Rational design of marigold-shaped composite Ni3V2O8 flowers: a promising catalyst for the oxygen evolution reaction

Advancement of double spinel-type blended metal oxides and designing heterostructured nanomaterials with assorted shapes using two different metals remains an active area of research. In this work, we designed marigold flower-shaped Ni3V2O8 structures by simple and facile thermal decay of Ni(II) 8-hydroxyquinoline and VO(II) 8-hydroxyquinoline molecular precursors using a universal and green solvent, water. The marigold flower-shaped structure of Ni3V2O8 was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Finally, we tested these marigold flower-shaped Ni3V2O8 structures for their electrochemical performance, such as the oxygen evolution reaction (OER). The results demonstrated that the marigold flower-shaped Ni3V2O8 structure has superior catalytic activity (overpotential of 328 mV at 10 mA cm−2 and a Tafel slope of 61 mV dec−1) compared with a physical mixture of V2O5 and NiO (overpotential of 496 mV at 10 mA cm−2 and a Tafel slope of 158 mV dec−1), pure NiO (overpotential of 553 mV at 10 mA cm−2 and a Tafel slope of 205 mV dec−1) or V2O5 (overpotential of 668 mV at 10 mA cm−2 and a Tafel slope of 314 mV dec−1) in alkaline medium. This higher OER activity of the marigold flower-shaped Ni3V2O8 structure strengthens its adoption as a potential candidate in the field of energy storage and conversion systems.