Characterisation of cobalt–zinc hydroxycarbonates and their products of decomposition

Baird, T.; Campbell, Kenneth C.; Holliman, Peter J.; Hoyle, Robert; Stirling, Diane; Williams, B. Peter; Morris, Michael J.

doi:10.1039/a606759j

Cited by 61 publications

(59 citation statements)

References 18 publications

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“…From the literature, it is already known that for Co2p XPS, the Co(II) and Co(III) have almost similar 2p binding energies (BE) but they can be differentiated by the Co2p 1/2 -2p 3/2 spin-orbit level energy spacing, which is 16.0 eV for high-spin Co(II) and 15.0 eV for low-spin Co(III). 58 The BEs of Co in ZnCo 2 O 4 were found to be 60,61 In addition, the Zn : Co ratio was also consistent with 1 : 2 and 2 : 1 for ZnCo 2 O 4 and (Co 3 O 4 )/(ZnO) 6 . The O1s spectrum (Fig.…”

Section: Resultsmentioning

confidence: 78%

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Uncovering the prominent role of metal ions in octahedral versus tetrahedral sites of cobalt–zinc oxide catalysts for efficient oxidation of water

et al. 2016

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The fabrication and design of earth-abundant and high-performance catalysts for the oxygen evolution reaction (OER) are very crucial for the development and commercialization of sustainable energy conversion technologies. Although spinel catalysts have been widely explored for the electrochemical oxygen evolution reaction (OER), the role of two geometrical sites that influence their activities has not been well established so far. Here, we present more effective cobalt-zinc oxide catalysts for the OER than 'classical' Co 3 O 4 . Interestingly, the significantly higher catalytic activity of ZnCo 2 O 4 than that of

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Section: Resultsmentioning

confidence: 78%

“…6) consistent with the presence of Zn(II). 60,61 The O1s spectra showed dramatic changes between $530.8 and 532.5 eV in the O2 region (Fig. S17 †).…”

Section: -74mentioning

confidence: 99%

Uncovering the prominent role of metal ions in octahedral versus tetrahedral sites of cobalt–zinc oxide catalysts for efficient oxidation of water

et al. 2016

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“…The low-crystalline features of the cobalt hydroxide carbonate species were also identified as the main background components. In a previous study 37 where ĲNH 4 ) 2 CO 3 was used as the precipitation agent, cobalt hydroxide carbonate was obtained as the only compound. The crystallization of Co 3 O 4 occurring under our experimental conditions could be ascribed to the longer ageing procedure at 80°C herein employed that could favour Co 2+ → Co 3+ oxidation.…”

Section: Resultsmentioning

confidence: 99%

Co₃O₄ particles grown over nanocrystalline CeO₂: influence of precipitation agents and calcination temperature on the catalytic activity for methane oxidation

Pantaleo

Carlo

et al. 2015

Catal. Sci. Technol.

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aCrystalline cobalt oxides were prepared by a precipitation method using three different precipitation agents, ĲNH 4 ) 2 CO 3 , Na 2 CO 3 and COĲNH 2 ) 2 . Cobalt oxide nanoparticles corresponding to a Co 3 O 4 loading of 30 wt% were also deposited over high-surface area nanocrystalline ceria by the same precipitation agents. The effect of calcination temperature, 350 or 650°C, on the morphological and structural properties was evaluated. Characterization by BET, XRD, SEM, TEM, Raman spectroscopy, H 2 -TPR, XPS and NH 3 -TPD was performed and the catalytic properties were explored in the methane oxidation reaction. The nature of the precipitation agent strongly influenced the textural properties of Co 3 O 4 and the Co 3 O 4 -CeO 2 interface. The best control of the particle size was achieved by using COĲNH 2 ) 2 that produced small and regular crystallites of Co 3 O 4 homogeneously deposited over the CeO 2 surface. Such a Co 3 O 4 -CeO 2 system precipitated by urea showed enhanced low-temperature reducibility and high surface Co 3+ concentration, which were identified as the key factors for promoting methane oxidation at low temperature. Moreover, the synergic effect of cobalt oxide and nanocrystalline ceria produced stable full conversion of methane in the entire range of investigated temperature, up to 700-800°C, at which Co 3 O 4 deactivation usually occurs.

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“…Under this atmosphere cobalt ions experiment different red-ox processes with temperature, 18) so contrary to many other spinel oxides, a low thermal stability can be expected for the cobaltite spinels. According to this, some authors have pointed out that the Zn/Co spinel composition undergoes a thermal decomposition centered at 930°C, 8) or 1000°C, 19) which should be attributed to the reduction of the trivalent cobalt to its divalent state. Using different thermal decomposition methods other authors however suggest that zinc cobaltite is only stable up to 800°C; at higher temperatures the structure looses oxygen decomposing into a mixture of ZnO and CoO.…”

Section: Introductionmentioning

confidence: 99%

Thermal evolution of ZnCo2O4 spinel phase in air

Peiteado

Caballero

Makovec

2010

J. Ceram. Soc. Japan

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ZnCo 2 O 4 ceramics with a spinel-like structure are versatile functional materials which depending on the synthesis conditions may exhibit magnetic, electric, optical and/or catalytic characteristics. However under air atmosphere, cobalt ions experiment different red-ox processes with temperature, so contrary to many other spinel oxides, a low thermal stability can be expected for this cobaltite spinels. In addition, the final outcome of these transformations will be as well defined by the solid state chemistry of the ZnOCo x O y couple, i.e. by the partial solubility of cobalt in zinc oxide and zinc in the different cobalt oxides. At first the similarity in charge and ionic size suggests the possibility of substitutional solid solution for both the Co II into the ZnO wurtzite structure and the Zn II into the CoO rock-salt structure. However it has been observed that once the spinel structure collapses, all the zinc diffuses into the rock salt phase.

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Characterisation of cobalt–zinc hydroxycarbonates and their products of decomposition

Cited by 61 publications

References 18 publications

Uncovering the prominent role of metal ions in octahedral versus tetrahedral sites of cobalt–zinc oxide catalysts for efficient oxidation of water

Uncovering the prominent role of metal ions in octahedral versus tetrahedral sites of cobalt–zinc oxide catalysts for efficient oxidation of water

Co₃O₄ particles grown over nanocrystalline CeO₂: influence of precipitation agents and calcination temperature on the catalytic activity for methane oxidation

Thermal evolution of ZnCo2O4 spinel phase in air

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Characterisation of cobalt–zinc hydroxycarbonates and their products of decomposition

Cited by 61 publications

References 18 publications

Uncovering the prominent role of metal ions in octahedral versus tetrahedral sites of cobalt–zinc oxide catalysts for efficient oxidation of water

Uncovering the prominent role of metal ions in octahedral versus tetrahedral sites of cobalt–zinc oxide catalysts for efficient oxidation of water

Co3O4 particles grown over nanocrystalline CeO2: influence of precipitation agents and calcination temperature on the catalytic activity for methane oxidation

Thermal evolution of ZnCo2O4 spinel phase in air

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Co₃O₄ particles grown over nanocrystalline CeO₂: influence of precipitation agents and calcination temperature on the catalytic activity for methane oxidation