Polyoxometalate-derived KV3O8/Ni2V2O7 composite for hydrogen evolution reaction in neutral medium

In the face of a drastic increase in environmental pollution and consequential depletion of fossil fuel reserves in the present day, greater attention has been drawn towards sustainable growth and the development of clean energy. Hydrogen, a renewable energy resource, is considered a key reservoir for sustainable energy. Hence, there is a need for an electrocatalyst that generates hydrogen via electrocatalytic water-splitting reactions. Hence, unlocking the full potential of polyoxometalates helps in the production of hydrogen via electrocatalysis. Our main focus in this article is to develop a highly efficient heterogeneous electrocatalyst for the hydrogen evolution reaction (HER). In this study, we annealed an already reported polyoxometalate (POM), K 2 [Ni(H 2 O) 6 ] 2 [V 10 O 28 ]·4H 2 O ( Ni-V-POM ), at 400 °C under an ambient atmosphere to obtain a composite material containing the KV 3 O 8 and Ni 2 V 2 O 7 phases (denoted as compound 1 ). Compound 1 has been characterized by infrared spectroscopy, powder X-ray diffraction, field emission scanning electron microscopy-energy-dispersive X-ray spectroscopy, inductively coupled plasma (ICP), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Electrocatalytic measurements of compound 1 demonstrate HER activity with a low overpotential of approximately 84.7 mV at 10 mA cm −2 , a Tafel slope of 243.3 mV dec −1 , and good stability of 12 h at a current density of 10 mA cm −2 in a neutral 0.1 M KPi buffer at pH 7.2. The synergistic effect between the KV 3 O 8 and Ni 2 V 2 O 7 improves the electrocatalyst’s performance, especially in a neutral medium. This work contributes to highly efficient heterogeneous HER electrocatalysts for neutral water electrocatalysis.