Multiple Anions Research Articles

High-entropy Li-rich layered oxide cathode for Li-ion batteries

High-entropy oxides (HEOs) are emerging as promising cathode materials for Li-ion batteries (LIBs) due to their stable solid-state phase and compositional flexibility. Herein, we investigate the structural and electrochemical properties of a novel non-equimolar high-entropy cathode material, termed high-entropy Li-rich layered oxide (HE-LLO, Li1.15Na0.05Ni0.19Mn0.56Fe0.02Mg0.02Al0.02O1.97F0.03), in comparison to a pristine Li-rich layered oxide (PR-LLO, Li1.2Ni0.2Mn0.6O2). The incorporation of multiple cations (Na+, Al3+, Mg2+, Fe3+) and anion (F−) into HE-LLO introduces compositional diversity, enhancing structural stability through the entropy stabilization effect. Theoretical calculations confirm a significantly higher configurational entropy in HE-LLO compared to PR-LLO, supporting its high-entropy nature. Electrochemical evaluations demonstrate that HE-LLO exhibits considerable capacity retention, preserving 76.8 % of its discharge capacity at 0.5C after 200 cycles, compared to only 36.2 % for PR-LLO. Even under high-temperature conditions, HE-LLO outperformed PR-LLO, maintaining 76.1 % of its discharge capacity after 100 cycles at 5C, while PR-LLO retained only 12.4 %. These enhancements are attributed to the improved phase reversibility and higher Li+ ion diffusion coefficients of HE-LLO, validated by ex-situ characterizations using a synchrotron X-ray technique, along with density functional theory (DFT) calculations. These findings highlight the promise of non-equimolar HEOs as a novel design strategy for high-performance cathode materials.

High-Entropy Multiple-Anion Aqueous Electrolytes for Long-Life Zn-Metal Anodes.

Aqueous zinc-ion batteries (AZIBs) hold great promise for large-scale energy storage applications, however, their practical use is significantly hindered by issues such as zinc dendrite growth and hydrogen evolution. To address these challenges, we propose a high-entropy (HE) electrolyte design strategy that incorporates multiple zinc salts, aimed at enhancing ion kinetics and improving the electrochemical stability of the electrolyte. The interactions between multiple anions and Zn2+ increase the complexity of the solvation structure, resulting in smaller ion clusters while maintaining weakly anion-rich solvation structures. This leads to improved ion mobility and the formation of robust interphase layers on the electrode-electrolyte interface. Moreover, the HE electrolyte effectively suppresses hydrogen evolution and corrosion side reactions while facilitating uniform and reversible Zn plating/stripping processes. Impressively, the optimized electrolyte enables dendrite-free Zn plating/stripping for over 3000 h in symmetric cells and achieves a high Coulombic efficiency of 99.5% at 10 mA cm-2 in asymmetric cells. Inspiringly, full cells paired with Ca-VO2 cathodes demonstrate excellent performance, retaining 81.5% of the initial capacity over 1800 cycles at 5 A g-1. These significant findings highlight the potential of this electrolyte design strategy to improve the performance and lifespan of Zn-metal anodes in AZIBs.

Epitaxial Growth of Silver Clusters from Ag57 to Ag72 via Laminating Multiple Different Anion Templates.

The established capability of anion templates in precisely manipulating the size, geometry, and function of metal clusters is well acknowledged. However, the development of a systematic methodology for orchestrating the assembly of silver clusters, particularly those encompassing multiple distinct types of anion templates, remains elusive due to the formidable synthetic challenge. In this work, we report two novel silver clusters, Ag57 and Ag72, using two and three different anion templates, respectively. Ag57 features a gyroscope-like monovalent cation with an Ag3 triangle core sandwiched by one [SiW9O34]10- and a triad of Cl- anion templates. By intentionally introducing the third anion template, SO42-, the structure is expanded to the unprecedented Ag72 (with 15 silver atoms epitaxially grown on top of Ag57) resembling a tumbler, inside of which two Ag3 layers are laminated by one [SiW9O34]10-, seven Cl- and one SO42- anion templates in parallel with respect to longitudinal orientation. It is noteworthy that Ag72 exhibits remarkable structural complexity and represents a pioneering achievement as the first silver cluster incorporating three distinct types of anion templates. In addition, Ag72 demonstrates a significant advantage over Ag57, particular in terms of applications such as luminescent thermometers and remote laser ignition.

Epitaxial Growth of Silver Clusters from Ag57 to Ag72 via Laminating Multiple Different Anion Templates

The established capability of anion templates in precisely manipulating the size, geometry, and function of metal clusters is well acknowledged. However, the development of a systematic methodology for orchestrating the assembly of silver clusters, particularly those encompassing multiple distinct types of anion templates, remains elusive due to the formidable synthetic challenge. In this work, we report two novel silver clusters, Ag57 and Ag72, using two and three different anion templates, respectively. Ag57 features a gyroscope‐like monovalent cation with an Ag3 triangle core sandwiched by one [SiW9O34]10− and a triad of Cl− anion templates. By intentionally introducing the third anion template, SO42−, the structure is expanded to the unprecedented Ag72 (with 15 silver atoms epitaxially grown on top of Ag57) resembling a tumbler, inside of which two Ag3 layers are laminated by one [SiW9O34]10−, seven Cl− and one SO42− anion templates in parallel with respect to longitudinal orientation. It is noteworthy that Ag72 exhibits remarkable structural complexity and represents a pioneering achievement as the first silver cluster incorporating three distinct types of anion templates. In addition, Ag72 demonstrates a significant advantage over Ag57, particular in terms of applications such as luminescent thermometers and remote laser ignition.

Modeling High Concentration Bisalt-in-Sulfolane Electrolytes and the Observation of Ligand-Bridged Cation-Pair Complexes.

Despite the abundance of sodium over lithium in Earth's crust and the copious amounts of expensive lithium salt required to make Li-ion high-concentration electrolytes (HCEs), studies of HCEs made from sodium salts remain sparse. A comparative molecular-level study of Li- and Na-ion HCEs and mixed cation or bisalt HCEs in an organic solvent is missing. To fill this gap, we studied model HCEs of pure and mixed Li and Na salts of bis(fluorosulfonyl)amide (FSI) in sulfolane using a confluence of classical molecular dynamics (MD), ab initio MD (AIMD) simulations, and quantum chemical cluster calculations. While Li-ion HCEs display transport properties superior to those of Na-ion HCEs, the latter's performance can be considerably improved by replacing even 25% of Na-ions with Li-ions. While the effects of doping are largely systemic, a larger sensitivity of the identity of solvation shells of Li-ions to the Li-content of the HCE is observed; in contrast, those of Na-ions are more oblivious to it. Fascinating ligand-bridged, short-distance cation pairs observed in the classical MD simulations are confirmed using density functional theory-based AIMD simulations. Quantum chemical calculations in the gas phase reveal the thermodynamic stability of such cation pairs complexed with multiple anions and solvent molecules.

In Situ Single-phase Formation of LaCl(CN2) Mixed-Anion Compound Via Controlled Pyrolysis of La3+ Modified Melamine Precursor.

Nitride (N3-) or cyanamide (CN22-) based mixed-anion compounds stand as attractive materials due to their unique properties derived from the binary or multiple anions, although their synthesis remains challenging in incorporating the N3- or CN22- anions safely. This work highlights the first demonstration of in situ single phase formation of a LaCl(CN2) mixed-anion compound from a stable single source precursor, melamine modified with LaCl3 preparable under aqueous conditions. The in situ formation of LaCl(CN2) involves the chemical modification of melamine with LaCl3 to form a complex. Upon heating of the precursor under N2 flowing, this complex generates cyanamide species around 400 °C, which react with LaCl3 and nonsublimated melamine to afford a binary LaCl(CN2)/g-C3N4 composite. Further pyrolysis at 800 °C decomposes the g-C3N4 counterpart, resulting in the LaCl(CN2) single-phase formation. The electronic properties of the precursor-derived single phase LaCl(CN2) were studied by the density functional theory calculation and UV-vis spectroscopy combined with X-ray photoelectron spectroscopy analyses and characterized by measuring 4.7, 1.8, and -2.9 eV for the band gap energy, the valence band maximum, and the conduction band minimum relative to Fermi energy, respectively. This study paves the way for exploring various cyanamide-based mixed anion compounds, advancing their potential applications in various fields.

Decomposition of tetracycline with peroxymonosulfate activated by an ordered hierarchical pores Fe-N/C catalyst rich in FeNx sites: Insights into singlet oxygen mechanism

FeNx sites show significant superiority in the degradation of antibiotic contaminants, but there are difficulties in successfully constructing highly dispersed FeNx sites. In this work, Fe-N/C catalysts doped with hierarchical ordered pores structure and FeNx active sites were prepared by metal node exchange strategy. Among them, Fe-N/C-2 had more excite species for peroxymonosulfate (PMS) owing to the synergy between Fe and N coordination, which achieved 89.36 % tetracycline (TC) removal rate within 20 min, and its reaction kinetic (k = 0.245 min−1) is 7.66 times more than original PMS system. Moreover, the material exhibited excellent activation performance in a variety of complex water environments, such as the coexistence of multiple anions, strong acids and alkalis (pH = 2.90 ∼ 10.73), and natural organic matter interference. Chemical bond detection confirmed the successful formation of FeNx sites, free radical trapping experiments showed that FeNx was the main catalytic site, and 1O2 was the main active component. Furthermore, the reaction principle of the FeNx site catalyzing the production of 1O2 from PMS was revealed in detail through mechanism exploration. Next, the probable pathways of TC decomposition were elaborated in terms of the intermediates identified by Liquid Chromatograph Mass Spectrometer (LC-MS). This study emphasized the significant potential of synthesizing Fe-N/C catalysts with activated FeNx sites, elucidated mechanism of FeNx in PMS activation, and confirmed its feasibility in TC degradation.

Strain and Substrate-Induced Electronic Properties of Novel Mixed Anion-Based 2D ScHX2 (X = I/Br) Semiconductors.

Exploration of compounds featuring multiple anions beyond the single-oxide ion, such as oxyhalides and oxyhydrides, offers an avenue for developing materials with the prospect of novel functionality. In this paper, we present the results for a mixed anion layered material, ScHX2 (X: Br, I) based on density functional theory. The result predicted the ScHX2 (X: Br, I) monolayers to be stable and semiconducting. Notably, the electronic and mechanical properties of the ScHX2 monolayers are comparable to well-established 2D materials like graphene and MoS2, rendering them highly suitable for electronic devices. Additionally, these monolayers exhibit an ability to adjust their band gaps and band edges in response to strain and substrate engineering, thereby influencing their photocatalytic applications.

Accelerating lithium ion transport via increasing the entropy of the electrolyte for stable lithium metal batteries

Promoting inorganic-rich solid-electrolyte interphase (SEI) formation by constructing anion-rich solvated structures is a promising strategy for improving the long-term cycling of lithium-metal batteries. However, the increase of anions within the solvated structure inevitably reduces the coordination of Li+ with the solvent, which leads to a low lithium diffusion coefficient and a decreased lithium conductivity. Here, high entropy electrolyte is achieved by increasing the molecular diversity in electrolyte. Multiple anions (TFSI−, FSI−, NO3− and PF6−) presented in entropy electrolyte individually coordinate with Li+, creating a diverse and anion-rich solvation structure. The large variety of solvation structures leads to a diversified Li+ diffusion barriers in the electrolyte, which results in the increase of channels available for Li+ diffusion. Thus, three-dimensional diffusion with high Li+ diffusion coefficient occurs in HE electrolytes. Furthermore, the anion-rich solvation structures promote the formation of the inorganic-rich SEI. As a result, over 2000 h of reversible Li plating/stripping with a low overpotential less than 27 mV is achieved in Li||Li cell using electrolyte modified by high-entropy strategy. Besides, the Li||LFP full cell with a negative capacity/positive capacity (N/P) ratio of 4.52 exhibits remarkably enhanced cycling stability, retaining 83.6% of its initial capacity after 150 cycles. This strategy offers a novel approach for accelerating Li+ transport kinetics and constructing stable SEI in lithium metal batteries.

Cation-disordered Li2FeTiO4 nanoparticles with multiple cation and anion redox for symmetric lithium-ion batteries

Cation-disordered Li2FeTiO4 nanoparticles with multiple cation and anion redox for symmetric lithium-ion batteries

One-step removal of anionic/cationic heavy metal ions from wastewater by magnetic amphoteric adsorbent

Simultaneous treatment of wastewater containing anionic and cationic pollutants in an easy-to-operate and environmentally friendly manner is a formidable challenge in environmental remediation. This work designed a low-cost and high-efficient amphoteric adsorbent Fe3O4/Mg-Al LDOs/AlS (SMA) for the simultaneous removal of Cr (VI) and Cu (II) pollutants from wastewater in one step. SMA is prepared with waterworks aluminum-containing sludge (AlS) from typical municipal engineering waste as the base material and loaded with magnetic nanoparticles to enhance recycling process after adsorption. SMA exhibits large specific surface area (∼418 m2/g), thereby providing sufficient adsorption active sites. Adsorption studies indicate that the adsorption of SMA toward two pollutants conforms to the pseudo-second-order kinetic model, while the Langmuir model is used to simulate the adsorption isotherm. The maximum adsorption capacity is calculated to be 235.3 mg/g for Cr (VI) and 669.2 mg/g for Cu (II). Thermodynamic studies reveal the process's spontaneous nature. The main adsorption mechanisms involve electrostatic attraction, surface complexation, isomorphic replacement, and chemical precipitation. Notably, SMA exhibits excellent adsorption performance in a wide pH range and water system containing multiple anions and cations. Moreover, the strong magnetic property facilitates easy separation and recovery through an external magnetic field, maintaining stable adsorption performance even after five cycles. Therefore, this study provides a win-win strategy for promoting environmental safety, not only proposing feasible approaches for the high value-added utilization of waste sludge, but also efficiently addressing the purification problem of complex anionic and cationic coexisting wastewater.

Interaction of Diisopropyl methyl Phosphonate (DIMP) with magnesium oxide at elevated temperatures

Diisopropyl Methyl Phosphonate (DIMP) is a liquid widely considered a surrogate for chemical warfare agents (CWA). Respectively, its interactions with different surfaces must be understood to predict the fate of CWA in various scenarios involving their release. Magnesium oxide (MgO) is a combustion product of metallized energetic materials and can serve as a model material for other common oxides. Thus, its interaction with DIMP is of both fundamental and practical interest. In this work, powders of MgO produced by different methods and having different surface areas and crystallite sizes were exposed to liquid DIMP and heated above the DIMP boiling point in a thermal analyzer. The residue remaining on the surface of different powders was quantified and examined using infrared spectroscopy. It was found that the mass of the residue scaled with the specific surface area determined based on the MgO crystallite sizes. The results suggest that the residue consists of P-CH3 molecular groups with the phosphorus attached to multiple surface oxygen anions. The residue was found to be discontinuous on smaller crystallites, but it could form a continuous monolayer on larger crystallites. The presence of Mg(OH)2 prevented interactions between DIMP and the solid surface.

Entropy-regulated electrolytes for improving Zn2+ dynamics and Zn anodes reversibility

Entropy-regulated electrolytes exhibit improved performance exceeding traditional liquid systems. Despite their potential merits, the impacts of entropy on thermodynamics and kinetic properties of the electrolyte have remained elusive. A specially designed entropy-regulated Zn-salt electrolyte (ERE) with multiple halogen anions (Cl−, Br−, and I−) is proposed here to discuss the correlation between locally excess entropy and diffusion properties. Owing to the higher pair-correlated entropy of the ERE compared to single-anion systems, it can greatly facilitate the Zn2+ transport and impede the ion aggravation, thus elevating the stability of Zn anodes. The Zn2+ transference number of ERE reaches a high value of 0.822, contributing to much improved cycling life and Coulombic efficiency of plating/stripping processes of Zn anodes. Moreover, the high-entropy identity results in better anti-freezing ability of the electrolyte system, therefore ensuring the ERE stably operating even under a low temperature of −40 °C. This work can provide valuable directions for designing high-performance electrolytes for various batteries by modulating specific excess entropy.

A supramolecular fluorescence sensor array for the differentiation of multiple anions and prediction of iodine in artificial urine using machine learning.

The simultaneous discrimination and detection of multiple anions in an aqueous solution has been a major challenge due to their structural similarity and low charge radii. In this study, we have constructed a supramolecular fluorescence sensor array based on three host-guest complexes to distinguish five anions (F-, Cl-, Br-, I-, and ClO-) in an aqueous solution using anionic-induced fluorescence quenching combined with linear discriminant analysis. Due to the different affinities of the three host-guest complexes for each anion the anion quenching efficiency for each host-guest complex was likewise different, and the five anions were well recognized. The fluorescence sensor array not only distinguished anions at different concentrations (0.5, 10, and 50 µM) with 100% accuracy but also showed good linearity within a certain concentration range. The limit of detection (LOD) was < 0.5 µM. Our interference study showed that the developed sensor array had good anti-interference ability. The practicability of the developed sensor array was also verified by the identification and differentiation of toothpaste brands with different fluoride content and the prediction of the iodine concentration in urine combined with machine learning.

Data-driven optimization and machine learning analysis of compatible molecules for halide perovskite material

Optoelectronic stability of halide perovskite material in hostile conditions such as water is rather limited, preventing them from further industrial deployment. Here, we optimize and perform machine learning analysis on CH3NH3PbI3 materials with additives, solvents and post-treatment molecules using combined experimental and data-driven methods. A champion system consisting of a compatible tertiary molecular combination ‘calcein+PbBr2 + DMSO’ active at diverse surfaces is identified, delivering a large aqueous photoelectrochemical (PEC) photocurrent of 10-5 A/cm2 and an improved aqueous stability of 92.5%. Subsequently, machine interpretation is provided to decouple the multi-molecule contributions with the assistance of genetic programming (GP) and extra-trees (ET) machine learning models, highlighting the intricate molecular features for the target outputs. The post-hoc density functional theory (DFT) calculation suggests the presence of multiple hydrogen bond and anion··π surface interactions to stabilize the interfacial structures. The present ‘PEC + GP + ET + DFT’ approach is suggested to be an effective approach to design and comprehensively evaluate molecule-modified materials.

Pentanary Oxythiogermanates Ba3MGe3O2S8 (M = Ca, Zn) Featuring [Ge3O2S8]8- Trimers and {[MGe3O2S8]6-}∞ Chains: Structural Chemistry and Physical Properties.

Oxychalcogenides are increasingly attracting wide attention because they contain multiple anions that may combine the advantages of oxides and chalcogenides. In this work, two new pentanary oxythiogermanates, Ba3MGe3O2S8 [M = Ca (1), Zn (2)], were synthesized by a high-temperature solid-state reaction. They crystallize in the orthorhombic space group Pnma, and their structures contain isolated [Ge3O2S8]8- units constructed by one [GeO2S2] and two [GeOS3] tetrahedra that link with M2+ ions to build the {[MGe3O2S8]6-}∞ chain, representing a new type of oxythiogermanate. Notably, a [ZnS5] square pyramid exists in 2. Their structural chemistry and relationship with relevant structures are analyzed. 1 and 2 exhibit wide band gaps of 3.93 and 2.63 eV, birefringences of 0.100 and 0.089 at 2100 nm, respectively, and also obvious photocurrent responses. This work may be extended to a family of AE3MIIMIV3O2Q8 (AE = alkali-earth metal; MII = Ca, Zn, Cd, Hg; MIV = Si, Ge, Sn; Q = S, Se), and further systematic survey on them can be performed to enrich the study of multifunctional oxychalcogenides.

An Integrated Precipitation–Electrodeposition–Electrodialysis Strategy for Efficient Close-Loop Recovery of Multiple Anions from Phosphogypsum Leachate

An Integrated Precipitation–Electrodeposition–Electrodialysis Strategy for Efficient Close-Loop Recovery of Multiple Anions from Phosphogypsum Leachate

Sequence closed-loop recovery of fluoride, phosphate, and sulfate anions from phosphogypsum leachate via precipitation-electrodialysis-crystallization approaches

Phosphogypsum (PG) is a large-scale industrial by-product generated during the production of phosphoric acid, typically being deposited in landfills worldwide. The leaching of fluoride (F−), phosphate (PO43−), and sulfate (SO42−) anions from PG into water bodies through rainfall results in significant environmental pollution. Herein, we propose a stepwise precipitation combined with electrodialysis and crystallization strategy for efficient recovery and valorization of multiple anions from PG leachate. Our method demonstrates effectiveness both theoretically and practically. Consequently, fluoride anions were precipitated as CaF2 and Ca5(PO4)3F at pH 4.7, with a recovery rate of 98.80 %; phosphate anions as MgNH4PO4·H2O at pH 8.5, with a recovery rate of 99.91 %; and sulfate anions through electrodialysis and crystallization with a recovery efficiency of 99.89 %, ensuring effluent met discharge standards. In addition, the concentrated sulfate-rich solution was employed for electrochemical production of persulfate, yielding ammonium persulfate salts after cooling crystallization. Our integrated approach for multiple anion recovery from PG leachate offers significant environmental and economic benefits, providing valuable insights and references for future research and practical production.

Effective green treatment of sewage sludge from Fenton reactions: Utilizing MoS2 for sustainable resource recovery

Effectively managing sewage sludge from Fenton reactions in an eco-friendly way is vital for Fenton technology's viability in pollution treatment. This study focuses on sewage sludge across various treatment stages, including generation, concentration, dehydration, and landfill, and employs chemical composite MoS2 to facilitate green resource utilization of all types of sludge. MoS2, with exposed Mo4+ and low-coordination sulfur, enhances iron cycling and creates an acidic microenvironment on the sludge surface. The MoS2-modified iron sludge exhibits outstanding (>95%) phenol and pollutant degradation in hydrogen peroxide and peroxymonosulfate-based Fenton systems, unlike unmodified sludge. This modified sludge maintains excellent Fenton activity in various water conditions and with multiple anions, allowing extended phenol degradation for over 14 d. Notably, the generated chemical oxygen demand (COD) in sludge modification process can be efficiently eliminated through the Fenton reaction, ensuring effluent COD compliance and enabling eco-friendly sewage sludge resource utilization.

Visualizing anions by color changing response: Exploitation of pyrimidine-based probe for simultaneous detection of CN− and F− ions

An easily scalable pyrimidine-based charge-transfer probe has been synthesized that can be utilized for simultaneous detection of both CN− and F− ions. The orange-colored solution of compound turns into yellow upon addition of F− ion, while the spiking of CN- ion leads to a colorless solution. Such color-changes have also been noticed on solid-supported materials, such as modified paper strips. Interestingly, the interaction with F- is found to be rapid as well as reversible (checked against water), while for cyanide ion, the scenario is completely opposite, the interaction is rather slow (∼10 min incubation time), and irreversible. The detailed spectroscopic investigation indicated that F−, being basic in nature, participates in the hydrogen bonding interaction. However, CN− ion, due to its highly nucleophilic character, formed Michael addition reaction product. Both these interactions substantially curtail the extent of intramolecular charge transfer and thereby resulting distinct changes in visible color. Detection of multiple anions via distinct naked-eye color changing response is not very common in the literature and therefore will be beneficial for future development of new sensory systems.