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Tetragonal tungsten bronze (TTB)-type niobium–tungsten oxides are very interesting anode candidates for Na-ion battery applications due to their compositional flexibility, structural stability and large open-tunnel networks, which enable fast ion transport and pseudo capacitive behaviour. The present work introduces two TTB-type niobium tungstate anode materials, namely Nb18W16O93 (Nb dominant) and Nb7W10O47 (W dominant), prepared by a one-step hydrothermal method followed by low-temperature calcination at 800 °C. Furthermore, the low inherent electronic conductivity of the anode materials is effectively enhanced by incorporating the active materials with a carbon matrix to improve Na+-ion transport and storage. The presence of uniform carbon-coating surrounding the active particles in both materials is confirmed by high-resolution transmission electron microscopy images. At a current density of 10 mA g−1, carbon-coated Nb18W16O93 (NWO) delivered a higher reversible capacity of 163.95 mA h g−1 compared to that of carbon-coated Nb7W10O47 (WNO) (127.55 mA h g−1). Interestingly, the WNO material showed remarkable cycling stability over 420 cycles, at a current density of 100 mA g−1, recording a higher capacity retention of 81%, compared to NWO (69%). The promising electrochemical performance of the materials is related to structural defects, specific surface areas, charge transfer resistances during charge/discharge cycles and Na+-ion diffusion coefficients. Thus, the current work introduces niobium tungsten oxides as new and efficient anode candidates for sodium ion battery technology, and also enables safe, economical, and long-cycling Na-ion batteries, ultimately supporting the transition toward more sustainable energy technologies.

Sodium-ion batteries have emerged as the most promising alternative to lithium-ion batteries due to the advantages of high natural abundance, low cost, environmental friendliness, and retention of charge capacity at low temperatures. However, novel anode and cathode materials need to be developed. In this work, Sandia octahedral molecular sieves – a class of ion exchangers with the general formula, Na2Nb2−xMIVxO6−x(OH)x·H2O (M = Ti, Zr; x = 0.04–0.40) – are introduced as novel anode materials for sodium-ion battery applications. In this study, sodium niobium titanium oxide, Na2Nb1.6Ti0.4O5.6(OH)0.4·H2O (Na-NTO), is prepared by a simple hydrothermal method, followed by exchange of the Na+ ion in the SOMS structure by one of the eleven selected divalent or monovalent cations, after which the electrochemical properties of the ion-exchanged SOMS materials are investigated and compared with those of the unexchanged SOMS material. Exchanging sodium for divalent zinc delivered an enhanced specific capacity (196 mAh g−1 at 10 mA g−1vs. 89 mAh g−1 for Na-NTO) at every current density, whereas exchange for cadmium delivered a high capacity retention of 72% at 50 mA g−1 after 100 cycles. The enhanced electrochemical performance is related to their lower ionic radii (compared to Na+), higher selectivity, optimal pore size and higher Na+-ion diffusion coefficient. While the performances of the materials investigated here are comparatively low, the present work provides an in-depth study of the effect of partial ion-replacement on electrochemical performance.

Niobium-based oxide anode materials are promising anode materials for sodium ion batteries because of their high structural stability, safety, fast energy storage kinetics, and promising capacity. In this work, niobate compounds of the columbite type, ANb2O6 (A = Co2+ and Zn2+), prepared by a facile sol-gel method, are investigated as new anode materials for sodium ion batteries. The poor intrinsic electronic conductivity of the niobate anode materials is successfully overcome by coating the active materials with carbon in order to enhance Na-ion transport and storage. High-resolution transmission electron microscopy images reveal uniform coating of the carbon layer around the active particles to prevent agglomeration in both materials. While the carbon-coated material CoNb2O6 (CNO) at a current density of 25 mA g−1 delivered a high reversible capacity of 295 mA h g−1, the carbon-coated ZnNb2O6 (ZNO) material yielded 262 mA h g−1. However, the ZNO material delivered a significant cycling stability at a current density of 200 mA g−1, which corresponds to a capacity retention of 72% after 50 cycles. The difference in their electrochemical performances is related to the structural defects, specific surface areas, charge transfer resistances during charge-discharge cycles, Na+-ion diffusion coefficients, and the contribution of capacitive and diffusive behaviours to the total capacity. The present work not only introduces columbite compounds as anode materials with promising electrochemical properties but also provides insights into the development of potential anode materials for sodium ion battery technology and offers the foundation for designing new electrode materials with enhanced ion-diffusion pathways.

Potassium niobate, KNb3O8 (KNO) material is investigated as a potential anode material for sodium ion batteries owing to its layered structure and excellent electrochemical stability. However, the poor electrical conductivity of the material is addressed by surface modification with fluorine-doped carbon utilizing polyvinylidene fluoride as both a carbon and fluorine source. High resolution transmission electron microscopy results reveal that the active material is successfully embedded in the carbon matrix and X-ray photoelectron spectroscopy analysis confirms the tight attachment of carbon and fluorine bonding with the bulk material. As a result, the KNO@F-C material delivers a high reversible capacity of 173 mA h g−1 at a current density of 10 mA g−1, a superior rate performance of 137 mA h g−1 at 200 mA g−1 and a remarkable capacitance recovery rate (>100%). In addition, the coated material exhibits 90% capacity retention, demonstrating its long term cycling stability even after 200 cycles. The enhanced electrochemical performance of the coated sample over the pristine material is attributed to its large specific surface area, and a high Na+-ion diffusion coefficient, which facilitates a rapid transfer of electrons and improves grain-to-grain conductivity.

Developing monovalent anion-selective membranes (MAPMs) faces challenges, including the trade-off between flux and selectivity, membrane stability, and cost-effective fabrication. Overcoming these requires advanced material design and scalable techniques. Here, we introduce in situ interfacial polymerization (ISIP) to prepare MAPMs. Base membranes are synthesized via superacid polymerization and modified with anion channels and -NH2 groups. During ISIP, trimesoyl chloride reacts with surface -NH2 groups, forming a partially crosslinked structure with -COOH groups to regulate ion transport via electrostatic interactions. This results in low membrane resistance (4.7 Ω cm2) and selective transport of weakly hydrated ions (Cl−, Br−, NO3−), while strongly hydrated ions (SO42−, F−) face higher barriers. MAPMs demonstrate high performance, achieving a limiting current density (>90 mA cm−2), Cl− flux (1.98 mol m−2 h−1 at 5 mA cm−2), and selectivity (244 for Cl−/SO42−), confirming effective hydration dynamics control and balanced performance. Simulations reveal how charge distribution affects ion migration pathways.

A biobased anode material for sodium-ion batteries (SIBs) was prepared through the simple pyrolysis of Scotch pine cones (Pinus sylvestris, SPC), followed by a heteroatom doping modification. The resulting nitrogen-doped hard carbon exhibited a high reversible capacity of 273 mA·h·g-1 at a current density of 25 mA·g-1 compared to the undoped material (197 mA·h·g-1). X-ray diffraction analysis shows that the produced hard carbon from the biomass is highly amorphous in nature, and high-resolution transmission electron microscopy images reveal the presence of localized graphite-like structures that are found to be beneficial for the storage and transport of Na+ ions during charging/discharging. Experimental results demonstrated that the increased specific surface area (SBET = 424 m2·g-1), high micropore volume (0.177 cm3·g-1), and expanded interlayer spacing (>3.7 Å) and a high Na+-ion diffusion coefficient (3.08 × 10-16 cm2·s-1) facilitated the diffusion of sodium ions, leading to a high capacity retention of 80% after 250 cycles for the SPC-N material over the undoped one, SPC (71%). This study highlights the potential of low-cost, widely available biobased Scotch pine cones as an alternative anode material to enhance the sustainability of SIB production.

Recently, niobium-based oxides have attracted attention as anode materials for sodium-ion battery (SIB) applications due to their rate and stability performance. However, reports on T-phase Nb2O5 anode materials for SIB applications are rare. In this work, a simple and straightforward solid-state reaction to prepare a T-Nb2O5 anode material using niobic acid, Nb2O5.nH2O, is proposed. Further, the active particles are successfully embedded in a carbon matrix derived from citric acid to enhance the electrochemical performance, with scanning electron microscopy demonstrating improved grain-to-grain contact following carbon coating. As a result, the coated sample (NC-1, mass ratio of 1:1 between niobic acid and citric acid) exhibits a high reversible capacity of 240 mA.h g−1 at a current density of 25 mA g−1, compared to the uncoated sample (178 mA.h. g−1) due to increased surface area and porosity, better grain connectivity, and a more uniform carbon distribution. In addition, the carbon-coated sample displays a high rate capability of 180 mA.h g−1 at 200 mA g−1 and also delivers good cycling stability over 100 cycles with more than 99% Coulombic efficiency. The improved electrochemical performance is attributed to the presence of additional structural defects, enhanced particle contact, large pore volume, and high initial Coulombic efficiency.

Controlling and understanding charge state and metal coordination in carbon nanomaterials is crucial to harnessing their unique properties. Here we describe the synthesis of the well-defined fulleride complex [{(Mesnacnac)Mg}6C70], 2, (Mesnacnac)=HC(MeCNMes)2, Mes=2,4,6-Me3C6H2, from the reaction of the β-diketiminate magnesium(I) complex [{(Mesnacnac)Mg}2] with C70 in aromatic solvents. The molecular structure of complex 2 was determined, providing the first high-quality structural study of a complex with the C706− ion. In combination with solution state NMR spectroscopic and DFT computational studies, the changes in geometry and charge distribution in the various atom and bond types of the fulleride unit were investigated. Additionally, the influence of the (Mesnacnac)Mg+ cations on the global and local fulleride coordination environment was examined.

Many strains among spore-forming bacteria species are associated with food spoilage, foodborne disease, and hospital-acquired infections. Understanding the impact of environmental conditions and decontamination techniques on the metabolic activity, viability, and biomarkers of these spores is crucial for combatting them. To distinguish and track spores and to understand metabolic mechanisms, spores must be labeled. Staining or genetic modification are current methods for this, however, these methods can be time-consuming, and affect the viability and function of spore samples. In this work, we investigate the use of heavy water for permanent isotope labeling of spores and Raman spectroscopy for tracking sporulation/germination mechanisms. We also discuss the potential of this method in observing decontamination. We find that steady-state deuterium levels in the spore are achieved after only ∼48 h of incubation with 30% D2O-infused broth and sporulation, generating Raman peaks at cell silent region of 2200 and 2300 cm−1. These deuterium levels then decrease rapidly upon spore germination in non-deuterated media. We further find that unlike live spores, spores inactivated using various methods do not lose these Raman peaks upon incubation in growth media, suggesting these peaks may be used to indicate the viability of a spore sample. We further observe several Raman peaks exclusive to deuterated DPA, a spore-specific chemical biomarker, at e.g. 988 and 2300 cm−1, which can be used to track underlying changes in spores involving DPA. In conclusion, permanent spore labeling using deuterium offers a robust and non-invasive way of labeling bacterial spores for marking, viability determination, and characterising spore activity.

The present work evaluates the water oxidation catalytic activity of a Mn-based metal-organic framework (MOF), which we envisioned to reduce the oxygen evolution reaction (OER) overpotential because of its high electrical conductivity, facilitated by solvent-encapsulated structural features. The presence of Mn centers induces interesting magnetic features in the MOF, which exhibits impressive cryogenic magnetic refrigeration with a ΔSM value of 29.94 J kg^-1 K^-1 for a field change of ΔH = 5T at 2.3 K. To the best of our knowledge, the ΔSM value of the current system ranked the highest position among the published examples. The crystal structure aligns perfectly with the thematic expectations and features as many as ten metal-coordinated water molecules, forming an extensive web of a hydrogen-bonded network while facing toward the porous channel filled with another set of much-anticipated entrapped lattice water molecules. Such structural features are expected to manifest high proton conductivity, and detailed investigation indeed yields the best value for the system at 1.57 × 10^-4 S/cm at 95% humidity and 85 °C. In order to evaluate the thematic notion of a one-to-one relationship between OER and improved electrical conductivity, extensive electrocatalytic water splitting (WS) investigations were carried out. The final results show highly encouraging WS ability of the Mn-MOF, showing the electrocatalytic surface area value of the active species as 0.0686 F/g with a turnover frequency value of 0.043 [(mol. O₂) (mol. Mn-MOF)^-1 s^-1]. Another fascinating aspect of the current communication is the excellent synergy observed between the experimental WS outcomes and the corresponding theoretical data calculated using density functional theory (DFT). Consequently, a plausible mechanism of the overall OER and the role of the Mn-MOF as a water oxidation catalyst, along with the importance of water molecules, have also been derived from the theoretical calculations using DFT.