Ions In Sites Research Articles

Plasma-assisted preparation of NiCoAl-layered double hydroxides with alarge interlayer spacing on carbon cloth forelectrochemical deionization

Capacitive deionization has been considered an emerging desalination technique in recent years, especially for its economic and energy-saving characteristics for brackish water. However, there are currently few studies on chloride ion removal electrodes, and the slow desalination kinetics limits their development. Ar-NiCoAl- layered double hydroxide (LDH)@ACC materials with an increased interlayer spacing were prepared by the in-situ growth of NiCoAl-LDHs nanosheet arrays on acid-treated carbon cloth (ACC) and subsequent Ar plasma treatment. The carbon cloth suppresses the agglomeration of the NiCoAl-LDHs nanosheets and improves the electrical conductivity, while the plasma treatment increases the interlayer spacing of NiCoAl-LDHs and improves its hydrophilicity. This provides rapid diffusion channels and more interlayer active sites for chloride ions, achieving high desalination kinetics. A hybrid capacitive deionization (HCDI) cell was assembled using Ar-NiCoAl-LDHs@ACC as the chloride ion removal electrode and activated carbon as the sodium ion removal electrode. This HCDI cell achieved a high desalination capacity of 93.26 mg g−1 at 1.2 V in a 1000 mg L−1 NaCl solution, a remarkable desalination rate of 0.27 mg g−1 s−1, and a good charge efficiency of 0.97. The capacity retention remained above 85% after 100 cycles in a 300 mg L−1 NaCl solution at 0.8 V. The work provides new ideas for the controlled preparation of two-dimensional metal hydroxide materials with a large interlayer spacing and the design of high-performance electrochemical chlorine ion removal electrodes.

Twin graphene as an anode material for potassium‐ion battery: A first principle study

AbstractUsing density functional theory, we have investigated the usage of twin graphene as an anode material for potassium‐ion batteries (KIBs). Twin graphene demonstrates excellent structural and cycling stability, with minimal changes in lattice parameters and negative cohesive energy during K charge/discharge cycles. Notably, the host material (twin graphene) offers multiple stable adsorption sites for potassium ions. We even observed that the pristine twin graphene, which is a semiconductor, consequently becomes metallic upon potassium adsorption. Twin graphene provides a high theoretical capacity of 495.84 mAh/g, along with low diffusion barrier of 0.290 V for K diffusion. Furthermore, the high electrical conductivity and low open‐circuit voltage of the chosen host will definitely enhance its performance as a KIB material. The structural integrity of twin graphene is also retained with the adsorption of potassium ion, as checked through ab initio molecular dynamics simulation. These findings suggest that twin graphene may be considered as a promising anode material for KIBs.

A Photoionization Model for the Infrared Coronal Line Emission in the Classical Nova V1716 Scorpii

A near-infrared spectrum of nova V1716 Scorpii (PNV J17224490-4137160), a recent bright ( Vmax=7.3 mag), Fermi-LAT detected γ-ray source, was modeled using the photoionization code CLOUDY. Abundances were estimated for He, C, N, O, Si, Al, Mg, Fe, Ne, S, Ca, and P. Notably, P (a factor of 120) and N (a factor of 248) are highly overabundant. It was necessary to assume the ejecta consist of two components (with a cylindrical geometry): a dense component from which the bulk of the H, He, and neutral O i and N emission arises and a more diffuse component from which most of the coronal lines arise. Some of the coronal lines are found to originate from both the dense and diffuse components. The mass of the ejecta, including neutral and ionized gas, is ≃4.19 × 10−4 M ⊙. Our analysis indicates that in the case of V1716 Sco (which has a carbon–oxygen white dwarf), a fraction of 25% white dwarf matter rather than 50% is favored for the mixing between a white dwarf and the accreted envelope before the outburst. This mixing ratio is like that found for oxygen–neon novae where a 25% mixing fraction is also indicated. Helium hydride—the first molecule to form after the Big Bang—may have formed in the ejecta of V1716 Sco based on photoionization modeling. This prediction suggests that novae may be potential formation sites of this important molecular ion.

CD-MOF-1 Growth on Polysaccharide Gels through Only C2-OH/C3-OH or C5-O/C6-OH Group Formed Four-Coordinated K+ Ions for Developing Porous Biogels.

The γ-cyclodextrin (γ-CD) metal-organic frameworks (CD-MOF-1) consist of γ-CD and potassium (K+) ions through coordinating an eight-coordinated K+ ion with two C5-linked oxygen and C6-linked hydroxyl (C5-O/C6-OH) groups in the primary faces of adjacent γ-CD units and two C2- and C3-linked hydroxyl (C2-OH/C3-OH) groups in the secondary faces. Herein, we found polysaccharide gels with only C2-OH/C3-OH or C5-O/C6-OH groups in pyranoid rings can form four-coordinated K+ ions and then coordinate γ-CD in a KOH solution for CD-MOF-1 growth. Exposure of C2-OH/C3-OH or C5-O/C6-OH groups in polysaccharide gels is important to form active four-coordinated K+ ions. Mechanism supporting this work is that four-coordinated K+ ion sites are first formed after coordinating C2-OH/C3-OH groups in pectin and then coordinating C5-O/C6-OH groups in the primary faces of γ-CD units. Alternatively, four-coordinated K+ ions with C5-O/C6-OH groups in chitosan can coordinate the C2-OH/C3-OH groups in the secondary faces of γ-CD units. Mechanism of CD-MOF-1 growing on pectin and chitosan gels through the proposed four-coordinated K+ ions is also universally applicable to other polysaccharide gels with similar C2-OH/C3-OH or C5-O/C6-OH groups such as alginate gel. Based on this mechanism, we developed pectin and chitosan gel-based CD-MOF-1 composites and exemplified applications of them in antibacterial and organic dye removal. To help future research and applications of this mechanism, we share our theoretical assumption for further investigations that any matrices with an ortho-hydroxyl carbon chain or ortho-hydroxyl ether structures may form four-coordinated K+ ions for CD-MOF-1 growth. The proposed mechanism will broaden the development of novel CD-MOF-1 composites in various fields.

The hyper-crosslinked aniline polymer@MOFs hybrid materials reinforced with active ionic sites for efficient and fast Cr(VI) removal

The adsorption of toxic metal ions by composite materials of metal–organic frameworks (MOFs) has attracted significant attention in recent years. In this work, a series of hybrid materials HPAN@M−x consisting of protonated hyper-crosslinked aniline polymer (HPAN) and MOFs were synthesized via the Friedel-Crafts reaction between aniline and dimethoxymethane in the presence of MIL-101(Cr), followed by protonation with hydrogen bromide. These hybrid materials exhibited enhanced adsorption rate and capacity for Cr(VI) ions compared to both individual MIL-101(Cr) and HPAN. The effects of the ratio of aniline to MIL-101(Cr), solution pH, adsorption temperature, impurity ions on the removal of Cr(VI) ions were systematically investigated. Notably, HPAN@M−b not only achieved an adsorption capacity up to 290.9 mg·g−1 in 7 min but also exhibited excellent cycling stability by maintaining a high Cr(VI) removal efficiency of 95.6 % after five cycles. The enhanced adsorption performance is attributed to the synergistic effect between MIL-101(Cr) and HPAN. Mechanism studies indicated that the removal for Cr(VI) ions involved a combination of ion exchange and electrostatic adsorption processes. Additionally, the desorbed Cr(VI) ions were transformed into added-value barium chromate (BaCrO4) precipitates, allowing for resource utilization of Cr(VI) ions. This study represents a significant advancement towards developing MOFs-based hybrid materials for practical treatment of chromium-containing wastewater.

The dual active sites reconstruction on gelatin in-situ derived 3D porous N-doped carbon for efficient and stable overall water splitting

The exploration of bifunctional electrocatalysts with high activity, stability, and economy is of great significance in promoting the development of water splitting. Herein, a dual active sites heterostructure NiCoS/NC was designed to be derived in situ on 3D N-doped porous carbon (NC) using gelatin as a nitrogen and carbon source. The characterization of experiments suggests that nanoflower-like Ni2CoS4 (abbreviated as NiCoS) was randomly distributed on the NC substrate, and the sheet-like NC formed a highly open porous network structure resembling a honeycomb, which provided more accessible active sites for electrolyte ions. In addition, the special nanostructures of the catalyst materials help to promote the surface reconstruction to the real active substance NiOOH/CoOOH, and the double active sites synergistically reduce the overpotential of OER and improve its kinetics. DFT (Density-functional theory) calculations reveal the electronic coupling of NiCoS/NC in atomic orbitals, modulation of electrons by the heterointerface and N-doping, and synergistic effect of dual active sites improving the inherent catalytic activity. The NiCoS/NC composite electrocatalyst exhibited a 177 mV small OER overpotential and a 132 mV small HER overpotential with Faraday efficiencies as high as 96 % and 98 % at 10 mA cm−2 current density. In the two-electrode system, it also requires only an ultra-low voltage of 1.52 V to achieve a 10 mA cm−2 current density, and it shows excellent long-term water splitting stability. This provides a new idea for the development of transition metal-based bifunctional electrocatalysts.

An active site mutation induces oxygen reactivity in D-arginine dehydrogenase: A case of superoxide diverting protons

Enzymes are potent catalysts that increase biochemical reaction rates by several orders of magnitude. Flavoproteins are a class of enzymes whose classification relies on their ability to react with molecular oxygen (O2) during catalysis using ionizable active site residues. Pseudomonas aeruginosa D-arginine dehydrogenase (PaDADH) is a flavoprotein that oxidizes D-arginine for P.aeruginosa survival and biofilm formation. The crystal structure of PaDADH reveals the interaction of the glutamate 246 (E246) side chain with the substrate and at least three other active site residues, establishing a hydrogen bond network in the active site. Additionally, E246 likely ionizes to facilitate substrate binding during PaDADH catalysis. This study aimed to investigate how replacing the E246 residue with leucine affects PaDADH catalysis and its ability to react with O2 using steady-state kinetics coupled with pH profile studies. The data reveal a gain of O2 reactivity in the E246L variant, resulting in a reduced flavin semiquinone species and superoxide (O2•-) during substrate oxidation. The O2•- reacts with active site protons, resulting in an observed nonstoichiometric slope of 1.5 in the enzyme's log (kcat/Km) pH profile with D-arginine. Adding superoxide dismutase results in an observed correction of the slope to 1.0. This study demonstrates how O2•- can alter the slopes of limbs in the pH profiles of flavin-dependent enzymes and serves as a model for correcting nonstoichiometric slopes in elucidating reaction mechanisms of flavoproteins.

Molecular Insights into the Effect of Cholesterol on the Binding of Bicarbonate Ions in Band 3 Protein.

Band 3, or anion exchanger 1 (AE1), is one of the indispensable transmembrane proteins involved in the effective respiratory process of the human body and is primarily responsible for the exchange of bicarbonate and chloride anions across the plasma membrane of erythrocyte. However, the molecular mechanism of ion transport of Band 3 is not completely understood, yet. In this work, we systematically investigate the key binding sites of bicarbonate ions in Band 3 and the impact of cholesterol (CHOL) in lipid bilayers on bicarbonate ion binding using all-atom molecular dynamics (MD) simulations. We examine the dynamics of interactions of bicarbonate ions with Band 3 in the microsecond time scale and calculate the binding free energy of the anion in Band 3. The results indicate that the residue R730 of Band 3 is the most probable binding site for bicarbonate ions. CHOL enhances the bicarbonate ion binding by influencing the conformational stability of Band 3 and compressing the volume of the Band 3 cavity. These findings provide some insights into the bicarbonate ion binding in Band 3 and are helpful for understanding the anion exchange of Band 3.

Heavy metals removal in a graphene engineered concrete-based filter column

In this study, crushed aggregate surfaces were coated with reduced graphene oxide (RGO) using a chitosan-derived solution and included in porous concrete-based filter column samples to improve heavy metal removal. The RGO coating strengthened the aggregate and cement interfaces, thus improving the compressive strength of these samples by up to 18 %. The removal of lead and copper in samples containing RGO coated aggregate (GCA) operated with a minimum hydraulic load was found to be 97 % and 92 %. Increasing the hydraulic load reduced this heavy metal removal, but the presence of GCA increased the active sites for heavy metal ions to immobilize, leading to improved copper removal under such operating conditions. Calcium ions from the cement hydrates were found to leach from the concrete matrices during such a wastewater passage. This leaching of calcium ions was determined to be relatively lesser in RGO decorated concrete samples, pointing out the positive effects of GCA on the resistance of the concrete matrices to aggressive chemicals. Clay particles containing highly turbid water were also passed through these concrete samples to examine the effects on the infiltration rate. Clay particles were found to clog pores, marginally reducing the infiltration rate. Concrete-based water filters are easy to operate and have low maintenance requirements, and industries responsible for heavy metal pollution in aquatic environments can widely adopt them instead of complex treatment methods.

Amidoximated‐Wood Derived Carbons as Advanced Self‐Standing Electrodes for Supercapacitor and Water Splitting

AbstractWood‐derived carbons demonstrate great potential as self‐standing electrodes in energy storage/conversion applications, including supercapacitors and water‐splitting devices. However, the key challenge remains the rational customization of surface functionalities for optimized performance. This study introduces an innovative approach to self‐standing wood‐derived carbons with tailored nitrogen and metal functionalities. In contrast to traditional impregnation techniques, which offer limited precision in surface modification, this approach entails the intentional attachment of amidoxime groups to the wood substrates. These groups serve as nitrogen sources, and create abundant surface anchoring sites for metal ions due to the chelation between the amidoxime groups and metals. The resulting carbons feature uniform and high dispersion of nitrogen and metal functionalities, along with a distinctive hierarchical porosity combining interconnected open channels with abundant mesopores. As a proof‐of‐concept, different metals are incorporated (i.e., Mn, Co, Ni) into the amidoximated‐wood precursors, and the resulting self‐standing carbons showcase excellent performance in both supercapacitors and water‐splitting applications. Leveraging the specific chelating ability of amidoxime groups toward metal ions, this strategy holds great potential as a generic approach to systematically tailoring the surface functionalities of carbon‐based materials for various electrochemical energy storage/conversion processes.

Air-mediated phosphoric acid activation strategy for preparation of oxygenated functional groups rich activated carbon for capacitive deionization

Atmosphere during H3PO4 activation is vital to the texture structure and surface-interface properties of activated carbon (AC), but the researches are way out of sufficiency. In this work, it is found that the air in the H3PO4 activation process is not only conducive to the introduction of more-oxidized oxygenated functional groups on ACs, but also beneficial to the formation of micropores rather than mesopores. Besides, as the air content increases in H3PO4 activation, the ACs’ ash, phosphorous content and conductivity reduce, but their wettability, disorder degree and defect number increase. In addition, the potential of zero charge of the as-prepared ACs is positively correlated with the O-CO content, which show a pattern of first increasing and then decreasing with the increase of air content. Benefit from the improved hydrophilicity, electrolyte-affinity, additional adsorption sites for sodium ions, the optimal AC exhibits excellent salt adsorption capacity of 12.08 mg g−1 and good cycling stability at 1.0 V in single-pass capacitive deionization. This work not only establishes a novel and effective method for regulating the texture structure and surface properties of ACs, but also provides promising cathode candidates for capacitive deionization application.

Effects of pH-varying thermal modification on sewage sludge: A focus on releasing nitrogen- and phosphorus-containing substances

Sewage sludge is promising for the recovery and utilisation of nutrient components, but its complex nature hinders the release of these components. The combination of pH and thermal modifications shows promise for the release of nutrient components from sludge. However, comprehensive studies on the full spectrum of pH levels and corresponding mechanisms of pH-varying thermal modification are lacking. In this study, the main nutrient components, physicochemical properties, molecular structure, and noncovalent interactions of sludge were comprehensively investigated through pH-varying thermal modification (within a pH range of 2.0 to 12.0 under the same thermal condition). The experimental results showed that the release of main organics, particularly nitrogen (N)-containing organics, was well-fitted, with a tick-like function (R2: 0.74–0.96). The thermal protons exhibited a notable accumulative mutagenic effect on the N-containing organics release, while the thermal hydroxyl ions had a more direct effect, as revealed by the changes in multivalent metals and molecular structures with the protonation–deprotonation of carboxyl groups. The driving force for the release of N-containing organics was identified as the fluctuation of electrostatic interactions at the solid–liquid interface of the sludge. However, the release of phosphorus (P)-containing substances exhibited a contrasting response to that of N-containing substances with varying pH, likely because the reaction sites of thermal protons and thermal hydroxyl ions for P-containing substances were different. Moreover, high concentrations of thermal protons and hydroxyl ions collapsed the Lifshitz–van der Waals interactions of sludge, resulting in a decrease in viscoelasticity and binding strength. These propositions were further confirmed through statistical analyses of the main indicators of the main nutrient components, physicochemical properties, and noncovalent interactions of sludge. These findings can provide a basis for optimising characteristic-specific methods to recovery nutrient components (N/P) from sludge.

A rigid free-standing supercapacitor electrode material made from fat coal-based activated carbon foam

A free-standing electrode material is a competitive candidate for supercapacitor due to its excellent capacity and volumetric energy density. Currently, most of the studies are focused on the preparations and performances of flexible free-standing electrode materials, whereas few on the development of rigid free-standing electrode materials. Herein, a vitrinite concentrate of fat coal is used as a raw material and carbon black as an addition agent to prepare a carbon foam by way of high-pressure pyrolysis. The prepared carbon foam is activated by KOH solution to further achieve an activated carbon foam by which we have fabricated a rigid free-standing electrode material. The assembled symmetric device with the rigid free-standing electrode material demonstrates an extremely high areal specific capacitance of 2304.41 mF cm−2 at 4 mA cm−2, an outstanding cycling stability of 100 % after 40 000 cycles, and an excellent volume energy density of 10.23 mWh cm−3 at 31.78 mW cm−3. These fascinating electrochemical performances of the electrode material are attributed to unique 3D interconnected porous structure of the activated carbon foam. The micron-sized 3D interconnected pores facilitate the transport of electrolyte ions within the electrodes. Meanwhile, micropores on the 3D interconnected pore wall provide abundant active sites for electrolyte ions.

Side-chain type PPO based anion exchange membrane with steric hindrance containing dual conduction sites

Appropriate addition of cation transport sites while maintaining the good mechanical properties of anion exchange membranes (AEMs) can effectively improve the hydroxide ion conductivity. Therefore, a series of poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) based side-chain type AEMs containing dual conduction sites are successfully prepared. The 4-(4-dimethylaminostyryl)-1-methylpyridinium (DASP) side chains are grafted to brominated PPO at different ratios, which is confirmed by Fourier transform infrared spectroscopy (FT-IR). Analysis of the microscopic morphology reveals a distinct microscopic separation pattern of hydrophilic/hydrophobic regions, which provides efficient channels for the transport of hydroxide ions. The ionic conductivity of the PPO-DASP13 membrane reaches 89.97 mS/cm at 80 °C, which is benefited from the double cationic groups contained in the side chains, providing more conduction sites for hydroxide ions. Meanwhile, the tensile strength of membranes range from 17.83 MPa to 29.38 MPa, which have good mechanical properties. The ionic conductivity of all membranes retain about 70 % after a 800 h long-term alkali resistance test, which is related to the steric hindrance contained in the side chain structure and the conjugated system. Furthermore, the single cell based on PPO-DASP13 membrane with the highest ionic conductivity achieves a peak power density of 347.7 mW/cm2 in H2-air (CO2-free) at 60 °C.

Investigation of the adsorption behaviour of toxic heavy metals and bacteria on two allotropes of low dimensional boron nitride: Implications for detection and elimination

In this research, the focus was on two 2D allotropes of boron nitride (BN), specifically Haeck-BN and Twin-BN. They exhibit unique structural and electronic characteristics, making them suitable for sensing applications. High surface area materials offer numerous affinity sites for heavy metal ions and toxic molecules. Using density functional theory (DFT), the adsorption mechanisms of various contaminants in gas (solvent) phase on both pristine and doped Haeck-BN and Twin-BN were investigated. Pronounced adsorption of arsenic (As) and lead (Pb) was observed on pristine Twin-BN sheets, with adsorption energies of −2.83 eV (−2.86 eV) and −2.03 eV (−2.39 eV), respectively. Haeck-BN showed weaker interactions, with adsorption energies of −1.48 eV (−1.55 eV) for As and −0.64 eV (−0.92 eV) for Pb. Significant adsorption of specific amino acids, integral components of bacterial cell walls, was noted on both pristine and silver-modified sheets. The electronic properties showed significant shifts upon molecular adsorption, confirming their sensitivity towards foreign contaminants. The high adsorption energies of amino acids suggest potential applications in efficient bacterial inactivation for water purification. While real-world scenarios pose challenges, the calculations provide valuable insights for potential use of these nanosheets in advanced water purification membrane technology.

Study on Water Splitting of the 214-Type Perovskite Oxides LnSrCoO4 (Ln = La, Pr, Sm, Eu, and Ga).

We present a study on the electrocatalysis of 214-type perovskite oxides LnSrCoO4 (Ln = La, Pr, Sm, Eu, and Ga) with semiconducting-like behavior synthesized using the sol-gel method. Among these five catalysts, PrSrCoO4 exhibits the optimal electrochemical performance in both the oxygen evolution reaction and the hydrogen evolution reaction, mainly due to its larger electrical conductivity, mass activity, and turnover frequency. Importantly, the weak dependency of LSV curves in a KOH solution with different pH values, revealing the adsorbate evolving mechanism in PrSrCoO4, and the density functional theory (DFT) calculations indicate that PrSrCoO4 has a smaller Gibbs free energy and a higher density of states near the Fermi level, which accelerates the electrochemical water splitting. The mutual substitution of different rare-earth elements will change the unit-cell parameters, regulate the electronic states of catalytic active site Co ions, and further affect their catalytic performance. Furthermore, the magnetic results indicate strong spin-orbit coupling in the electroactive sites of Co ions in SmSrCoO4 and EuSrCoO4, whereas the magnetic moments of Co ions in the other three catalysts mainly arise from the spin itself. Our experimental results expand the electrochemical applications of 214-type perovskite oxides and provide a good platform for a deeper understanding of their catalytic mechanisms.

Precise Construction of Nitrogen-Enriched Porous Ionic Polymers as Highly Efficient Sulfur Dioxide Adsorbent.

Porous ionic polymers with unique features have exhibited high performance in various applications. However, the fabrication of functional porous ionic polymers with custom functionality and porosity for efficient removal of low-concentration SO2 remains challenging. Herein, a novel nitrogen-enriched porous ionic polymer NH2Py-PIP is prepared featuring high-content nitrogen sites (15.9wt.%), adequate ionic sites (1.22mmolg-1), and a hierarchical porous structure. The proposed construction pathway relies on a tailored nitrogen-functionalized cross-linker NH2Py, which effectively introduces abundant functional sites and improves the porosity of porous ionic polymers. NH2Py-PIP with a well-engineered SO2-affinity environment achieves excellent SO2/CO2 selectivity (1165) and high SO2 adsorption capacity (1.13mmolg-1 at 0.002bar), as well as enables highly efficient and reversible dynamic separation performance. Modeling studies further elucidate that the nitrogen sites and bromide anions collaboratively promote preferential adsorption of SO2. The unique design in this work provides new insights into constructing functional porous ionic polymers for high-efficiency separations.

Analysis of the adsorption and fixation process of ammonium nitrogen in arable soil by biochar based on molecular dynamics simulation

The ammonia nitrogen in arable land soil is susceptible to environmental and anthropogenic influences, leading to nutrient loss. This study utilized indoor soil column leaching experiments, combined with adsorption mathematical models, traditional characterization methods, and molecular dynamics simulation methods, to analyze the effects of biochar on changes in ammonium ions in different soil layers and leachate of arable land soil. The study found that applying biochar at a ratio of 10 % to arable land soil could effectively increase the ammonium ion content in the 0–10 cm soil layer by 1.57–2.36 times and reduce loss by 44.83–72.27 %. The adsorption and fixation process of biochar is controlled by electrostatic attraction and ion exchange processes. Interactions between molecules, electrostatic forces, and system internal energy also have certain effects on the process. Near the structure of C6H12O6, there are low-energy adsorption sites for ammonium ions, which can provide the energy required for electrostatic attraction. Structures such as C5H10O5, C-S-H, C-SO3, and C4H7NO4 respectively play roles in physical adsorption or chemical adsorption through displacement reactions, electron exchange, and other forms. The adsorption free energy is −394,590.84 kcal/mol, indicating stable adsorption and a process that tends to interact with the biochar surface. This study addresses issues such as the easy loss of ammonia nitrogen in arable land soil and the unclear adsorption mechanism of biochar on ammonium ions, providing a theoretical basis for the field of environmental science.

Dual regulation of particle size and surface structure of SrVO3 for high volumetric capacity

Perovskite SrVO3 stands out as a promising anode material for lithium-ion batteries due to its inherent redox activity, excellent electrical conductivity, and structural adaptability. Despite these advantages, challenges persist, such as in achieving high tap density and volumetric specific capacity. In this study, we overcome these challenges by finely regulating particle size and constructing a tailored surface structure for SrVO3. The implementation of ball milling during the synthesis process proves to be a simple yet highly efficient method for simultaneously tailoring particle size and in-situ creating an amorphous layer on SrVO3 particles. The reduction in particle size not only facilitates enhanced electron and ion transport but also significantly improves the tap density of SrVO3, increasing it from 2.61 to 3.15 g cm−3. The in-situ construction of an amorphous layer introduces a multitude of defects and high valence V5+. These defects serve as active sites for lithium ions, while the V5+ species contribute to increased electron transfer, collectively resulting in a high gravimetric specific capacity. The engineered SrVO3 anode delivers an impressive volumetric capacity of 1134 mAh cm−3 at 0.1 A g−1, surpassing both pristine SrVO3 (733 mAh cm−3) and commercial graphite anode (∼460 mAh cm−3).

Effects of La-Mn co-substitution on the structure and magnetic properties of M-type strontium hexaferrite

Research into enhancing the magnetic properties of permanent ferrite using ion substitution techniques has continued, particularly concerning replacing commercially available La-Co co-substitution ferrite with larger magnetic anisotropy and lower prices. Mn ions with larger magnetic moments have become one of the options. In this work, Sr1-xLaxFe11.6-xMnxO19 (0 ≤ x ≤ 0.5) with equal substitution of La-Mn was synthesized by the conventional ceramic route. X-ray diffraction analyses indicated that the upper limit of La-Mn concentration was 0.4. The lattice constant a increases and c decreases with increasing La-Mn concentrations. With the increase of La-Mn concentrations, Ms reaches the highest value of 80.52 emu/g (x = 0.2) at 300 K. As evidenced by Raman spectroscopy, the substitution sites of Mn ions in the ferrite lattice altered with the substitution concentration, and the substitution tendency was 4f2 > 12 k + 2a > 4f1. In addition, La-Mn substitution affects the inherent magnetic properties such as HA and Tc of the samples, which has a reference for further improvement of permanent ferrites.