Non-metal Cations Research Articles

Non-metal doping enhsances oxygen reduction kinetics and CO2 tolerance of SrFeO3-δ perovskite as high-performance cathodes for solid oxide fuel cells

The sluggish of the oxygen reduction reaction (ORR) kinetics and the susceptibility to CO2 interactions are major barriers to the widespread application of solid oxide fuel cells (SOFCs). In this study, a non-metal cation doping strategy was employed to enhance the ORR catalytic activity and CO2 tolerance of SrFeO3-δ cathode. SrFe1-xPxO3-δ (SFPx, x = 0, 0.05, 0.1, 0.15, 0.2) materials were synthesized by substituting phosphorus (P) for Fe in SrFeO3-δ. The doping of P facilitated the formation of oxygen vacancies in SrFeO3-δ, enhancing oxygen adsorption, dissociation, diffusion, and charge transfer processes, leading to a notable increase in ORR catalytic activity. At 800 ℃, the polarization resistance of SFP0.15 was 0.08 Ω cm2, a reduction of 42.86 % compared to undoped SrFeO3-δ. Additionally, SFP0.15 achieved a peak power density of 749.36 mW cm2, representing a 91.99 % enhancement over SrFeO3-δ. These findings suggest that non-metal cation doping is an effective approach to boost the performance of SrFeO3-δ perovskite cathode.

(Invited) Elucidating the Cation Effect in CO2 Electroreduction Using Non-Metal Cations

Electrochemical reduction of CO2 may enable a promising route for the recycling of CO2 and the sustainable production of chemicals and fuels. Due to the complex electrochemical environment, a deeper understanding of the reaction mechanism, particularly the role of cations in the process, is still needed. It was recently demonstrated that metal cations are essential for the CO2 reduction to CO, by stabilizing the CO2 – intermediate via electrostatic interaction. Here we investigate the cation effect in CO2 reduction using non-metal cations, particularly quaternary ammonium cations, whose size and shape symmetry can be tuned. We select CO2 reduction on Bi catalyst that produces both CO and formate, thus to reveal and compare the effect of cations on the two reaction pathways. Interestingly, the Faradaic efficiency for CO production increased apparently for the electrolyte with larger cations, while the formate Faradaic efficiency showed a weak dependence on the cation size, indicating a reaction-pathway-dependent effect of the cations. We further compared cations with different symmetries and observed a more profound effect of substituted ammonium cations on the CO2 reduction activity and selectivity, which was attributed to the charge distribution and weak hydration shells of the cations that help stabilize reaction intermediates. Our work elucidates the critical role of cations in the CO2 electroreduction catalysis and suggests a method to improve the electrocatalysis with optimized electrolytes.

Chromium iodate: the structure and origin of optical second harmonic generation.

Iodate crystal materials are some of the important candidates for mid-infrared nonlinear optical (NLO) crystals. Almost all the structures and NLO properties of monometallic iodates have been studied, except for a few difficult to synthesize crystalline phases. In this work, crystalline Cr(IO3)3 was synthesized and its optical properties were studied. Cr(IO3)3 has a strong powder second-harmonic generation (SHG) effect (1.3 × AgGaS2) and a large birefringence (0.24) at 2100 nm. Theoretical calculations indicate that the 3d orbital of Cr3+ is strongly involved in the SHG process, and the contribution of the metal cation centered unit CrO6 to the SHG response is much greater than that of the non-metal cation centered unit IO3. This study provides a new case among the few NLO materials in which the SHG response is dominated by metal cation centered groups.

Stable Ammonium-Ion Batteries in Diluted Electrolyte By Manipulation of H-Bonding Network Via Ethylene Glycol

Aqueous rechargeable batteries (ARB) arose considerable interest for stationary energy storage due to low cost, inherent safety, and environmental friendliness.[1] Besides aqueous lithium-ion batteries, various kinds of aqueous batteries have been proposed, utilizing relatively inexpensive charge carriers either based on metal (Na+, K+, Ca2+, Mg2+, Zn2+, Al3+, etc.) or non-metal cations (H3O+, NH4 + etc.).[2] Among non-metallic ion batteries, aqueous ammonium-ion batteries (AAIBs) distinguish themselves by working in near neutral or mild acidic environment, refraining from severe electrode corrosion.[3] However, like other ARB systems, the energy density of AAIBs is limited by the narrow electrochemical stability window of the aqueous electrolyte. In addition, NH4 + ions hydrolyse in water resulting in decreased pH of the electrolyte which promotes the hydrogen evolution reaction (HER).[3] This means that increasing salt concentration may not be an effective strategy to enlarge the stability window of the electrolyte. In fact, according to a previous report, the cathodic stability of 25 m ammonium acetate (NH4Ac) is even slightly inferior than that of 1 M NH4Ac.[4] Developing alternative strategies to inhibit HER in diluted electrolytes is of uttermost importance.In diluted aqueous electrolytes, the continuous and complicated H bond network among water molecules favours fast ionic motion but also causes severe HER. Here, we propose ethylene glycol (EG) as electrolyte component to manipulate the H bond structure in diluted (1 m) NH4Ac solutions. FTIR results are used to study the H-bonding network as function of the EG:water ratio. The diluted aqueous electrolyte containing EG show no freezing point and wider electrochemical window. As a proof-of-concept, full cells composed of Prussian blue derivatives, PTCDI anode, and 1 m NH4Ac with the addition of EG are tested to verify the effectiveness of EG during battery operation. Improved cycling performance and higher coulombic efficiencies are demonstrated compared to those including 1 m NH4Ac in water.

Challenging metal-ion rocking-chair and zinc-ion mechanisms in mild acidic to neutral aqueous electrolytes

The utilization of 2,5-ditertbutyl hydroquinone (DTBHQ) as a potential active material in aqueous zinc-ion batteries (AZIBs) was studied for the first time. Thanks to its two hydrophobic groups, DTBHQ demonstrates a maximum solubility of 629 µM/L, significantly lower than that of other reported small quinone derivatives for AZIBs. This property translates to remarkable long-term capacity retention, even at a high electrolyte to active mass ratio. Significantly, our findings provide unequivocal support for a proton insertion mechanism as the main electrochemical process in the solid state in mono- and divalent aqueous electrolytes, thereby challenging the prevailing notion of metal-ion rocking-chair and zinc-ion mechanisms widely reported for aqueous batteries. This novel insight that holds for electrolytes based on metal- (K+, Zn2+ and Mg2+) and non-metal cations (NH4+ and NH3OH+) has profound implications for the understanding and development of aqueous batteries since the operating reduction potential was found to be directly proportional to the pKa values of the predominant acid/base couple of the tested aqueous electrolytes.

Reinforced bonding of Mo-doped MnO2 with ammonium-ion as cathodes for durable aqueous MnO2–Zn batteries

Aqueous rechargeable Zn//MnO2 batteries have attracted extensive research interest owing to their low cost and high energy density. However, the slow reaction kinetics, the disproportionation of the MnO2 cathode, and the irreversible phase transition mechanism considerably restrict their development. Here, we chose Mo-doped α-MnO2 (Mo–MnO2) as the cathode material and proposed a stable N–H⋯O bond-reinforced interaction formed via NH4+ intercalation to stabilize the 2 × 2 tunnel structure of Mo–MnO2. Theoretical and experimental studies were conducted to demonstrate the performance of the cathode. Mn3+ dissolution was effectively inhibited, and lattice distortion did not occur during the proton insertion/removal process, which further improved the cyclic stability of the cathode. Specifically, at a current density of 100 mA g−1, the Mo–MnO2 cathode exhibited a specific capacity of 265.2 mA h g−1, the energy density was 364.3 W h kg−1, and the cathode exhibited excellent cyclic stability. At a current density of 2.0 A g−1, the specific capacity was 95.2% after 1000 cycles. This work provides further insight into the bond interaction between nonmetallic cations in the main materials of electrodes and contributes to the construction of aqueous-based zinc-ion batteries with high energy density and long-term cycling capability.

Cation affinity purification of histidine-tagged proteins.

Protein purification is a basic technology in both biological research and industrial production, and efficient, convenient, economical, and environmentally friendly purification methods have always been pursued. In this study, it was found that alkaline earth metal cations (Mg2+, Ca2+) and alkali metal cations (Li+, Na+, K+) and even nonmetal cations (e.g., NH4+, imidazole, guanidine, arginine, lysine) can precipitate multi-histidine-tagged proteins (at least two tags in a whole protein) at low salts concentrations that are 1-3 orders of magnitude lower than salting-out, and precipitated proteins could be dissolved at moderate concentration of corresponding cation. Based on this finding, a novel cation affinity purification method was developed, which requires only three centrifugal separations to obtain highly purified protein with purification fold similar to that of immobilized metal affinity chromatography. The study also provides a possible explanation for unexpected protein precipitation and reminds researchers to consider the influence of cations on the experimental results. The interaction between histidine-tagged proteins and cations may also have broad application prospects. KEY POINTS: • Histidine-tagged proteins can be precipitated by low-concentrations common cations • A novel nonchromatographic protein purification method was developed • Purified protein can be obtained in pellet form by only three centrifugations.

Effects of NH4+ doping on the hydrogen storage properties of metal hydrides

Doping can modify the properties of metal hydrogen storage materials significantly. Currently, the metal doping is a frequent strategy, while the non-metal cation doping has not been examined extensively so far. In this study, the effects of NH4+ doping on the hydrogen storage properties of different metal hydrides, including TiH2, Ti0·25V0·25Nb0·25Zr0·25H2, Ti0·5V0·5H2 and VH2, are investigated by first-principles calculations. It is found that the NH4+ presents a good affinity for metal hydrides and the NH4+ incorporation leads to charge redistribution and formation of dihydrogen bond. Furthermore, the NH4+ doping in metal hydrides is favorable for enhancing the hydrogen storage capacity and decreasing the thermal stability simultaneously. The possible reason for the NH4+ doping induced destabilization in metal hydrides is the relatively weak interaction between NH4+ and hydrogen atoms.

Coordination polymers of perylenetetracarboxylate with Cs(I) ions: 3D structures with 2D inorganic layers or triple coordination nets

The self-assembly of perylenetetracarboxylate (ptc) with Cs(I) ions at ambient temperature has been investigated with two coordination polymers being synthesized and structurally characterized. The diffusion of ethanol into a Cs-ptc solution led to the formation of compound 1 [(Cs4(ptc)(H2O)5·nH2O] displaying a compact three-dimensional (3D) structure constructed with 2D undulating layers of Cs polyhedra linked by ptc ligands in two types coordination modes. Extensive π···π interactions among stacking ptc ligands formed large hydrophobic organic channels between the inorganic layers. The addition of ethylenediamine (ED) to the reaction system afforded the formation of compound 2 [(H2ED)5Cs2(ptc)3(H2O)10] showing triple 2D coordination nets with protonated ethylene diammonium cations hydrogen-bonded to both non-bonded carboxyl oxygen and coordinated water molecules. The triple 2D nets are further linked via hydrogen bonding to form a 3D structure. The optical absorption, band gap analysis, vibrational modes and thermal stability of compound 1 were also investigated. Overall, the structural diversity was achieved in the studied self-assembly system at ambient temperature through varying Cs to ptc ratios by introducing ethylene diammonium as a non-metal cation.

Tailoring NH4+ storage by regulating oxygen defect in ammonium vanadate

Defect engineering is an effective strategy for modifying the energy storage materials to improve their electrochemical performance. However, the impact of oxygen defect and its content on the electrochemical performances in the burgeoning aqueous NH4+ storage field remains explored. Therefore, for the first time in this work, an oxygen-defective ammonium vanadate [(NH4)2V10O25·8H2O, denoted as Od-NHVO] with a novel 3D porous flower-like architecture was achieved via the reduction of thiourea in a mild reaction condition, which is a facile method that can realize the intention to regulate the oxygen defect content, with the capability of mass-production. The as-prepared OdM-NHVO with moderate oxygen defect content can deliver a stable specific capacitance output (505 F g−1, 252 mAh g−1 at 0.5 A g−1 with ∼80% capacitance retention after 10,000 cycles), which benefits from extra active sites, unimpeded NH4+-migration path and relatively high structure integrity. In contrast, low oxygen defect content will lead to the torpid electrochemical reaction kinetics while too high content of it will reduce the charge-storage capability and induce structural disintegration. The superior NH4+-storage behavior is achieved with the reversible intercalation/de-intercalation process of NH4+ accompanied by forming/breaking of hydrogen bond. As expected, the assembled flexible OdM-NHVO//PTCDI quasi-solid-state hybrid supercapacitor (FQSS HSC) also exhibits high areal capacitance, energy density and reliable flexibility. This work provides a new avenue for developing materials with oxygen-deficient structure for application in various aqueous non-metal cation storage systems.

Novel and emerging concepts related to cationic species in zeolites: Characterization, chemistry and catalysis

This review surveys our efforts to form and characterize cationic species located in the micropores of various zeolites, both for metal and non-metal cations, with specific emphasis on their novel, emerging properties, and reactivity. Herein, it is described how we realized synthesis of such species with a focus on both cation identity as well as zeolite architecture, and synthesis methods. Well-defined cationic species could be produced by careful choice of metal incorporation methods, Al distribution tuning and synthesis parameters. Previously unknown phenomena in zeolite and cation-zeolite chemistry were discovered by employing these well-defined systems and will be covered in this review article. Methodology to dramatically improve stability of cations in zeolite for adsorption and catalytic applications, and usefulness of these materials in elucidating hitherto unknown catalytic intermediates and mechanisms will be discussed.

Effects of different glass formers on Li2S–P2S5–MS2(M = Si, Ge, Sn) chalcogenide solid‐state electrolytes

AbstractChalcogenide solid‐state electrolytes (SSEs) have been receiving growing attentions due to their high ionic conductivity and suitable mechanic properties, especially the Li2S–P2S5systems incorporated with a second glass network formers (Si, Ge, Sn, and so on) besides P. Although the ionic conductivities are generally enhanced with the second glass network formers, the comprehensive effects of different glass formers on other properties, including electrochemical, cycling, and air stability, remain elusive. To acquire deeper understanding, herein, three common but representative glass network formers (SiS2, GeS2, and SnS2) were introduced into Li2S–P2S5, and their individual effects were investigated systematically. The results of multiscale characterizations before and after lithium stripping/plating cycling confirmed that the introduction of metal cations (Ge, Sn) generally leads to worse electrochemical stability and shorter cycle life of these SSEs toward lithium metal compared with SSEs with nonmetal cation (Si) modification. However, the air stability is related to the binding energy of M–S (M = Si, Ge, Sn), which is consistent with the hard base soft acid theory. This work provides valuable understanding for designing pragmatic Li2S–P2S5–MS2‐based SSEs with high electrochemistry, cycling, and air stability.

Recent Advances in Aqueous Batteries with Nonmetal Cations as Charge Carriers

During the past decades, aqueous rechargeable batteries have been receiving much attention on account of the merits of cost efficiency, high safety, and environmental benignity. Compared to metal‐ions (such as Li+, Na+, K+, Mg2+, Zn2+, Al3+ etc.) as charge carriers in aqueous ion batteries, nonmetal charge carriers not only form covalent–ionic bonds in framework, but also act as reversible redox centers. Moreover, nonmetal charge carriers have advantages of low costs and high volumetric energy densities. Recently, huge efforts have been contributed to performance improvements in aqueous nonmetal cation batteries via a variety of methods. Herein, the recently reported cathode, anode materials, and newly proposed electrochemical reaction mechanisms for rechargeable aqueous nonmetal cation batteries are reviewed.

Front Cover: Siloxane Coordination Revisited: Si−O Bond Character, Reactivity and Magnificent Molecular Shapes (Eur. J. Inorg. Chem. 29/2021)

The Front Cover shows some of the most beautiful “blooms” as well as “exotic birds” obtained in the course of the coordination of siloxanes to metal and non-metal cations. The accompanying review article summarizes the dynamic development of siloxane coordination chemistry in recent years and discusses the special properties of Si−O bonding. The elusive Si-O bond character on the one hand limits possible coordination, but on the other hand, it has promoted research around siloxane bonding and activation. This has led to new preparative possibilities in the synthesis of macrocyclic ligands and their complexes. Credit (cover background): pixabay. More information can be found in the Review by F. Dankert and C. von Hänisch.

Determination of the Composition of Substances Migrating from Plugs Based on Bromo-Butyl Rubber into Infusion and Injection Preparations

The results of experimental studies of the composition of individual substances migrating from medical rubber plugs produced both in and abroad based on technical bromobutyl rubber are presented. The quantitative content of volatile organic compounds related to species impurities of gasoline was determined by gas chromatography from a standard glass bottle sealed with a sterile stopper based on bromobutyl rubber. The method of atomic emission spectroscopy was used to determine (indirect) the presence of organometallic, organosulfur and metal-inorganic compounds that did not pass through chromatographic columns, and the presence of organometallic, organosulfur and metal-inorganic compounds was determined by the content of metal and non-metal cations. The results of mass spectral studies of extracts of aqueous extracts from plugs based on bromobutyl rubber showed that they contain impurities of bromo-alkanes and bromo-arenes, which are direct-acting carcinogens.

Synthesis, Crystal Structures and Characterization of Two Nonmetal Cation Tetrafluoroborates

Two new nonmetal cation tetrafluoroborate phases [H3tren](BF4)3 (I) and [H3tren](BF4)3 HF (II) were synthesized by microwave-assisted solvothermal and characterized by single crystal X-ray diffraction, IR spectroscopy and thermal analysis DTA-TGA. [H3tren](BF4)3 is cubic (P213) with unit cell parameter a = 11.688(1) Å. [H3tren](BF4)3•HF is trigonal (R3c) with unit cell parameters a = 15.297(6) Å and c = 12.007(2) Å. Both (I) and (II) structures can be described from isolated tetrafluoroborate BF4- anions, triprotonated tris-(2-aminoethyl)amine (tren) [H3tren]3+. Phase (II) contains disordered BF4- tetrahedron and hydrofluoric acid.

(Invited) Considerations of Ionic Charge Carriers for Aqueous Rechargeable Batteries

There is a pressing need for new battery technologies in two key areas: high-energy power batteries for electric vehicles, and large-scale storage batteries to buffer the output from the renewable-but-intermittent solar and wind power generation. For storage batteries, the goal is to minimize the levelized energy cost over the devices’ lifetime. This means that electrode materials containing rare and expensive elements should be avoided. Secondly, the cycle life of storage batteries must be excellent — ideally over 10,000 cycles. Thirdly, these batteries should be quickly rechargeable to store, for example, energy from wind farms. Most importantly, storage batteries should be intrinsically safe, i.e., nonflammable. To meet this list of requirements, batteries with aqueous electrolytes relish several distinct advantages. Aqueous electrolytes are cheaper and safer. The simplicity of an aqueous chemistry environment may facilitate long battery longevity, and its high conductivity brings an innate power advantage. In battery chemistry design, one of the most important considerations is the choice of working charge carriers. To date, a majority of battery technologies rely on metal-ion charge carriers. Surprisingly, non-metal cations, particularly proton-containing cations, i.e., H+, H3O+,1 and NH4 +,1,2, have received exceedingly little attention. The simplest form of hydrogen cation, a single proton, is nearly “invisible” with a measured radius of ~0.89 fm or ~2.1 fm, using muon or e- spectroscopy, respectively. Due to the negligible strain of hosting protons, the rate capability and cycle life of proton batteries have the potential to be far superior to those of existing batteries. In this talk, I will introduce some of our new results, experimental and computational, on the storage of new charge carriers in battery chemistry for grid-storage purposes, particularly related to the Grotthuss mechanism3 and the ion/electrode interactions. I will compare different charge carriers in terms of their correlations to electrochemical properties, such as capacity fading, polarization, and operation potentials.

Novel Non-Metal Cation (NMC) Pentaborate Salts of Some Amino Acids.

Non-metal cation (NMC) pentaborate structures, in which some amino acids (valine, leucine, isoleucine, and threonine) were used as cations, were synthesized. The structural characterization of molecules was carried out by elemental analysis, FT-IR, mass, 11B-NMR, and thermal analysis (TGA/DTA) methods. The hydrogen storage capacity of molecules was also calculated by taking experimental results into consideration. The FT-IR spectra support the similarity of structures. The characteristic peaks attributable to pentaborate rings and amino acids were observed. When thermal analysis data were examined, it was observed that pentaborate salts gave similar degradation steps and degradation products. As a final degradation product of all thermal analysis experiments, a glassy form of B2O3 was observed. The valine pentaborate is the most thermally stable. Also, the amounts of hydrate water outside the coordination sphere of the compounds were determined by thermal analysis curves. The peaks of boric acid, triborate, and pentaborate structures were obtained in ppm with the 11B-NMR results of synthesized pentaborate compounds. With powder X-ray spectroscopy, all structures were found to be crystalline but not suitable for single-crystal X-ray analysis. The molecular cavities of the compounds detected by BET were found to be 3.286, 1.873, 2.309, and 1.860 g/cm3, respectively. A low number of molecular cavities can be interpreted in several existing hydrogen bonds in structures. The hydrogen storage capacities of the molecules were found to be in the range of 0.04 to 0.07% by mass.

Assembly of histidine-rich protein materials controlled through divalent cations

Nanostructured protein materials show exciting biomedical applications, since both structure and function can be genetically programmed. In particular, self-assembling histidine-rich proteins benefit from functional plasticity that allows the generation of protein-only nanoparticles for cell targeted drug delivery. However, the rational development of constructs with improved functions is limited by a poor control of the oligomerization process. By exploring cross-interactions between histidine-tagged building blocks, we have identified a critical architectonic role of divalent cations. The obtained data instruct about how histidine-rich protein materials can be assembled, disassembled and reassembled within the nanoscale through the stoichiometric manipulation of divalent ions, in a biochemical approach to biomaterials design. Statement of SignificanceDivalent metal and non-metal cations such as Ni2+, Cu2+ Ca2+ and Zn2+ have been identified as unexpected molecular tools to control the assembling, disassembling and reassembling of histidine-rich protein materials at the nanoscale. Their stoichiometric manipulation allows generating defined protein-protein cross-molecular contacts between building blocks, for a powerful nano-biochemical manipulation of the material’s architecture.

NH4+ Topotactic Insertion in Berlin Green: An Exceptionally Long-Cycling Cathode in Aqueous Ammonium-Ion Batteries

Aqueous batteries represent promising solutions for large-scale energy storage considering the cost, safety, and performance. Despite the tremendous efforts devoted to the metal cations as charge carriers for batteries, scarce attention has been paid to the non-metal cations such as proton or ammonium. In this study, we report that a Berlin green framework exhibits much greater structural compatibility for NH4+ (de)insertion than Na+ and K+. Ex situ structural studies reveal that the topochemistry of NH4+ in Berlin green is of nearly zero strain. The NH4+ topotactic performance gives rise to a higher operation potential and an ultralong cycling performance of 50,000 cycles with 78% capacity retention, far superior to Na+ and K+ (de)insertion. Furthermore, we propose a double-ion battery, where the Berlin green cathode hosts NH4+ and sodium titanium phosphate NaTi2(PO4)3 accommodates Na+ during operation. Such a new system exhibits promising results in capacity and cycling life. Our results point to a new ...