Raman spectroscopy of nickel molybdate and its modifications

Popovych, Orest; Budzulyak, І. М.; Yukhymchuk, V.О.; Budzulyak, S. I.; Popovych, D. I.

doi:10.1080/1536383x.2021.1925253

Cited by 22 publications

(24 citation statements)

References 25 publications

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“…, but the refinement of the crystal structure parameters is difficult. In the Raman spectra of NiMoO4 hydrate [9] we did not find any vibrational modes responsible for nitrates, nickel hydroxide or molybdenum oxide, which indicates the formation of single-phase nickel molybdate hydrate in hydrothermal synthesis. The synthesis resulted in NiMoO4 hydrate with a triclinic crystal structure corresponding to the P1 ̅ space group.…”

Section: Resultsmentioning

confidence: 66%

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Ultrasonic modification of nanocrystalline NiMoO4 hydrate obtained by hydrothermal method

Popovych

Budzulyak

Kotsyubynsky

et al. 2022

Phys. Chem. Solid St.

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The paper presents the results of studies of the crystal structure, surface morphology and electrical properties of nickel molybdate obtained by hydrothermal method and modified by ultrasound. The influence of the duration of ultrasonic dispersion on the crystallites size, specific surface area, pore size distribution and activation energy of charge carriers of nickel molybdate hydrate is determined. It was found that ultrasound with a frequency of 22 kHz and a duration of 90 min leads to an increase in the total volume of mesopores from 0.135 cm2/g to 0.223 cm2/g with an average diameter of 28.5 nm.

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Section: Resultsmentioning

confidence: 66%

“…NiMoO4 hydrate was obtained by hydrothermal method, the synthesis procedure is described in the previous article [9]. Ultrasonic modification of the material was carried out for 15, 60 and 90 min in distilled water using an ultrasonic dispersant, the operating frequency of which is 22 kHz.…”

Section: Methodsmentioning

confidence: 99%

Ultrasonic modification of nanocrystalline NiMoO4 hydrate obtained by hydrothermal method

Popovych

Budzulyak

Kotsyubynsky

et al. 2022

Phys. Chem. Solid St.

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“…The occurrence of this band in the hydrate spectrum can be justified by coordinated water bending fluctuation modes. [38][39][40] The UNMP NPs@MSs material was further examined by X-ray photoelectron spectroscopy (XPS) analysis to examine the existing surface chemistry and oxidation states of the presented elements. The total survey scan spectrum in Fig.…”

Section: Resultsmentioning

confidence: 99%

Rational construction of porous marigold flower-like nickel molybdenum phosphates via ion exchange for high-performance long-lasting hybrid supercapacitors

Kiran

Ramulu

Arbaz

et al. 2023

Inorg. Chem. Front.

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“…The major peaks at 814 and 940 cm –1 in Ni 56 Co 7 Mo 37 correlate to the stretching vibrations of Co–O–Mo in β-CoMoO 4 (Figure b), while the peak at ca. 986 and 280 cm –1 corresponds to polymolybdates and their bending modes, respectively . Another phase of specific interest in Ni 56 Co 7 Mo 37 is a small fraction of Co 3 O 4 at 680 cm –1 attributed to Co–O stretching vibrations in octahedral units (A 1g ), indicating the formation of cobalt structures at higher Mo surface concentrations .…”

Section: Resultsmentioning

confidence: 99%

Tuning the Ni/Co Ratios and Surface Concentration of Reduced Molybdenum States for Enhanced Electrocatalytic Performance in Trimetallic Molybdates: OER, HER, and MOR Activity

Maarisetty

Hang

Chou

et al. 2022

ACS Appl. Energy Mater.

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The heterogeneous nature of trimetallic catalyst systems comes with beneficial synergy for catalytic applications. Nonetheless, the challenges associated to validate and control the critical characteristics for enhanced electrocatalytic efficiencies are yet to be known. Herein, a genre of trimetallic catalysts were synthesized with Ni, Co, and Mo metals, whose morphological, structural, electronic, and interface properties depend on Ni/Co and Mo+4/Mo+5 ratios and the dominant element on the surface of the catalyst. The results suggest that introduction of a third metal, that is, Mo, is only beneficial when the Ni/Co ratio is optimally maintained. By combining the surface electronic and structural analyses such as electron energy loss spectroscopy, X-ray photoelectron spectroscopy, line scan, Raman spectra, and electrochemical data, it was realized that Mo and metallic Ni on the surface favor oxygen evolution reaction (OER), and methanol oxidation reaction (MOR) activity, respectively. Interestingly, the adsorbed water molecules were found to be vital for higher performance in both OER and MOR processes. The chronopotentiometry tests performed with the optimized catalyst Ni56Co7Mo37 for OER showed an overpotential around ca. 309 mV at ca. 720 mA·cm–2 even after 17 h (and also a Tafel slope of 60 mV·dec–1 at 10 mA·cm–2). The peak current density (from the cyclic voltammetry tests) in the optimized catalyst, that is, Ni66Co31Mo3 (for MOR), showed almost 300-fold higher activity in 1 M KOH + 1 M CH3OH solution when compared with only 1 M KOH. Further, comparative studies were also conducted with bimetallic catalysts of Ni, Co, and Mo to understand the better combinations for promoting OER, hydrogen evolution reaction, and MOR efficiencies. This work highlights the importance of maintaining the elemental composition ratios at the bulk and surface that lead to an active environment for OER and MOR processes and thereby opening gateways for a rational design of trimetallic electrocatalysts.

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Raman spectroscopy of nickel molybdate and its modifications

Cited by 22 publications

References 25 publications

Ultrasonic modification of nanocrystalline NiMoO4 hydrate obtained by hydrothermal method

Ultrasonic modification of nanocrystalline NiMoO4 hydrate obtained by hydrothermal method

Rational construction of porous marigold flower-like nickel molybdenum phosphates via ion exchange for high-performance long-lasting hybrid supercapacitors

Tuning the Ni/Co Ratios and Surface Concentration of Reduced Molybdenum States for Enhanced Electrocatalytic Performance in Trimetallic Molybdates: OER, HER, and MOR Activity

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