Structure, morphology and electrochemical properties of zinc–cobalt oxide films on AISI 304 type steel

Šulčiūtė, Agnė; Baltrušaitis, Jonas; Valatka, Eugenijus

doi:10.1007/s10800-015-0802-7

Cited by 10 publications

(9 citation statements)

References 38 publications

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“…The binding energies of the Zn 2p 3/2 and 2p 1/2 peaks are 1022.4 and 1045.5 eV, respectively, with a spin−orbital splitting of 22.9 eV, in agreement with previously reported values. 6,43,44 The Zn 2p core level steadily shifts to lower binding energy with increasing Co doping, where the maximum shift of 0.85 eV occurs for 15% Co. However, it shifts back 0.2 eV to higher binding energy for 20% Co.…”

Section: Resultsmentioning

confidence: 98%

“…The core level shift is consistent with the formation of metallic-like Zn bonds. 6,45 However, the increase in the fwhm suggests either of two things: the ZnO lattice becomes more disordered with increasing Co concentration, where disorder is due to defects in the form of interstitials, substitution, oxygen vacancy defects, and so on, 7,29 or the coexistence of zinc oxide and cobalt oxide regions within the ZnO NRs. If we assume the latter, the lower binding energy of the Zn 2p with Co doping is due to a higher content of Zn cations with fractionally more negative charge, where the formation of cobalt oxides scavenges oxygen from the zinc oxide.…”

Section: Resultsmentioning

confidence: 99%

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Evolution of the Stoichiometry and Electronic Structure of Cobalt Oxide in Thermally Treated Co-Doped ZnO Nanorods for Solar Cells

Echeverría

Kaphle²,

Austin

et al. 2019

ACS Appl. Nano Mater.

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The effects of annealing on the stoichiometry and electronic structure of Codoped ZnO nanorods (NRs), as prepared by chemical bath deposition (CBD), were investigated by photoemission spectroscopies (XPS and UPS) and X-ray diffraction (XRD). The Co 2p core level state of the as-grown Co-doped ZnO NRs is consistent with a Co 3 O 4 stoichiometry, independent of the Co concentration. Upon annealing of the as-grown material above 865 K, a Co 2p core level satellite state forms, which is consistent with the formation of CoO. The valence band density of states also exhibits changes with annealing, where a new density of states forms between the Fermi level and 1 eV below. The new valence band states are also consistent with the formation of CoO. This change in the cobalt oxide stoichiometry from Co 3 O 4 to CoO results in Zn − due to reduced O coordination, consistent with the Auger analysis. In addition, the evolution of Co 3 O 4 to CoO is irreversible upon exposure to air. The oxidation state of Co is a key parameter in the material's performance when used for solar cells.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Evolution of the Stoichiometry and Electronic Structure of Cobalt Oxide in Thermally Treated Co-Doped ZnO Nanorods for Solar Cells

Echeverría

Kaphle²,

Austin

et al. 2019

ACS Appl. Nano Mater.

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“…Modes at 660, 590, and 555 cm −1 could be assigned to vibrations of Co–O bonds in Co 3 O 4 . A peak at 660 cm −1 is often associated with vibrations of Co 2+ ions in tetrahedral coordination, while modes in 550–590 cm −1 range rise from Co 3+ vibrations in octahedral coordination [ 41 , 42 ].…”

Section: Resultsmentioning

confidence: 99%

Synthesis of ZnO Nanoparticles Doped with Cobalt Using Bimetallic ZIFs as Sacrificial Agents

et al. 2020

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We report here a simple two-stage synthesis of zinc–cobalt oxide nanoparticles. We used Zn/Co-zeolite imidazolate framework (ZIF)-8 materials as precursors for annealing and optional impregnation with a silicon source for the formation of a protective layer on the surface of oxide nanoparticles. Using bimetallic ZIFs allowed us to trace the phase transition of the obtained oxide nanoparticles from wurtzite ZnO to spinel Co3O4 structures. Using (X-ray diffraction) XRD and (X-ray Absorption Near Edge Structure) XANES techniques, we confirmed the incorporation of cobalt ions into the ZnO structure up to 5 mol.% of Co. Simple annealing of Zn/Co-ZIF-8 materials in the air led to the formation of oxide nanoparticles of about 20–30 nm, while additional treatment of ZIFs with silicon source resulted in nanoparticles of about 5–10 nm covered with protective silica layer. We revealed the incorporation of oxygen vacancies in the obtained ZnO nanoparticles using FTIR analysis. All obtained samples were comprehensively characterized, including analysis with a synchrotron radiation source.

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“…Then, the methanol formation rate from CO 2 (38 ppm h −1 g −1 cat ) was greatly improved by introducing Cu 2+ to the porphyrin-based MOF structure (260 ppm h −1 g −1 cat ) [40]. Its worthy to note that cobalt oxide and hydroxide are considered as a one of the most promising electroactive materials for high-performance electrochemical capacitors [41]. On the other hand, cobalt-based compounds and composites have been widely used as electrocatalysts, secondary batteries and also pseudocapacitors [42].…”

Section: Introductionmentioning

confidence: 99%

High selective photocatalytic CO2 conversion into liquid solar fuel over a cobalt porphyrin-based metal–organic framework

Sadeghi

2021

Photochem Photobiol Sci

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In the present study, porphyrin-based metal-organic framework (Co/PMOF) was synthesized and characterized by different spectra analyses. The photoluminescence properties of porphyrin and Co/PMOF revealed that the photoluminescence of Co/PMOF was quenched compared to the porphyrin, indicating that the lifetime of photo-generated charge carriers in Co/ PMOF is longer than porphyrin. The prepared Co/PMOF was applied as an efficient photocatalyst for CO 2 photoconversion to formate in the presence of triethanolamine (TEOA) as a sacrificial agent under visible-light irradiation. The photoreaction results showed that 23.21 µmol HCOO − was produced over Co/PMOF during the 6 h photocatalytic reaction under visible illumination, showing much better activity than the porphyrin, 4.56 µmol HCOO − . No other products were detected, suggesting that this reaction over Co/PMOF has high selectivity. Co/PMOF reusability and stability were examined through recycling tests and there were no remarkable losses of photoactivity even after three cycles of photoreaction. Moreover, FTIR measurement and UV-Vis spectra demonstrated no notable changes in Co/PMOF structure. As a result, superior photocatalytic behavior of Co/PMOF was implied for CO 2 photoreduction which highlights the great potential of assembly porphyrin and cobalt into MOFs for CO 2 photoreduction.

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Structure, morphology and electrochemical properties of zinc–cobalt oxide films on AISI 304 type steel

Cited by 10 publications

References 38 publications

Evolution of the Stoichiometry and Electronic Structure of Cobalt Oxide in Thermally Treated Co-Doped ZnO Nanorods for Solar Cells

Evolution of the Stoichiometry and Electronic Structure of Cobalt Oxide in Thermally Treated Co-Doped ZnO Nanorods for Solar Cells

Synthesis of ZnO Nanoparticles Doped with Cobalt Using Bimetallic ZIFs as Sacrificial Agents

High selective photocatalytic CO2 conversion into liquid solar fuel over a cobalt porphyrin-based metal–organic framework

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