Dopant Ions Research Articles

Tailoring Li4Ti5O12 Performance in Li-Ion Batteries with a Focus on Rate Capability: Recent Advances on Ion Doping, Morphology Control, and Composite Formation

Tailoring Li4Ti5O12 Performance in Li-Ion Batteries with a Focus on Rate Capability: Recent Advances on Ion Doping, Morphology Control, and Composite Formation

Synthesis, Structure, and Electrochemical Performance of Bi-induced Stabilization of MnO2 Cathodes for Use in Highly Acidic Aqueous Electrolytes (pH

MnO2 cathode materials are widely studied in alkaline and neutral aqueous electrolytes. In these mediums, the MnO2 cathode shows suboptimal performance limited by dissolution and electrochemically inactive compound formation, leading to capacity fading. This study explores the enhancement of MnO2 cathode performance through Bi3+ ion doping (0, 1, 2.5, 5, and 10mol%) in a highly acidic electrolyte (pH < 2). By incorporating up to 10mol% Bi ions into the MnO2 structure, we significantly improved specific capacity and capacity retention stability. Energy-dispersive X-ray spectroscopy (EDX) analysis revealed a uniform dispersion of Bi3+ ions throughout the MnO2 cathode after electrochemical cycling, contributing to performance enhancements. X-ray photoelectron spectroscopy (XPS) results indicated that Bi3+ ion concentration from 1 to 10mol% stabilises Mn3+ within the MnO2 lattice. Also, Bi3+ ion doping promotes the formation of a 2×2 tunnel structured α-MnO2 phase. Electrochemical impedance spectroscopy results demonstrated a reduction in double-layer and overall bulk capacitance. These findings suggest that Bi3+ ion doping effectively enhances MnO2 electrochemical performance and could enhance its use in aqueous metal-ion batteries.

Synthesis and Characterization of Ni2+- Zr4+ Doped Ba-Ca M-Type Hexaferrites using Sol-Gel Auto-Combustion Method

This work aims to study the effect of Zr-Ni dopant on the structure and traits of M-type barium calcium hexaferrites (BaCaM). For the first time, Ba0.8Ca0.2ZrxNixFe12-2xO19 (0.0≤ x ≤1.0) samples are synthesized employing the SGACM (sol-gel auto-combustion method). The pure phase formation of BaCaM was established by XRD data Rietveld refinement. An augmentation in both the lattice parameters (‘a’ as well as ‘c’) owing to the higher ionic radii of dopant ions as compared to Fe3+ shows that Ni2+ and Zr4+ions were successfully swapped with Fe3⁺. The "c/a" ratio lies between 3.93-3.96 disclosing that the synthesized materials possess an M-type hexagonal ferrite structure. The reduction in crystallite with an increase in doping level might be due to lattice strain generated by the larger size of Ni2+ and Zr4+ dopant ions. The presence of two bands in the wavenumber range of 400 to 880 cm-1 in FTIR spectra corresponds to the Fe–O stretching in octahedral and tetrahedral locations. The Raman peaks widen without any shifting of the peak with an increment in Ni2+-Zr4+ ions contents revealing that Ni2+-Zr4+ are incorporated into BaCaM without changing its crystal structure. According to the M-H plots Ms value enhance from 24.94 (x= 0.00) to 36.84 emu/g (x= 0.60) and beyond x=0.60, Ms values drop with an increment in Ni2+-Zr4+substitution level. A broad coercivity range lies between 4858 Oe (x = 0.0) to 653 Oe (x = 1.0), decreasing monotonically with substitution in Ni2+-Zr4+. All the synthesized material exhibits a reduction in dielectric constant value as frequency increases. Ni-Zr-doped BaCaM materials could be a suitable candidate for magnetic recording media and microwave absorber applications.

Dy doped calcium silicates synthesized using agro-food wastes and conventional chemicals as resources: a comparative study

Based on an earlier study, a mimic composition 38SiO2-60CaO-0.5Dy2O3-0.2Na2O-1MgO-0.1Al2O3-0.1TiO2-0.1Fe2O3 (wt.%) are synthesized by solid-state reaction method. The structural, morphological, and optical properties of the synthesized sample presented in this study are compared with the corresponding properties of a similar sample derived from rice husk ash and eggshell powder as resources. The conventional chemicals derived sample are multi-phasic, containing β−Ca2SiO4, γ−Ca2SiO4, Ca3Si2O7, and CaFeO3 phases, and the CaO/SiO2 ratio was believed to be affecting the room temperature stabilization of the β phase. Field emission scanning electron microscopy images showed that twinned particles, cracks, and edge dislocations were present in the synthesized sample. The presence of precipitates in the micrographs indicated that Dy ions were segregated on the surface of the sample. The optical bandgap of the samples was 3.7 eV, as calculated by diffuse reflectance spectroscopy. The photoluminescence emission spectrum contained characteristic emission peaks of the Dy3+ ions. Apart from these, additional peaks were observed due to the titanium ions present in the sample. Understanding the properties of calcium silicates containing multiple dopant ions is important to develop a white light-emitting diode. The properties of the mineral-derived sample are compared to those of the agro-food waste-derived similar sample.

A Practical Guide to Metal Ions Dynamic Nuclear Polarization in Materials Science

In this protocol we outline the practical aspects and methodology for performing metal ions-based dynamic nuclear polarization (MI-DNP), focusing on materials science applications. In MI-DNP polarization is transferred from unpaired electrons of paramagnetic metal ions to nearby nuclear spins, thereby increasing the sensitivity of NMR spectroscopy. The protocol encompasses detailed steps for i) selecting suitable metal ions dopants based on chemical, structural and electron paramagnetic resonance (EPR) considerations, ii) characterizing the concentration, homogeneity and EPR properties of the dopant and iii) performing the MI-DNP experiment itself, including optimization of the field position and reliable assessment of the DNP enhancement factors. By adhering to this protocol, the interested reader can implement the MI-DNP approach in an efficient way, facilitating spectroscopic studies of functional materials.

HUVECs’ Expressway Based on Magnesium Ion Doped Hierarchical Scaffold for Rapid Angiogenesis and Bone Ingrowth

AbstractDelayed union or nonunion remains an extremely challenging predicament even after the application of currently available engineering scaffolds for the treatment of critical‐sized bone defects. The angiogenesis throughout the artificial bone repair scaffold to achieve “angiogenic‐osteogenic coupling” is regarded as an effective approach to solving this issue. The newly formed blood vessels can accelerate the supply of oxygen and nutrients, thereby triggering subsequent bone regeneration. Therefore, scaffolds featuring an angiogenic microenvironment that promotes cell adhesion and migration should be designed for superior bone repair. Herein, a magnesium ion‐doped hierarchical scaffold is fabricated using a polymer blend system of chitosan/polyethyleneimine with inherent micro‐phase separation and complexation. Due to the microscopic sea‐island structure and the stable doped magnesium ions, the cell adhesion behavior underwent a significant transformation. Meanwhile, the pathways related to cell adhesion, migration, and angiogenesis are activated, and the critical target thrombospondin 1 is upregulated. Consequently, the cell adhesion capacity is augmented, 6 times the cell migration rate is attained, and the angiogenesis of human umbilical vein endothelial cells is significantly expedited. Eventually, rapid bone ingrowth and satisfactory bone defect repair are approximated in vivo, making the composite scaffold a promising clinical candidate for bone engineering.

Recent progress and perspectives of advanced Ni-based cathodes for aqueous alkaline Zn batteries

Rechargeable aqueous alkaline Zn-Ni batteries (AZNBs) are considered a potential contender for energy storage fields and portable devices due to their inherent safety, high output voltage, high theoretical capacity and environmental friendliness. Despite the facilitated development of AZNBs by many investigations, its practical application is still restricted by inadequate energy density, sluggish kinetics, and poor stability. Therefore, Ni-based cathodes with boosted redox chemistry and enhanced structural integrity is essential for the high-performance AZNBs. Herein, this review focus on critical bottlenecks and effective design strategies of the representative Ni-based cathode materials. Specifically, nanostructured optimization, defect engineering, ion doping, heterostructure regulation and ligand engineering have been employed from the fundamental aspects for high-energy and long-lifespan Ni-based cathodes. Finally, further exploration in failure mechanism, binder-free battery configurations, practical application scenarios, as well as battery recycling are considered as valuable directions for the future development of advanced AZNBs.

Improvement of microstructure and dielectric properties of Zn1.8SiO3.8 ceramics by doping with rare earth elements (La, Pr, Nd, Sm)

The current crucial focus is improving the performance of microwave dielectric ceramics, aiming for a low dielectric constant and minimal dielectric loss for millimeter-wave applications. In this study, we successfully synthesized Zn1.8SiO3.8-RO (R=La, Pr, Nd, Sm) microwave dielectric ceramics, namely ZLSO, ZPSO, ZNSO, and ZSSO, using the solid-state reaction sintering method. X-ray diffraction peaks indicated that the main phase matched the standard Zn2SiO4 diffraction peaks. As the dopant ion radius increases from Sm³⁺ to La³⁺, the diffraction peak shifts to a lower angle and the cell volume increases. Scanning electron microscopy revealed that the ZLSO, ZPSO, ZNSO, and ZSSO ceramics displayed denser and more uniform grain shape, along with a significant decrease in the densification temperature (1200°C-1250°C) compared to the Zn1.8SiO3.8 (1350°C-1400°C). Further research indicated that substituting rare earth ions maintained a low εr while effectively increasing the Q×f values. The specific properties are as follows: ZLSO: εr = 7.06, Q × f = 59,314GHz, τf = -25.00 ppm/℃; ZPSO: εr = 7.02, Q × f = 111,184GHz, τf = -17.77 ppm/℃; ZNSO: εr = 7.02, Q × f = 127,711GHz, τf = -33.52 ppm/℃; ZSSO: εr = 7.06, Q × f =108,435GHz, τf = -22.9 ppm/℃. Among them, ZNSO exhibited the best microwave dielectric performance. The research not only effectively produces microwave dielectric ceramics with outstanding performance but also systematically uncovers the distinct effects of rare earth elements doping on the dielectric properties of silicate systems. This provides the theoretical groundwork for utilizing 5G millimeter wave bands.

Surface morphology modulation in multilayer scaffolds via ion doping for bone tissue engineering

AbstractThis work proposes the use of multilayer scaffolds as a strategy for developing biomimetic structures for bone tissue regeneration. The scaffolds consist of a glass–ceramic core composed of CaSiO3/Ca2P6O17, which provides mechanical properties of 2.3 MPa and a total porosity of ∼74%. To modify the surface morphology a double bioactive coating consisting of Ca3(PO4)2/CaSiO3 doped with Na+ and K+, along with varying amounts of Mg2+ (0–0.75 g MgCO3) was carried out giving a total porosity of 89.8%. The resulting scaffolds were assessed for in vitro bioactivity according to ISO 23317. After immersion in SBF, the W‐05 scaffolds displayed diverse surface morphologies: square HA structure (W‐05‐3D), hollow HA spheres (W‐05‐7D) and smooth HA layer (W‐05‐21D). Cell viability of 3T3 fibroblasts exposed to W‐05 scaffolds in direct and indirect assays at concentrations of 15 and 30 mg/mL was assessed according to ISO 10993–5. Initially, cell proliferation decreased compared to controls, but differences became non‐statistically significant after 72 h. Hollow spheres (W‐05‐7D) enhanced cell viability compared to other morphologies and plastic controls. Additionally, degradation products of W‐05 stimulated cell division, underscoring scaffold biocompatibility.

Efficient photocatalytic degradation of tetracycline hydrochloride by Fe-TiO2/MIL-101(Cr) nanocomposites under visible light

The misuse of antibiotics, including tetracycline hydrochloride (TCH), can easily lead to drug resistance and the decline of human immunity, which is extremely harmful to human health. In this paper, TiO2 was modified using two different techniques: semiconductor composite and metal ion doping. Fe-TiO2/MIL-101 (Cr) nanocomposite photocatalyst (FTM-x) was effectively prepared by solvothermal method and used for the degradation of TCH in water under visible light. The performance of ternary composite materials, in comparison to single or binary compounds, are improved by using an easy and convenient hydrothermal technique. Among them, FTM-2 showed efficient photodegradation and structural stability. After 120 min in visible light, FTM-2 removed 95.5 % of TCH, and the removal was maintained at 85 % after 4 cycles. The composite FTM-x was characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Raman, which proved the successful synthesis of the composite. Photoelectrochemical and photoluminescence (PL) analyses were used to examine the photoelectric properties of the prepared photocatalysts. The results suggested that optimizing the composites' photoresponse and electron-hole separation could be linked to improving the photocatalytic performance. The photocatalytic activity of superoxide radicals (O2−) and hydroxyl radicals (OH) was demonstrated to be mediated by free radical trapping investigations, which were utilized to determine the active components of the process.

Effect of Tm3+ ion doping on the possibility of Bragg resonator inscription using an excimer laser

Effect of Tm3+ ion doping on the possibility of Bragg resonator inscription using an excimer laser

Oxidative coupling of methane and oxidative dehydrogenation of ethane reactions over La-based monoclinic layered perovskite and double perovskite

Herein, we partially doped the A-site or B-site cations of the monoclinic layered perovskite La2Ti2O7 with alkali metal ions (Na+ and K+) and alkaline earth metal ions Mg2+ to form double perovskites (NaLaTi2O6, KLaTi2O6, and LaTiMgO6) for the oxidative coupling of methane (OCM) and oxidative dehydrogenation of ethane (ODHE), demonstrating that the compatibility between the radii of the heterovalent doping ions and the radii of the host perovskite A-site and B-site cations is an important factor affecting their reaction performance. Doping with heterovalent ions changes the crystal symmetry and structure of the host perovskite La2Ti2O7, and when the radius of the doping ion is closer to that of the host A- or B-site ion, more oxygen vacancies can be generated and more chemisorbed oxygen species can form. The oxygen vacancies are closely related to the moderate basic sites, and the reactive oxygen species in OCM and ODHE are O2δ- and O2−. Doping with B-site cations is more beneficial for improving the reaction performance than doping with A-site cations. This is attributed to the covalent property of the B-O bond in perovskite, as doping with B-site cations can weaken the covalent bond, thereby facilitating the formation of oxygen vacancies. Moreover, the additional chemisorbed oxygen generated by oxygen vacancies resulting from high-temperature crystal phase transitions/lattice distortions in perovskite can further enhance reaction performance.

Cross-luminescence in BaF[formula omitted] crystals doped with M[formula omitted] and RE[formula omitted] ions: Hybrid density functional theory study

Radiation resistant inorganic materials emitting cross-luminescence are one of the most prospective candidates for new generation ultrafast detectors for medical tomography. Radiative transitions leading to cross-luminescence occur between valence and core states, and therefore calculations of the electronic structure of doped materials can explain ultrafast transitions and predict new cross-luminescent materials. In current work we demonstrate results of ab initio calculations of undoped and doped BaF2 by means of hybrid density functional theory. As a result of the work, the density of states (DOS) for nominally pure BaF2 and a whole series of BaF2 doped with various trivalent ions were obtained. The positions of the core energy levels of dopant ions lying between the Ba(5p) zone and the F(2s) zone, as well local geometries and formation energies were calculated. Our calculations show that the 5p states of impurity ions can be located below the 5p zone of barium by several eV. This opens up opportunities for transitions from the core 5p Ba zone to impurity 5p states, which might be involved in experimentally observed appearance of an ultrafast component in doped BaF2.

Sodium lanthanum boro-tellurite glasses with Sm3+ ion doping and gold nanoparticle embedding: A new glass matrix for solid state lighting devices

Herein, we have fabricated sodium lanthanum boro-tellurite glasses co-doped with Sm3+ and gold nanoparticles (AuNPs) using a melt-quenching process and studied their optical performance. An X-ray diffractometer (XRD), Raman spectroscopy, and high-resolution transmission electron microscopy (HR-TEM) were utilized to examine the sample's crystal structure and morphology. The spectral attributes of the obtained glass specimens have been investigated utilizing UV–vis–NIR absorbance and PL emission data. The fabricated glass specimens were in a pure amorphous form, as proven by the XRD observations. The occurrence of AuNP and its size growth in response to AuCl4 concentration have been corroborated by HR-TEM investigation. The surface plasmon resonance peak of AuNPs was detected between 520 and 600 nm. To ascertain the local structure and bonding surrounding Sm3+ ions, three phenomenological Judd-Ofelt (J-O) parameters (Ωt, where, t=2,4,6) were evaluated using optical absorption data. The PL data acquired at an excitation wavelength of 402 nm showed four emission curves. The maximum emission intensity was detected in 0.010 mol% of AuCl4 content. In addition to potential emission band intensity, glass specimens bearing AuNPs have been proven to exhibit higher radiative attributes including branching ratio (βR) and stimulated emission cross-section (σemi). The beneficial emission attributes of the AuNP-containing glasses suggest that they are suitable for the creation of photonic devices emanating radiation in the orange-red range.

The Electrocatalytic Performance of Rare Earth Ion Doped Co0.2Ni0.8-MOF-74 Catalyst for Nitrogen Reduction

The Electrocatalytic Performance of Rare Earth Ion Doped Co0.2Ni0.8-MOF-74 Catalyst for Nitrogen Reduction

Prompting CO2 Electroreduction to Ethanol by Iron Group Metal Ion Dopants Induced Multi‐sites at the Interface of SnSe/SnSe2 p–n Heterojunction

AbstractThe development of non‐copper‐based materials for CO2 electroreduction to ethanol with high selectivity at large current density is highly desirable, but still a great challenge. Herein, we report iron group metal ions of M2+ (M=Fe, Co, or Ni)‐doped amorphous/crystalline SnSe/SnSe2 nanorod/nanosheet hierarchical structures (a/c‐SnSe/SnSe2) for selective CO2 electroreduction to ethanol. Iron group metal ions doping induces multiple active sites at the interface of M2+‐doped SnSe/SnSe2 p‐n heterojunction, which strengthens *CO intermediate binding for further C−C coupling to eventual ethanol generation. As a representative, Fe9.0%‐a/c‐SnSe/SnSe2 exhibits an ethanol Faradaic efficiency of 62.7 % and a partial current density of 239.0 mA cm−2 at −0.6 V in a flow cell. Moreover, it can output an ethanol Faradaic efficiency of 63.5 % and a partial current density of 201.2 mA cm−2 with a full‐cell energy efficiency of 24.1 % at 3.0 V in a membrane electrode assembly (MEA) electrolyzer. This work provides insight into non‐Cu based catalyst design for stabilizing the key intermediates for selective ethanol production from CO2 electroreduction.

Prompting CO2 Electroreduction to Ethanol by Iron Group Metal Ion Dopants Induced Multi-sites at the Interface of SnSe/SnSe2 p-n Heterojunction.

The development of non-copper-based materials for CO2 electroreduction to ethanol with high selectivity at large current density is highly desirable, but still a great challenge. Herein, we report iron group metal ions of M2+ (M=Fe, Co, or Ni)-doped amorphous/crystalline SnSe/SnSe2 nanorod/nanosheet hierarchical structures (a/c-SnSe/SnSe2) for selective CO2 electroreduction to ethanol. Iron group metal ions doping induces multiple active sites at the interface of M2+-doped SnSe/SnSe2 p-n heterojunction, which strengthens *CO intermediate binding for further C-C coupling to eventual ethanol generation. As a representative, Fe9.0%-a/c-SnSe/SnSe2 exhibits an ethanol Faradaic efficiency of 62.7 % and a partial current density of 239.0 mA cm-2 at -0.6 V in a flow cell. Moreover, it can output an ethanol Faradaic efficiency of 63.5 % and a partial current density of 201.2 mA cm-2 with a full-cell energy efficiency of 24.1 % at 3.0 V in a membrane electrode assembly (MEA) electrolyzer. This work provides insight into non-Cu based catalyst design for stabilizing the key intermediates for selective ethanol production from CO2 electroreduction.

Improving the Electrochemical Performance of Garnet-Type Electrolytes through Ion Doping and Surface Treatment

Improving the Electrochemical Performance of Garnet-Type Electrolytes through Ion Doping and Surface Treatment

Tunable double emission of Sb3+/Mn2+ doping stabilized organic-inorganic hybrid zinc-based halides

Low-dimensional organic-inorganic hybrid metal halides (OIHMHs) have attracted much attention lately in contrast to all-inorganic metal halides because of their excellent photophysical properties and tunable emission wavelengths. Zn-based metal halides have the following advantages: simplicity of synthesis, wide bandgap, and excellent chemical stability. Therefore, they are well-suited as host materials for photoluminescence by cation ion doping. We have successfully synthesized intrinsically non-emissive 0D (PPZ)ZnCl4 [PPZ (1-phenylpiperazine) = C10H14N2], and by mono/co-doping with Mn2+ and Sb3+, interesting luminescence phenomena have been produced. Single-doped Mn2+ / Sb3+ shows distinctive green and single orange emission, respectively. However, the co-doped Mn2+ and Sb3+ appeared as dynamic double emission peaks at 530 nm and 670 nm. Therefore, the co-doped crystals showed luminescence from two different luminescence centers ([MnCl4]2- and [SbCl4]-). We used DFT to calculate the DOS (density of states) of co-doped crystals, which results in energy transfer between Mn2+ and Sb3+. All of the above samples showed high stability after being left for two months. In addition, two different luminescence centers can be produced by the adjustment of the excitation of the co-doped (PPZ)ZnCl4: Sb0.12Mn0.08 samples, which is a distinguishable and obvious photoluminescence phenomenon having great potential preparation of advanced anti-counterfeiting materials in the future.

Progress in the Application of LiMnPO4 Nanomaterials in Lithium-ion Battery Cathode

Lithium-ion batteries (LIBs) have become vital in today's energy storage systems, especially for electric cars and portable gadgets. High energy density, extended cycle life, and quick charging times are features of lithium batteries. Compared to conventional batteries, they are lightweight, ecologically benign, and have a low self-discharge rate. LiMnPO4 nanomaterials have garnered significant interest among various cathode materials due to their superior thermal stability, safety, and high operating voltage. The main topics of this paper are the structural characteristics, production techniques, and performance improvements of LiMnPO4 nanoparticles as LIBs cathodes. The basic operating principles of LIBs were covered in this article, with particular attention paid to the redox reactions occurring at the electrodes, the unique olivine structure of LiMnPO4, and how these factors affect electrochemical performance. The efficiency of many synthesis methods, such as spray pyrolysis, sol-gel, solid-state, hydrothermal, and solvothermal processes, in yielding superior LiMnPO4 nanoparticles is assessed. Additionally, surface modifications through ion doping and carbon coating are reviewed to highlight their roles in enhancing conductivity and stability. This article aims to provide ideas for developing high-performance LiMnPO4 cathode materials to affect LIBs' development positively. This article aims to provide ideas for developing high-performance LiMnPO4 cathode materials to influence LIBs' development positively.