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1. Challenging thermodynamics: combining immiscible elements in a single-phase nano-ceramic

   https://doi.org/10.1038/s41467-024-45413-w  

   Liu, Shuo ; Dun, Chaochao ; Jiang, Qike ; Xuan, Zhengxi ; Yang, Feipeng ; Guo, Jinghua ; Urban, Jeffrey J. ; Swihart, Mark T. ( February 2024 , Nature Communications)

   The Hume-Rothery rules governing solid-state miscibility limit the compositional space for new inorganic material discovery. Here, we report a non-equilibrium, one-step, and scalable flame synthesis method to overcome thermodynamic limits and incorporate immiscible elements into single phase ceramic nanoshells. Starting from prototype examples including (NiMg)O, (NiAl)O_x, and (NiZr)O_x, we then extend this method to a broad range of Ni-containing ceramic solid solutions, and finally to general binary combinations of elements. Furthermore, we report an “encapsulated exsolution” phenomenon observed upon reducing the metastable porous (Ni_0.07Al_0.93)O_xto create ultra-stable Ni nanoparticles embedded within the walls of porous Al₂O₃nanoshells. This nanoconfined structure demonstrated high sintering resistance during 640 h of catalysis of CO₂reforming of methane, maintaining constant 96% CH₄and CO₂conversion at 800 °C and dramatically outperforming conventional catalysts. Our findings could greatly expand opportunities to develop novel inorganic energy, structural, and functional materials.

    

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2. Volatile Abundances, Extended Coma Sources, and Nucleus Ice Associations in Comet C/2014 Q2 (Lovejoy)

   https://doi.org/10.3847/PSJ/ac323c  

   Dello Russo, Neil ; Vervack, Ronald J. ; Kawakita, Hideyo ; Bonev, Boncho P. ; DiSanti, Michael A. ; Gibb, Erika L. ; McKay, Adam J. ; Cochran, Anita L. ; Weaver, Harold A. ; Biver, Nicolas ; et al ( January 2022 , The Planetary Science Journal)

   Abstract High-resolution infrared spectra of comet C/2014 Q2 Lovejoy were acquired with NIRSPEC at the W. M. Keck Observatory on two post-perihelion dates (UT 2015 February 2 and 3). H 2 O was measured simultaneously with CO, CH 3 OH, H 2 CO, CH 4 , C 2 H 6 , C 2 H 4 , C 2 H 2 , HCN, and NH 3 on both dates, and rotational temperatures, production rates, relative abundances, H 2 O ortho-to-para ratios, and spatial distributions in the coma were determined. The first detection of C 2 H 4 in a comet from ground-based observations is reported. Abundances relative to H 2 O for all species were found to be in the typical range compared with values for other comets in the overall population to date. There is evidence of variability in rotational temperatures and production rates on timescales that are small compared with the rotational period of the comet. Spatial distributions of volatiles in the coma suggest complex outgassing behavior. CH 3 OH, HCN, C 2 H 6 , and CH 4 spatial distributions in the coma are consistent with direct release from associated ices in the nucleus and are peaked in a more sunward direction compared with co-measured dust. H 2 O spatial profiles are clearly distinct from these other four species, likely due to a sizable coma contribution from icy grain sublimation. Spatial distributions for C 2 H 2 , H 2 CO, and NH 3 suggest substantial contributions from extended coma sources, providing further evidence for distinct origins and associations for these species in comets. CO shows a different spatial distribution compared with other volatiles, consistent with jet activity from discrete nucleus ice sources. 

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3. Identifying UiO‐67 Metal‐Organic Framework Defects and Binding Sites through Ammonia Adsorption

   https://doi.org/10.1002/cssc.202102217  

   Swaroopa Datta Devulapalli, Venkata ; McDonnell, Ryan P. ; Ruffley, Jonathan P. ; Shukla, Priyanka B. ; Luo, Tian‐Yi ; De Souza, Mattheus L. ; Das, Prasenjit ; Rosi, Nathaniel L. ; Karl Johnson, J. ; Borguet, Eric ( December 2021 , ChemSusChem)

   Ammonia is a widely used toxic industrial chemical that can cause severe respiratory ailments. Therefore, understanding and developing materials for its efficient capture and controlled release is necessary. One such class of materials is 3D porous metal‐organic frameworks (MOFs) with exceptional surface areas and robust structures, ideal for gas storage/transport applications. Herein, interactions between ammonia and UiO‐67‐X (X: H, NH₂, CH₃) zirconium MOFs were studied under cryogenic, ultrahigh vacuum (UHV) conditions using temperature‐programmed desorption mass spectrometry (TPD‐MS) and in‐situ temperature‐programmed infrared (TP‐IR) spectroscopy. Ammonia was observed to interact with μ₃−OH groups present on the secondary building unit of UiO‐67‐X MOFs via hydrogen bonding. TP‐IR studies revealed that under cryogenic UHV conditions, UiO‐67‐X MOFs are stable towards ammonia sorption. Interestingly, an increase in the intensity of the C−H stretching mode of the MOF linkers was detected upon ammonia exposure, attributed to NH−π interactions with linkers. These same binding interactions were observed in grand canonical Monte Carlo simulations. Based on TPD‐MS, binding strength of ammonia to three MOFs was determined to be approximately 60 kJ mol⁻¹, suggesting physisorption of ammonia to UiO‐67‐X. In addition, missing linker defect sites, consisting of H₂O coordinated to Zr⁴⁺sites, were detected through the formation ofnNH₃⋅H₂O clusters, characterized through in‐situ IR spectroscopy. Structures consistent with these assignments were identified through density functional theory calculations. Tracking these bands through adsorption on thermally activated MOFs gave insight into the dehydroxylation process of UiO‐67 MOFs. This highlights an advantage of using NH₃for the structural analysis of MOFs and developing an understanding of interactions between ammonia and UiO‐67‐X zirconium MOFs, while also providing directions for the development of stable materials for efficient toxic gas sorption.

    

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4. Solid organic-coated ammonium sulfate particles at high relative humidity in the summertime Arctic atmosphere

   https://doi.org/10.1073/pnas.2104496119  

   Kirpes, Rachel M. ; Lei, Ziying ; Fraund, Matthew ; Gunsch, Matthew J. ; May, Nathaniel W. ; Barrett, Tate E. ; Moffett, Claire E. ; Schauer, Andrew J. ; Alexander, Becky ; Upchurch, Lucia M. ; et al ( April 2022 , Proceedings of the National Academy of Sciences)

   The ability of atmospheric aerosols to impact climate through water uptake and cloud formation is fundamentally determined by the size, composition, and phase (liquid, semisolid, or solid) of individual particles. Particle phase is dependent on atmospheric conditions (relative humidity and temperature) and chemical composition and, importantly, solid particles can inhibit the uptake of water and other trace gases, even under humid conditions. Particles composed primarily of ammonium sulfate are presumed to be liquid at the relative humidities (67 to 98%) and temperatures (−2 to 4 °C) of the summertime Arctic. Under these atmospheric conditions, we report the observation of solid organic-coated ammonium sulfate particles representing 30% of particles, by number, in a key size range (<0.2 µm) for cloud activation within marine air masses from the Arctic Ocean at Utqiaġvik, AK. The composition and size of the observed particles are consistent with recent Arctic modeling and observational results showing new particle formation and growth from dimethylsulfide oxidation to form sulfuric acid, reaction with ammonia, and condensation of marine biogenic sulfate and highly oxygenated organic molecules. Aqueous sulfate particles typically undergo efflorescence and solidify at relative humidities of less than 34%. Therefore, the observed solid phase is hypothesized to occur from contact efflorescence during collision of a newly formed Aitken mode sulfate particle with an organic-coated ammonium sulfate particle. With declining sea ice in the warming Arctic, this particle source is expected to increase with increasing open water and marine biogenic emissions. 

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5. Crystal structures of sodium-, lithium-, and ammonium 4,5-dihydroxybenzene-1,3-disulfonate (tiron) hydrates

   https://doi.org/10.1107/S2056989018008009  

   Herbst-Gervasoni, Corey J. ; Gau, Michael R. ; Zdilla, Michael J. ; Valentine, Ann M. ( July 2018 , Acta Crystallographica Section E Crystallographic Communications)

   The solid-state structures of the Na + , Li + , and NH 4 + salts of the 4,5-dihydroxybenzene-1,3-disulfonate (tiron) dianion are reported, namely disodium 4,5-dihydroxybenzene-1,3-disulfonate, 2Na + ·C 6 H 4 O 8 S 2 2− , μ-4,5-dihydroxybenzene-1,3-disulfonato-bis[aqualithium(I)] hemihydrate, [Li 2 (C 6 H 4 O 8 S 2 )(H 2 O) 2 ]·0.5H 2 O, and diammonium 4,5-dihydroxybenzene-1,3-disulfonate monohydrate, 2NH 4 + ·C 6 H 4 O 8 S 2 2− ·H 2 O. Intermolecular interactions vary with the size of the cation, and the asymmetric unit cell, and the macromolecular features are also affected. The sodium in Na 2 (tiron) is coordinated in a distorted octahedral environment through the sulfonate oxygen and hydroxyl oxygen donors on tiron, as well as an interstitial water molecule. Lithium, with its smaller ionic radius, is coordinated in a distorted tetrahedral environment by sulfonic and phenolic O atoms, as well as water in Li 2 (tiron). The surrounding tiron anions coordinating to sodium or lithium in Na 2 (tiron) and Li 2 (tiron), respectively, result in a three-dimensional network held together by the coordinate bonds to the alkali metal cations. The formation of such a three-dimensional network for tiron salts is relatively rare and has not been observed with monovalent cations. Finally, (NH 4 ) 2 (tiron) exhibits extensive hydrogen-bonding arrays between NH 4 + and the surrounding tiron anions and interstitial water molecules. This series of structures may be valuable for understanding charge transfer in a putative solid-state fuel cell utilizing tiron. 

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