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1. Resolving the Chemical Formula of Nesquehonite via NMR Crystallography, DFT Computation, and Complementary Neutron Diffraction

   https://doi.org/10.1002/chem.202203052  

   Cui, Jinlei ; Prisk, Timothy R. ; Olmsted, David L. ; Su, Vicky ; Asta, Mark ; Hayes, Sophia E. ( December 2022 , Chemistry – A European Journal)

   Nesquehonite is a magnesium carbonate mineral relevant to carbon sequestration envisioned for carbon capture and storage of CO₂. Its chemical formula remains controversial today, assigned as either a hydrated magnesium carbonate [MgCO₃ ⋅ 3H₂O], or a hydroxy‐ hydrated‐ magnesium bicarbonate [Mg(HCO₃)OH ⋅ 2H₂O]. The resolution of this controversy is central to understanding this material‘s thermodynamic, phase, and chemical behavior. In an NMR crystallography study, using rotational‐echo double‐resonance¹³C{¹H} (REDOR),¹³C−¹H distances are determined with precision, and the combination of¹³C static NMR lineshapes and density functional theory (DFT) calculations are used to model different H atomic coordinates. [MgCO₃ ⋅ 3H₂O] is found to be accurate, and evidence from neutron powder diffraction bolsters these assignments. Refined H positions can help understand how H‐bonding stabilizes this structure against dehydration to MgCO₃. More broadly, these results illustrate the power of NMR crystallography as a technique for resolving questions where X‐ray diffraction is inconclusive.

    

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2. Molecular-level origin of the carboxylate head group response to divalent metal ion complexation at the air–water interface

   https://doi.org/10.1073/pnas.1818600116  

   Denton, Joanna K. ; Kelleher, Patrick J. ; Johnson, Mark A. ; Baer, Marcel D. ; Kathmann, Shawn M. ; Mundy, Christopher J. ; Wellen Rudd, Bethany A. ; Allen, Heather C. ; Choi, Tae Hoon ; Jordan, Kenneth D. ( July 2019 , Proceedings of the National Academy of Sciences)

   We exploit gas-phase cluster ion techniques to provide insight into the local interactions underlying divalent metal ion-driven changes in the spectra of carboxylic acids at the air–water interface. This information clarifies the experimental findings that the CO stretching bands of long-chain acids appear at very similar energies when the head group is deprotonated by high subphase pH or exposed to relatively high concentrations of Ca 2+ metal ions. To this end, we report the evolution of the vibrational spectra of size-selected [Ca 2+ ·RCO 2 − ] + ·(H 2 O) n =0 to 12 and RCO 2 − ·(H 2 O) n =0 to 14 cluster ions toward the features observed at the air–water interface. Surprisingly, not only does stepwise hydration of the RCO 2 − anion and the [Ca 2+ ·RCO 2 − ] + contact ion pair yield solvatochromic responses in opposite directions, but in both cases, the responses of the 2 (symmetric and asymmetric stretching) CO bands to hydration are opposite to each other. The result is that both CO bands evolve toward their interfacial asymptotes from opposite directions. Simulations of the [Ca 2+ ·RCO 2 − ] + ·(H 2 O) n clusters indicate that the metal ion remains directly bound to the head group in a contact ion pair motif as the asymmetric CO stretch converges at the interfacial value by n = 12. This establishes that direct metal complexation or deprotonation can account for the interfacial behavior. We discuss these effects in the context of a model that invokes the water network-dependent local electric field along the C–C bond that connects the head group to the hydrocarbon tail as the key microscopic parameter that is correlated with the observed trends. 

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3. Phase Relations of a Depleted Peridotite Fluxed by a CO 2 ‐H 2 O Fluid—Implications for the Stability of Partial Melts Versus Volatile‐Bearing Mineral Phases in the Cratonic Mantle

   https://doi.org/10.1029/2019JB017653  

   Saha, Sriparna ; Dasgupta, Rajdeep ( October 2019 , Journal of Geophysical Research: Solid Earth)

   We present phase‐equilibria experiments of a K‐bearing, depleted peridotite (Mg# 92) fluxed with a mixed CO₂‐H₂O fluid (0.5 wt.% CO₂and 0.94 wt.% H₂O in the bulk) to gain insight into the stability of volatile‐bearing partial melts versus volatile‐bearing mineral phases in a depleted peridotite system. Experiments were performed at 850–1150 °C and 2–4 GPa using a piston‐cylinder and a multianvil apparatus. Olivine, orthopyroxene, clinopyroxene, and spinel/garnet are present at all experimental conditions. Textural confirmation of partial melt is made at temperatures as low as 1000 °C at 2 GPa, 950 °C at 3 GPa, and 1000 °C at 4 GPa marking the onset of melting at 900–1000 °C at 2 GPa, 850–950 °C at 3 GPa, and 950–1000 °C at 3 GPa. Phlogopite and magnesite breakdown at 900–1000 °C at 2 GPa, 950–1000 °C at 3 GPa, and 1000–1050 °C at 4 GPa. Comparison with previously published experiments in depleted peridotite system with identical CO₂‐H₂O content introduced via a silicic melt show that introduction of CO₂‐H₂O as fluid lowers the temperature of phlogopite breakdown by 150–200 °C at 2–4 GPa and stabilizes partial melts at lower temperatures. Our study thus, shows that the volatile‐bearing phase present in the cratonic mantle is controlled by bulk composition and is affected by the process of volatile addition during craton formation in a subduction zone. In addition, volatile introduction via melt versus aqueous fluid, leads to different proportion of anhydrous phases such as olivine and orthopyroxene. Considering the agent of metasomatism is thus critical to evaluate how the bulk composition of depleted peridotite is modified, leading to potential stability of volatile‐bearing phases as the cause of anomalously low shear wave velocity in mantle domains such as mid lithospheric discontinuities beneath continents.

    

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4. (Digital Presentation) Ultrathin Stabilized Zn Metal Anode for Highly Reversible Aqueous Zn-Ion Batteries

   https://doi.org/10.1149/MA2022-024439mtgabs  

   Zhang, Yuxuan ; Song, Han Wook ; Lee, Sunghwan ( October 2022 , ECS Meeting Abstracts)

   Ever-increasing demands for energy, particularly being environmentally friendly have promoted the transition from fossil fuels to renewable energy.¹Lithium-ion batteries (LIBs), arguably the most well-studied energy storage system, have dominated the energy market since their advent in the 1990s.²However, challenging issues regarding safety, supply of lithium, and high price of lithium resources limit the further advancement of LIBs for large-scale energy storage applications.³Therefore, attention is being concentrated on an alternative electrochemical energy storage device that features high safety, low cost, and long cycle life. Rechargeable aqueous zinc-ion batteries (ZIBs) is considered one of the most promising alternative energy storage systems due to the high theoretical energy and power densities where the multiple electrons (Zn²⁺) . In addition, aqueous ZIBs are safer due to non-flammable electrolyte (e.g., typically aqueous solution) and can be manufactured since they can be assembled in ambient air conditions.⁴As an essential component in aqueous Zn-based batteries, the Zn metal anode generally suffers from the growth of dendrites, which would affect battery performance in several ways. Second, the led by the loose structure of Zn dendrite may reduce the coulombic efficiency and shorten the battery lifespan.⁵

   Several approaches were suggested to improve the electrochemical stability of ZIBs, such as implementing an interfacial buffer layer that separates the active Zn from the bulk electrolyte.⁶However, the and thick thickness of the conventional Zn metal foils remain a critical challenge in this field, which may diminish the energy density of the battery drastically. According to a theretical calculation, the thickness of a Zn metal anode with an areal capacity of 1 mAh cm^-2is about 1.7 μm. However, existing extrusion-based fabrication technologies are not capable of downscaling the thickness Zn metal foils below 20 μm.

   Herein, we demonstrate a thickness controllable coating approach to fabricate an ultrathin Zn metal anode as well as a thin dielectric oxide separator. First, a 1.7 μm Zn layer was uniformly thermally evaporated onto a Cu foil. Then, Al₂O₃, the separator was deposited through sputtering on the Zn layer to a thickness of 10 nm. The inert and high hardness Al₂O₃layer is expected to lower the polarization and restrain the growth of Zn dendrites. Atomic force microscopy was employed to evaluate the roughness of the surface of the deposited Zn and Al₂O₃/Zn anode structures. Long-term cycling stability was gauged under the symmetrical cells at 0.5 mA cm^-2for 1 mAh cm^-2. Then the fabricated Zn anode was paired with MnO₂as a full cell for further electrochemical performance testing. To investigate the evolution of the interface between the Zn anode and the electrolyte, a home-developed in-situ optical observation battery cage was employed to record and compare the process of Zn deposition on the anodes of the Al₂O₃/Zn (demonstrated in this study) and the procured thick Zn anode. The surface morphology of the two Zn anodes after circulation was characterized and compared through scanning electron microscopy. The tunable ultrathin Zn metal anode with enhanced anode stability provides a pathway for future high-energy-density Zn-ion batteries.

   Obama, B., The irreversible momentum of clean energy.Science2017,355(6321), 126-129.

   Goodenough, J. B.; Park, K. S., The Li-ion rechargeable battery: a perspective.J Am Chem Soc2013,135(4), 1167-76.

   Li, C.; Xie, X.; Liang, S.; Zhou, J., Issues and Future Perspective on Zinc Metal Anode for Rechargeable Aqueous Zinc‐ion Batteries.Energy & Environmental Materials2020,3(2), 146-159.

   Jia, H.; Wang, Z.; Tawiah, B.; Wang, Y.; Chan, C.-Y.; Fei, B.; Pan, F., Recent advances in zinc anodes for high-performance aqueous Zn-ion batteries.Nano Energy2020,70.

   Yang, J.; Yin, B.; Sun, Y.; Pan, H.; Sun, W.; Jia, B.; Zhang, S.; Ma, T., Zinc Anode for Mild Aqueous Zinc-Ion Batteries: Challenges, Strategies, and Perspectives.Nanomicro Lett2022,14(1), 42.

   Yang, Q.; Li, Q.; Liu, Z.; Wang, D.; Guo, Y.; Li, X.; Tang, Y.; Li, H.; Dong, B.; Zhi, C., Dendrites in Zn-Based Batteries.Adv Mater2020,32(48), e2001854.

   Acknowledgment

   This work was partially supported by the U.S. National Science Foundation (NSF) Award No. ECCS-1931088. S.L. and H.W.S. acknowledge the support from the Improvement of Measurement Standards and Technology for Mechanical Metrology (Grant No. 22011044) by KRISS.

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5. Low concentrations of Cu 2+ in synthetic nutrient containing wastewater inhibit MgCO 3 -to-struvite transformation

   https://doi.org/10.1039/D0EW01035A  

   Barčauskaitė, Karolina ; Drapanauskaitė, Donata ; Silva, Manoj ; Murzin, Vadim ; Doyeni, Modupe ; Urbonavicius, Marius ; Williams, Clinton F. ; Supronienė, Skaidrė ; Baltrusaitis, Jonas ( March 2021 , Environmental Science: Water Research & Technology)

   null (Ed.)

   Simultaneous major nutrient nitrogen (N) and phosphorus (P) recovery from wastewater is key to achieving food–energy–water sustainable development. In this work, we elucidate the reaction kinetics, crystalline structure and chemical composition of the resulting solid precipitate obtained from simulated N and P containing wastewater solution using widely abundant low solubility magnesite (MgCO 3 ) particles in the presence of common transition metal ions, such as zinc (Zn 2+ ) or copper (Cu 2+ ). We show that up to 100 ppm Zn 2+ from the simulated wastewater can be incorporated into the struvite lattice as isolated distorted Zn 2+ while even at very low concentrations of ∼5 ppm Cu 2+ ions almost completely inhibit struvite crystal formation. The resulting solid precipitate distinctly affects soil microbial biomass carbon and soil dehydrogenase enzyme activity. These results show a cautionary case where abundant natural mineral MgCO 3 exhibits very different chemistry in Cu 2+ containing simulated wastewater and does not readily adsorb or retain NH 4 + and PO 4 3− ions, unlike less sustainable but more water-soluble magnesium sources, such as MgCl 2 , at the equivalent [Mg 2+ ] : [NH 4 + ] : [PO 4 3− ] molar ratio of 1.4 : 1 : 1. 

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