Three-dimensional VOx/NiS/NF nanosheets as efficient electrocatalyst for oxygen evolution reaction

Developing effective and robust electrocatalysts that are applicable for intense conditions is promising for variable industrial oxygen evolution reaction (OER). Herein, we have developed a simple hydrothermal strategy to construct a three dimensional nanoflower-like VOx nanosheets (VOx/NiS/NF) that utilizes S-modified NF as substrate. NiS/NF can provide not only high-surface area for the growth of VOx but also better conductivity and stability derived from NiS. XRD shows the formation of amorphous VOx supported on NiS/NF. XPS confirms the existence and valence state of V, Ni and S. EDX and SEM elemental mapping reveal the composition and great distribution of V, O, Ni and S. SEM and TEM show that the thin VOx nanosheets covered on the surface of NiS/NF uniformly, which implying more exposed active sites. OER measurements display that VOx/NiS/NF has the outstanding catalytic activity with the lower overpotential (330 mV, 50 mA cm−2), smaller tafel slope (121 mV dec−1) and lower value of semicircle of EIS than VOx/NF. The modification of NF may be the key for enhancement performances for OER due to reduced charge transfer resistance. The strong durability of VOx/NiS/NF may be attributed to the tighter integration between VOx and NiS/NF in alkaline electrolytes. The impressive results may provide a new strategy to design suitable substrate with good dispersion and conductivity to prepare effective electrocatalysts for OER.