Document Type

Article

Publication Date

4-17-2024

Abstract

Room-temperature stabilization of metastable β-NiMoO4 is achieved through urea-assisted hydrothermal synthesis technique. Structural and morphological studies provided significant insights for the metastable phase. Furthermore, detailed electro- chemical investigations showcased its activity toward energy storage and conversion, yielding intriguing results. Comparison with the stable polymorph, α- NiMoO4, has also been borne out to support the enhanced electrochemical activities of the as-obtained β-NiMoO4. A specific capacitance of ~4188 F/g (at a current density of 5 A/g) has been observed showing its exceptional faradic capacitance. We qualitatively and extensively demonstrate through the analysis of density of states (DOS) obtained from first-principles calculations that, enhanced DOS near top of the valence band and empty 4d orbital of Mo near Fermi level make β-NiMoO4, better energy storage and conversion material compared to α- NiMoO4. Likewise, from the oxygen evolution reaction experiment, it is found that the state of art current density of 10 mA cm-2 is achieved at overpotential of 300 mV, which is much lower than that of IrO₂/C. First-principles calculations also confirm a lower overpotential of 350 mV for β-NiMoO4.

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