Dynamic Molecular Investigation of the Solid-Electrolyte Interphase of an Anode-Free Lithium Metal Battery Using In Situ Liquid SIMS and Cryo-TEM.

We use in situ liquid secondary ion mass spectroscopy, cryogenic transmission electron microscopy, and density functional theory calculation to delineate the molecular process in the formation of the solid-electrolyte interphase (SEI) layer under the dynamic operating conditions. We discover that the onset potential for SEI layer formation and the thickness of the SEI show dependence on the solvation shell structure. On a Cu film anode, the SEI is noticed to start to form at around 2.0 V (nominal cell voltage) with a final thickness of about 40-50 nm in the 1.0 M LiPF6/EC-DMC electrolyte, while for the case of 1.0 M LiFSI/DME, the SEI starts to form at around 1.5 V with a final thickness of about 20 nm. Our observations clearly indicate the inner and outer SEI layer formation and dissipation upon charging and discharging, implying a continued evolution of electrolyte structure with extended cycling.

Molecular identification of wines using in situ liquid SIMS and PCA analysis.

Composition analysis in wine is gaining increasing attention because it can provide information about the wine quality, source, and nutrition. In this work, in situ liquid secondary ion mass spectrometry (SIMS) was applied to 14 representative wines, including six wines manufactured by a manufacturer in Washington State, United States, four Cabernet Sauvignon wines, and four Chardonnay wines from other different manufacturers and locations. In situ liquid SIMS has the unique advantage of simultaneously examining both organic and inorganic compositions from liquid samples. Principal component analysis (PCA) of SIMS spectra showed that red and white wines can be clearly differentiated according to their aromatic and oxygen-contained organic species. Furthermore, the identities of different wines, especially the same variety of wines, can be enforced with a combination of both organic and inorganic species. Meanwhile, in situ liquid SIMS is sample-friendly, so liquid samples can be directly analyzed without any prior sample dilution or separation. Taken together, we demonstrate the great potential of in situ liquid SIMS in applications related to the molecular investigation of various liquid samples in food science.

Hydrothermal synthesis of caterpillar-like one-dimensional NiCO3 nanosheet arrays and primary lithium battery application.

Transition metal carbonates have shown great potential as anode materials for next-generation lithium-ion batteries (LIBs), due to their super-high capacity. However, pure-phase NiCO3 with high electrochemical activity has not been reported to date. Herein, highly uniform caterpillar-like one-dimensional (1D) NiCO3 nanosheet arrays have been successfully synthesized using a facile hydrothermal route and have been evaluated as an anode material for LIBs. Profiting from the unique 1D hierarchical structure and spaces between the neighboring nanosheets, the as-prepared NiCO3 requires lower activation energy and delivers quick lithium-ion diffusion kinetics. These attributes result in a high capacity of 893 mA h g-1 after 150 cycles and excellent rate performance, superior to those of most reported transition metal carbonates. Cyclic voltammetry, ex situ X-ray diffraction and X-ray photoelectron spectroscopy reveal the lithium storage mechanism.

Highly uniform Ni(HCO3)2 spheres: the morphology evolution and electrochemical performance.

Nickel bicarbonate Ni(HCO3)2 has recently been demonstrated to be a highly attractive electrode material for lithium-ion batteries (LIBs) and supercapacitors (SCs), and its electrochemical performance could be further enhanced through rationally tuning the morphology. Herein, Ni(HCO3)2 spheres are successfully prepared via a facile, one-step hydrothermal route. The effects of the hydrothermal duration on the phase and morphology are investigated. XRD patterns indicate a phase conversion from NiCO3 into Ni(HCO3)2 that has never been previously reported. SEM images reveal that the reaction temperature and time play a key role in determining the phase and morphology of the resulting sample. The whole process includes, successively, nucleation, growth, self-assembly, dissolution, and recrystallization. As electrodes, the Ni(HCO3)2 spheres reacted for 15 h, delivering 602.4 mA h g-1 after 300 cycles at 0.2 A g-1 in LIBs and a specific capacitance of 450 F g-1 after 5000 cycles at 5 A g-1 in SCs. These results show strong potential applications in energy storage devices.

Molecular Examination of Ion-Pair Competition in Alkaline Aluminate Solutions Using In Situ Liquid SIMS.

Understanding the structure and composition of aluminate complexes in extremely alkaline systems such as Bayer liquors has received enormous attention due to their fundamental and industrial importance. However, obtaining direct molecular information of the underlying ion-ion interactions using traditional approaches such as NMR spectroscopy or Raman spectroscopy is challenging due to the weakness of these interactions and/or their complex overlapping spectral signatures. Here, we exploit in situ liquid secondary-ion mass spectrometry (SIMS) as a new approach and show how it enables new insights. In contrast with traditional techniques, using SIMS we succeeded in acquiring information on dominant ion clusters in these alkaline systems. In Na+/K+ mixed alkaline aluminate solutions, we clearly observe preferential formation of Na+-anion clusters over K+-anion clusters. Evaluation of these clusters by density functional theory (DFT) calculations shows that these structures are stable and that their relative bond energies are consistent with their observed SIMS signal intensity differences. This demonstrates a key advantage of in situ liquid SIMS for overcoming ambiguities obscuring important information in these systems on constituent molecular clusters defined by relatively weak ion-pair competition and ion-solvent interactions.

Three-Dimensional Mass Spectrometric Imaging of Biological Structures Using a Vacuum-Compatible Microfluidic Device.

Three-dimensional (3D) molecular imaging of biological structures is important for a wide range of research. In recent decades, secondary-ion mass spectrometry (SIMS) has been recognized as a powerful technique for both two-dimensional and 3D molecular imaging. Sample fixations (e.g., chemical fixation and cryogenic fixation methods) are necessary to adapt biological samples to the vacuum condition in the SIMS chamber, which has been demonstrated to be nontrivial and less controllable, thus limiting the wider application of SIMS on 3D molecular analysis of biological samples. Our group recently developed in situ liquid SIMS that offers great opportunities for the molecular study of various liquids and liquid interfaces. In this work, we demonstrate that a further development of the vacuum-compatible microfluidic device used in in situ liquid SIMS provides a convenient freeze-fixation of biological samples and leads to more controllable and convenient 3D molecular imaging. The special design of this new vacuum-compatible liquid chamber allows an easy determination of sputter rates of ice, which is critical for calibrating the depth scale of frozen biological samples. Sputter yield of a 20 keV Ar1800+ ion on ice has been determined as 1500 (±8%) water molecules per Ar1800+ ion, consistent with our results from molecular dynamics simulations. Moreover, using the information of ice sputter yield, we successfully conduct 3D molecular imaging of frozen homogenized milk and observe network structures of interesting organic and inorganic species. Taken together, our results will significantly benefit various research fields relying on 3D molecular imaging of biological structures.

A new pyrazoline-based fluorescent sensor for Al3+ in aqueous solution.

A new pyrazoline-based fluorescent sensor was synthesized and the structure was confirmed by single crystal X-ray diffraction. The sensor responds to Al(3+) with high selectivity among a series of cations in aqueous methanol. This sensor forms a 1:1 complex with Al(3+) and displays fluorescent quenching.

Two novel hierarchical homogeneous nanoarchitectures of TiO2 nanorods branched and P25-coated TiO2 nanotube arrays and their photocurrent performances.

We report here for the first time the synthesis of two novel hierarchical homogeneous nanoarchitectures of TiO2 nanorods branched TiO2 nanotube arrays (BTs) and P25-coated TiO2 nanotube arrays (PCTs) using two-step method including electrochemical anodization and hydrothermal modification process. Then the photocurrent densities versus applied potentials of BTs, PCTs, and pure TiO2 nanotube arrays (TNTAs) were investigated as well. Interestingly, at -0.11 V and under the same illumination condition, the photocurrent densities of BTs and PCTs show more than 1.5 and 1 times higher than that of pure TNTAs, respectively, which can be mainly attributed to significant improvement of the light-absorbing and charge-harvesting efficiency resulting from both larger and rougher surface areas of BTs and PCTs. Furthermore, these dramatic improvements suggest that BTs and PCTs will achieve better photoelectric conversion efficiency and become the promising candidates for applications in DSSCs, sensors, and photocatalysis.

A two-dimensional network in the molecular salt 2-methylimidazolium hydrogen glutarate, and three-dimensional networks in the salts 2-methylimidazolium hydrogen succinate and 2-methylimidazolium hydrogen adipate monohydrate.

All three title compounds, C(4)H(7)N(2)(+).C(4)H(5)O(4)(-), (I), C(4)H(7)N(2)(+).C(5)H(7)O(4)(-), (II), and C(4)H(7)N(2)(+).C(6)H(9)O(4)(-).H(2)O, (III), can be regarded as 1:1 organic salts. The dicarboxylic acids join through short acid bridges into infinite chains. Compound (I) crystallizes in the noncentrosymmetric Cmc2(1) space group and the asymmetric unit consists of a hydrogen succinate anion located on a mirror plane and a 2-methylimidazolium cation disordered across the same mirror. The other two compounds crystallize in the triclinic P1 space group. The carboxylic acid H atom in (II) is disordered over both ends of the anion and sits on inversion centres between adjacent anions, forming symmetric short O...H...O bridges. Two independent anions in (III) sit across inversion centres, again with the carboxylic acid H atom disordered in short O...H...O bridges. The molecules in all three compounds are linked into two-dimensional networks by combinations of imidazolium-carboxylate N(+)-H...O and carboxylate-carboxylate O-H...O hydrogen bonds. The two-dimensional networks are further linked into three-dimensional networks by C-H...O hydrogen bonds in (I) and by O(water)-H...O hydrogen bonds in (III). According to the DeltapK(a) rule, such 1:1 types of organic salts can be expected unambiguously. However, a 2:1 type of organic salt may be more easily obtained in (II) and (III) than in (I).

4-(5-Bromo-2-hydroxy-benzyl-idene-amino)-3-methyl-1H-1,2,4-triazole-5(4H)-thione.

In the title compound, C(10)H(9)BrN(4)OS, the triazole ring forms a dihedral angle of 72.05 (14)° with the benzene ring. The conformation of the mol-ecule is stabilized by intra-molecular O-H⋯·N hydrogen bonding. The crystal packing is determined by inter-molecular N-H⋯S inter-actions, a short Br⋯S contact of 3.4464 (13) Šand π-π stacking of the triazole rings and of the benzene rings (centroid-centroid distances of 3.4109 and 3.569 Å, respectively).

N,N-Bis(3-nitro-benzyl-idene)pyridine-2,6-dicarbohydrazide dimethyl-formamide disolvate trihydrate.

In the title compound, C(21)H(15)N(7)O(6)·2C(3)H(7)NO·3H(2)O, the N(2),N(2')-bis-(3-nitro-benzyl-idene)pyridine-2,6-dicarbohydrazide and one water mol-ecule are located on a twofold rotation axis. The mol-ecules are connected by hydrogen bonds. One dimethylformamide molecule is disordered over two positions; the site occupancy factors are ca 0.8 and 0.2.

N,N-Bis[2-(ethoxy-carbonyl-meth-oxy)-benzyl-idene]pyridine-2,6-dicarbohydrazide.

In the title compound, C(29)H(29)N(5)O(8), the ester group is disordered over two sites with site-occupancy factors of 0.91/0.09. The crystal structure is stabilized by inter- and intra-molecular hydrogen-bond inter-actions.