Influence of FeVO4 crystallinity on oxygen evolution reaction activity

Enhanced oxygen evolution reaction (OER) kinetics plays an important role in the large-scale production of hydrogen via water electrolysis. In this regard, the crystallinity of FeVO4 is tuned from amorphous to semicrystalline and fully crystalline via precipitation followed by controlled thermal treatment. The prepared FeVO4 samples show a uniform distribution of spherical nanoparticles (40–60 nm). The tailored amorphous, semicrystalline, and fully crystalline FeVO4 samples are immobilized on nickel foam and their OER performance was studied. The OER performance of amorphous, semicrystalline, and fully crystalline FeVO4 shows in the order of amorphous FeVO4 > semicrystalline FeVO4 > fully crystalline FeVO4. The amorphous FeVO4 demonstrates magnificent enhanced OER kinetics with a small overpotential and high current density compared to the semicrystalline and fully crystalline FeVO4. The amorphous FeVO4 exhibits an overpotential of 310 mV at a high current density of 1000 mA cm−2 and also exhibits exemplary stability over 95 h, while semicrystalline FeVO4 and fully crystalline FeVO4 respectively require 360 mV and 390 mV to drive a relatively lower current density of 500 mA cm−2.