title: Urea-Assisted Room Temperature Stabilized Metastable β-NiMoO4: Experimental and Theoretical Insights into its Unique Bifunctional Activity toward Oxygen Evolution and Supercapacitor.
abstract: Room-temperature stabilization of metastable β-NiMoO4is achieved through urea-assisted hydrothermal synthesis technique. Structural and morphological studies provided significant insights for the metastable phase. Furthermore, detailed electrochemical 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-1(at a current density of 5 A g-1) 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-NiMoO4better 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-2is 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.
authors.affiliation: School of Basic Sciences, Indian Institute of Technology , Bhubaneswar, Odisha, India -751013.
authors.forename: Satyajit
authors.initials: S
authors.lastname: Ratha
authors.affiliation: CSIR-Institute of Minerals and Materials Technology , Bhubaneswar, Odisha, India -751013.|Academy of Scientific & Innovative Research , New Delhi, India -110001.
authors.forename: Aneeya K
authors.initials: AK
authors.lastname: Samantara
authors.affiliation: School of Basic Sciences, Indian Institute of Technology , Bhubaneswar, Odisha, India -751013.
authors.forename: Krishna Kanta
authors.initials: KK
authors.lastname: Singha
authors.affiliation: High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre , Trombay, Mumbai-400085, India.
authors.forename: Abhijeet Sadashiv
authors.initials: AS
authors.lastname: Gangan
authors.affiliation: High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre , Trombay, Mumbai-400085, India.
authors.forename: Brahmananda
authors.initials: B
authors.lastname: Chakraborty
authors.affiliation: CSIR-Institute of Minerals and Materials Technology , Bhubaneswar, Odisha, India -751013.|Academy of Scientific & Innovative Research , New Delhi, India -110001.
authors.forename: Bikash Kumar
authors.initials: BK
authors.lastname: Jena
authors.affiliation: School of Basic Sciences, Indian Institute of Technology , Bhubaneswar, Odisha, India -751013.
authors.forename: Chandra Sekhar
authors.identifier: http://orcid.org/0000-0003-4380-5549
authors.initials: CS
authors.lastname: Rout
keywords: computational study; nickel molybdate; oxygen evolution; supercapacitor; urea