C system. The energy band calculation reveals the mechanism that the NiS2 and VS2 lower the Fermi level of V2O5, thus promoting the electrons transfer in the electrocatalytic reactions. Our work opens up a novel route for heterojunction application in the electrocatalytic field.