The relationship between crystal structures and thermochromism in CoMoO4

Costa, Rosiane Keila Santos; Teles, Stéfani Caroline; Siqueira, Kisla Prislen Félix

doi:10.1007/s11696-020-01294-z

Cited by 18 publications

(8 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, as one pronounced peak (10.35° 2θ, λ = 0.63988 Å) prior to ignition of the reaction could not be assigned to a metal oxide phase (see Section S4.3), the absolute phase composition detected via XRD for FSP-U only represents a trend. Still, the ex situ Raman spectra of the initial catalyst states (Figure a) indicated a higher amount of β-CoMoO 4 in FSP-U by the more pronounced shoulder at ∼949 cm –1 . , In contrast, a higher amount of crystalline α-CoMoO 4 was detected by synchrotron XRD in FSP-Co (∼30 wt %), compared to FSP-Fe (∼10 wt %) and FSP-U (∼13 wt %). Moreover, crystalline Fe 3 O 4 was only detected in FSP-Co and FSP-Fe.…”

Section: Results and Discussionmentioning

confidence: 90%

Role of Iron and Cobalt in 4-Component Bi–Mo–Co–Fe–O Catalysts for Selective Isobutene Oxidation Using Complementary Operando Techniques

Klag,

Gaur,

Stehle

et al. 2023

ACS Catal.

View full text Add to dashboard Cite

Structure−activity correlations in the selective oxidation of lower olefins over Bi−Mo-based mixed metal oxides are challenging but essential for a knowledge-based catalyst design and improvement of process efficiency. One important aspect is the extension of the 2-component Bi−Mo oxides to more complex mixed metal oxide (MMO) systems like Bi−Mo−Co−Fe oxides, as their higher activity and selectivity are traced back to synergistic metal oxide phase interactions. Hence, three Bi−Mo−Co−Fe oxide catalysts differing in elemental composition, especially iron and cobalt content, were tested during the selective oxidation of isobutene. The catalyst structure was studied using operando Raman spectroscopy, (synchrotron) X-ray diffraction, and X-ray absorption spectroscopy. The formation of ternary phases β-Co 0.7 Fe 0.3 MoO 4 and Bi 3 FeMo 2 O 12 resulted in an increased selectivity to methacrolein, but the overall performance strongly depended on the variety of metal oxide phases, thus pointing to the role of phase cooperation. The highest selectivity was observed with the simultaneous presence of α-Bi 2 Mo 3 O 12 , while the interplay of γ-Bi 2 MoO 6 and Fe 3 O 4 led to highly active but less selective catalysts. In this context, the reducibility of Fe 3+ to Fe 2+ was found to be crucial for moderate and controllable catalytic activity. Co 3 O 4 performed unselective by mainly favoring total oxidation product formation. Comparison with previous findings in selective propylene oxidation showed similar structural changes during the catalytic reaction, hence emphasizing similar behavior of Bi−Mo−Co−Fe oxides in lower olefin oxidation. The systematic investigation of 4-component catalysts by advanced characterization techniques is a powerful approach to gain new insights into the roles of individual catalyst phases by considering their complex phase interplay and thus receiving more profound understanding of their working principles during the selective oxidation of olefins.

show abstract

Section: Results and Discussionmentioning

confidence: 90%

Role of Iron and Cobalt in 4-Component Bi–Mo–Co–Fe–O Catalysts for Selective Isobutene Oxidation Using Complementary Operando Techniques

Klag,

Gaur,

Stehle

et al. 2023

ACS Catal.

View full text Add to dashboard Cite

show abstract

Section: Chemical Characterizationmentioning

confidence: 99%

“…Figure 1c depicts the crystal structure design of β-CoMoO4, which crystallizes in the space group C2/m (No.12). In this scheme, CoO6 octahedrons are in purple and the tetrahedrons MoO4 are in a gray color [34]. An FE-SEM equipped with EDS, TEM, and HR-TEM was employed to study the surface morphology, analyze the elemental composition, and identify the interplanar spacing of as-prepared materials.…”

Section: Chemical Characterizationmentioning

confidence: 99%

Tuning Electrochemical Hydrogen-Evolution Activity of CoMoO4 through Zn Incorporation

et al. 2023

View full text Add to dashboard Cite

Designing cheap, efficient, and durable electrocatalysts on three-dimensional (3D) substrates such as nickel foam (NF) for the hydrogen-evolution reaction (HER) is in high demand for the practical application of electrochemical water splitting. In this work, we adopted a simple one-step hydrothermal method to realize the incorporation of Zn into the lattice of CoMoO4 with various atomic concentrations—Co1-xZnxMoO4 (x = 0, 0.1, 0.3, 0.5, and 0.7). The morphological studies demonstrated that parent CoMoO4 consists of nanoflowers and nanorods. However, as the concentration of Zn increases within the host CoMoO4, the portion of nanoflowers decreases and simultaneously the portion of nanorods increases. Moreover, the substitution of Zn2+ in place of Co2+/Co3+ creates oxygen vacancies in the host structure, especially in the case of Co0.5Zn0.5MoO4, giving rise to lower charge-transfer resistance and a higher electrochemically active surface area. Therefore, among the prepared samples, Co0.5Zn0.5MoO4 on NF showed an improved HER performance, reaching 10 mA cm−2 at an overpotential as low as 204 mV in a 1.0 M KOH medium. Finally, the Co0.5Zn0.5MoO4 electrode exhibited robust long-term stability at an applied current density of 10 mA cm−2 for 20 h. The Faradaic efficiency determined by a gas chromatograph found that the hydrogen-production efficiency varied from 94% to 84%.

show abstract

“…Moreover, it has been demonstrated that replacing molybdenum with tungsten or copper with other divalent metals makes it possible to change the thermochromic response [5,8,9,10,11,12,13]. Thermochromic properties have recently also been found in other molybdates such as NiMoO 4 [14] and CoMoO 4 [15]. At ambient pressure, pure CuMoO 4 exists in two triclinic (space group P 1) phases: high-temperature green α-CuMoO 4 and low-temperature brownish γ-CuMoO 4 [16].…”

Section: Introductionmentioning

confidence: 99%

The influence of Zn2+ ions on the local structure and thermochromic properties of Cu1-xZnxMoO4 solid solutions

Pudza

Anspoks²,

Cintiņš³

et al. 2021

Materials Today Communications

View full text Add to dashboard Cite

The relationship between crystal structures and thermochromism in CoMoO4

Cited by 18 publications

References 45 publications

Role of Iron and Cobalt in 4-Component Bi–Mo–Co–Fe–O Catalysts for Selective Isobutene Oxidation Using Complementary Operando Techniques

Role of Iron and Cobalt in 4-Component Bi–Mo–Co–Fe–O Catalysts for Selective Isobutene Oxidation Using Complementary Operando Techniques

Tuning Electrochemical Hydrogen-Evolution Activity of CoMoO4 through Zn Incorporation

The influence of Zn2+ ions on the local structure and thermochromic properties of Cu1-xZnxMoO4 solid solutions

Contact Info

Product

Resources

About