Hydrate Networks under Mechanical Stress – A Case Study for Co3(PO4)2·8H2O

Bach, Sven; Visnow, Eduard; Panthöfer, Martin; Gorelik, Tatiana E.; Buzanich, Ana Guilherme; Gurlo, Aleksander; Kolb, Ute; Emmerling, Franziska; Lind, Cora; Tremel, Wolfgang

doi:10.1002/ejic.201501481

Cited by 20 publications

(11 citation statements)

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“…Ball milling leads to pronounced changes in the 31 P environments. The 13 C environment was probed as a function of the carbonate content and the alkaline earth metal using 13 The second broad resonance appears at ~162 ppm. Such chemical shifts have been reported by Nebel et al 70 for sodium and potassium hydrogen carbonate.…”

Section: Carbonate Environment: 13 C Nmr Spectroscopymentioning

confidence: 99%

“…FTIR spectroscopy provides complementary information to solid state NMR spectroscopy on the chemical transformations of MCO3/CaHPO4 (M = Ca, Sr, Ba) during ball-milling. 13 C enriched samples of aMCP (M = Ca, Sr, Ba) were used to facilitate the assignment of the carbonate or phosphate bands in the FTIR spectra. The higher mass of the 13 C isotope shifts the carbonate bands to lower wavenumbers.…”

Section: Chemical Transformations During Ball-milling: Ftir Spectroscopymentioning

confidence: 99%

“…9 Elemental germanium 10 or zeolites 11,12 show a loss of crystallinity during ballmilling, and changes of extended hydrate networks have been reported for Co3(PO4)2 × 8 H2O. 13 Ball milling can induce an alloying of metals 14 or polymorph changes (e.g., a transformation from the anatase to the rutile phase of TiO2). 15 Similarly, organic compounds mixtures of organic and inorganic compounds 16 undergo structural changes during mechanochemical treatment.…”

Section: Introductionmentioning

confidence: 99%

“…(a) SPE13 C NMR spectra and (b)13 C CP NMR spectra of aMCP (M = Ca, Sr, Ba) (xCarbonate = 0.2, tcp= 2ms) and (c)13 C CP NMR spectra ((xCarbonate = 0.5, tcp= 2ms) (all spectra: 480 min of ball milling).…”

mentioning

confidence: 99%

“…Difference spectra of aCCP (a) with xCarbonate = 0.2 and (b) with xCarbonate = 0.5 enriched with13 C and with C in natural abundance for aCCP. The spectra show the essential bands at ~1640 and 850 cm -1 assigned to (or influenced by) the carbonate vibrations.…”

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confidence: 99%

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Monitoring a Mechanochemical Reaction Reveals the Formation of a New ACC Defect Variant Containing the HCO₃^– Anion Encapsulated by an Amorphous Matrix

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Fernández-Martı́nez

et al. 2020

Crystal Growth & Design

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Amorphous calcium carbonate (ACC) is an important precursor in the biomineralization of crystalline CaCO3. In nature it serves as a storage material or as permanent structural element, whose lifetime is regulated by an organic matrix. The relevance of ACC in materials science is primarily related to our understanding of CaCO3 crystallization pathways and CaCO3/(bio)polymer nanocomposites. ACC can be synthesized by liquid-liquid phase separation, and it is typically stabilized with macromolecules. We have prepared ACC by milling calcite in a planetary ball mill. Phosphate "impurities" were added in the form of monetite (CaHPO4) to substitute the carbonate anions, thereby stabilizing ACC by substitutional disorder. The phosphate anions do not simply replace the carbonate anions. They undergo shear-driven acid/base and condensation reactions, where stoichiometric (50%) phosphate contents are required for the amorphization to be complete. The phosphate anions generate a strained network that hinders ACC recrystallization kinetically. The amorphization reaction and the structure of BM-ACC were studied by quantitative Fourier transform infrared spectroscopy and solid state 31 P, 13 C, and 1 H magic angle spinning nuclear magnetic resonance spectroscopy, which are highly sensitive to symmetry changes of the local environment. In the first-and fast-reaction step, the CO3 2

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Section: Carbonate Environment: 13 C Nmr Spectroscopymentioning

confidence: 99%

Section: Chemical Transformations During Ball-milling: Ftir Spectroscopymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Monitoring a Mechanochemical Reaction Reveals the Formation of a New ACC Defect Variant Containing the HCO₃^– Anion Encapsulated by an Amorphous Matrix

Opitz

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Fernández-Martı́nez

et al. 2020

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Autologous Cobalt Phosphates with Modulated Coordination Sites for Electrocatalytic Water Oxidation

Lin

Chen

et al. 2020

Angewandte Chemie

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The correlation between metal coordination and electrocatalytic water oxidation performance is elusive in many cobalt‐based materials. Herein, we designed an ideal Co phosphate‐based platform to explore the effect of coordination environment on oxygen evolution reaction (OER) activity. The cobalt geometry was modulated from octahedral to tetrahedral by simple removal of water ligands in Co3(PO4)2⋅8 H2O. Other features except the coordination structure in the two autologous materials remain similar. The two analogues display the same OER kinetics, but the anhydrous Co3(PO4)2 exhibits a greatly enhanced OER activity. On the basis of Raman and operando XAS results, the higher intrinsic activity of the Co tetrahedral sites is because they facilitate the formation of active high valent cobalt (hydr)oxide intermediates during OER. This work not only brings insights of OER on Co‐based electrocatalysts but also provides a reference system to study the effect of metal geometry on electrocatalysis.

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Autologous Cobalt Phosphates with Modulated Coordination Sites for Electrocatalytic Water Oxidation

et al. 2020

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The correlation between metal coordination and electrocatalytic water oxidation performance is elusive in many cobalt-based materials. Herein, we designed an ideal Co phosphate-based platform to explore the effect of coordination environment on oxygen evolution reaction (OER) activity. The cobalt geometry was modulated from octahedral to tetrahedral by simple removal of water ligands in Co 3 (PO 4 ) 2 ·8 H 2 O. Other features except the coordination structure in the two autologous materials remain similar. The two analogues display the same OER kinetics, but the anhydrous Co 3 (PO 4 ) 2 exhibits a greatly enhanced OER activity. On the basis of Raman and operando XAS results, the higher intrinsic activity of the Co tetrahedral sites is because they facilitate the formation of active high valent cobalt (hydr)oxide intermediates during OER. This work not only brings insights of OER on Co-based electrocatalysts but also provides a reference system to study the effect of metal geometry on electrocatalysis.Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.Figure 3. a) CVs, b) Tafel plots based on kinetic currents, c) DPV curves of the Co 3 (PO 4 ) 2 ·8 H 2 O and Co 3 (PO 4 ) 2 . The electrochemical response of d) Co 3 (PO 4 ) 2 and e) Co 3 (PO 4 ) 2 ·8 H 2 O in electrolytes with different pH values. f) The linear plots of the pre-catalytic oxidation potentials and the kinetic catalytic currents against the pH values of the electrolytes (colours as in a-c).

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Hydrate Networks under Mechanical Stress – A Case Study for Co₃(PO₄)₂·8H₂O

Cited by 20 publications

References 66 publications

Monitoring a Mechanochemical Reaction Reveals the Formation of a New ACC Defect Variant Containing the HCO₃^– Anion Encapsulated by an Amorphous Matrix

Monitoring a Mechanochemical Reaction Reveals the Formation of a New ACC Defect Variant Containing the HCO₃^– Anion Encapsulated by an Amorphous Matrix

Autologous Cobalt Phosphates with Modulated Coordination Sites for Electrocatalytic Water Oxidation

Autologous Cobalt Phosphates with Modulated Coordination Sites for Electrocatalytic Water Oxidation

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Hydrate Networks under Mechanical Stress – A Case Study for Co3(PO4)2·8H2O

Cited by 20 publications

References 66 publications

Monitoring a Mechanochemical Reaction Reveals the Formation of a New ACC Defect Variant Containing the HCO3– Anion Encapsulated by an Amorphous Matrix

Monitoring a Mechanochemical Reaction Reveals the Formation of a New ACC Defect Variant Containing the HCO3– Anion Encapsulated by an Amorphous Matrix

Autologous Cobalt Phosphates with Modulated Coordination Sites for Electrocatalytic Water Oxidation

Autologous Cobalt Phosphates with Modulated Coordination Sites for Electrocatalytic Water Oxidation

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Product

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Hydrate Networks under Mechanical Stress – A Case Study for Co₃(PO₄)₂·8H₂O

Monitoring a Mechanochemical Reaction Reveals the Formation of a New ACC Defect Variant Containing the HCO₃^– Anion Encapsulated by an Amorphous Matrix

Monitoring a Mechanochemical Reaction Reveals the Formation of a New ACC Defect Variant Containing the HCO₃^– Anion Encapsulated by an Amorphous Matrix