Doping Elements Research Articles

Ultra‐high Capacity and Stable Dual‐ion Batteries with Fast Kinetics Enabled by HOF Supermolecules Derived 3D Nitrogen‐Oxygen Co‐doped Nanocarbon Anodes

AbstractThe low capacity, poor cycling life, and rapid self‐discharge hinder the development of carbonaceous dual‐ion batteries (DIBs). Conventional preparations of element doping amorphous carbons are cumbersome, complex, and difficult to control the doping element, content, and size. Here, a nitrogen‐oxygen co‐doped amorphous carbon nanomaterial (NDC) with unique 3D vortex‐layered amorphous structure and high doping content is ingeniously prepared via self‐assembly of hydrogen‐bonded organic framework precursors followed by one‐step pyrolysis, and then used for anodes of DIBs. By pairing with a commercial Nylon separator, a self‐supporting independent graphite cathode, and a high‐concentration electrolyte, the NDC‐based DIBs display an ultra‐high specific discharge capacity of up to 519 mAh g−1 at 1 C, low self‐discharge rate of 0.85% h−1, capacity retention of 98.8% after 1500 cycles, and fast kinetic dynamics. This study offers a novel approach to enable carbonaceous nanomaterials for energy‐dense and long‐cycling DIBs.

A ratiometric fluorescent sensor based on S-doped BCNO quantum dots and Au nanoclusters combined with 3D-printing portable device for the detection of malachite green.

Sulfur-doped BCNO quantum dots (S-BCNO QDs) emitting green fluorescence were prepared by elemental doping method. The ratiometric fluorescence probe with dual emissions was simply established by mixed S-BCNO QDs with gold nanoclusters (GSH-Au NCs). Because the emission spectrum of Au NCs (donor) at 615nm overlapped well with the ultraviolet absorption of malachite green (MG), fluorescence resonance energy transfer (FRET) can be achieved. When the concentration of MG increased, the fluorescence intensity (F495) of S-BCNO QDs decreased slowly, while the fluorescence intensity (F615) of Au NCs decreased sharply.The fluorescence intensity ratio of F615/F495 decreased with the increase of MG. By plotting the F615/F495 values against MG concentration, a sensitive and rapid detection of MG was possible with a wide detection range (0.1-50 µM) and a low detection limit of 10 nM. Due to the accompanying fluorescence color change from pink to blue-green, it can be used for visual detection. A three dimensional-printing device utilizing digital image colorimetry to capture color changes through the built-in camera, enables quantitative detection of MG with a good linearity between the values of red/green ratioand MG concentrations at the range 1-50 µM. This sensing platform had a range of advantages, including high cost-effectiveness, portability, ease of operation, and high sensitivity. Furthermore, the sensing platform was successfully applied tothe detection of MG in real water sample and fish samples, thereby verifying the reliability and effectiveness of this sensing platform in water quality monitoring and food safety.

Effect of laser energy density on microstructure and critical current of YGBCO and HGBCO films fabricated by PLD

Y0.5Gd0.5Ba2Cu3O7-σ (YGBCO) and Ho0.5Gd0.5Ba2Cu3O7-σ (HGBCO) targets with similar densities were prepared by solid-phase reaction. Pulsed laser deposition (PLD) technology was used to fabricate superconducting films with these targets. During the experiments in this paper, we varied the laser energy by adjusting the optical lens. The structure and texture of RE0.5Gd0.5Ba2Cu3O7-σ (REGBCO, where RE = Y, Ho) thin films were analyzed by X-ray diffraction (XRD). The surface morphology was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM), and the superconducting critical current was measured at 77 K using the standard four-probe method. The laser energy density and different doping elements can affect the properties of REGBCO films. This may be related to the ejection process of target particles and the size of rare earth atoms. Additionally, we prepared a 510-meter long second-generation high-temperature superconducting tape with the optimized parameters. The critical current of the tape is 350 A, and the current density is 3.9 × 106 A/cm2.

Study on optoelectronic properties of CuInSe2/CuInSSe films and PN junctions

CuInSe2 (CIS) is a semiconductor with a direct bandgap of about 1.04 eV. Its potential applications in the field of flexible thin-film solar cells are vast and promising. Improving cell performance through the sulfidation of the CIS absorber layer is a vital method. Furthermore, the bandgap can be adjusted through ideal element doping and interfacial state recombination can be decreased. In this study, the mixed source vacuum evaporation is used to prepare CIS, CuInS1.5Se0.5 and CuInS0.5Se1.5 films, followed by annealing under N2, S, and Se atmospheres. Subsequently, Mo/CIS/CdS PN junction and Mo/CuInSxSe2-x (x = 0.5 or 1.5)/CdS PN junctions are fabricated. The results demonstrate that Se-annealing of CIS films reduces hetero-phase formation, improves crystallization quality and yields high intensities of transmittance and reflectance. S-annealing of CISSe films results in enhanced intensities of transmittance and reflectance. The intensities of the primary XRD peaks of CuInS0.5Se1.5 film are greater than those of the CuInS1.5Se0.5 film. The morphologies of the CISSe films become flatter and smoother as annealing in S-atmosphere. The CuInS1.5Se0.5 film shows a higher photocurrent compared to the CuInS0.5Se1.5 film, suggesting that a greater proportion of S can enhance photo carrier concentration of CISSe films. Additionally, the carrier transport in S-annealed CuInS0.5Se1.5/CdS PN junction is predominantly governed by tunneling current mechanism, while carrier transports of other PN junctions are regulated by leakage current mechanism.

High-Repetition-Rate 2.3–2.7 µm Acousto-Optically Tuned Narrow-Line Laser System Comprising Two Master Oscillators and Power Amplifiers Based on Polycrystalline Cr2+:ZnSe with the 2.1 µm Ho3+:YAG Pulsed Pumping

High-average-power narrow-linewidth tunable solid-state lasers in the wavelength region between 2 and 3 μm are attractive light sources for many applications. This paper reports a narrow-linewidth widely tunable laser system based on the polycrystalline Cr2+:ZnSe elements pumped by repetitively pulsed 2.1 µm Ho3+:YAG laser operating at a pulse rate of tens of kilohertz. An advanced procedure of ZnSe element doping and surface improvement was applied to increase the laser-induced damage threshold, which resulted in an increase in the output power of the Cr2+:ZnSe laser system. The high-average-power laser system comprised double master oscillators and power amplifiers: Ho3+:YAG and Cr2+:ZnSe laser oscillators, and Ho3+:YAG and Cr2+:ZnSe power amplifiers. The output wavelength was widely tuned within 2.3–2.7 µm by means of an acousto-optical tunable filter inside a Cr2+:ZnSe master oscillator cavity. The narrow-linewidth operation at the pulse repetition rate of 20–40 kHz in a high-quality beam with an average output power of up to 9.7 W was demonstrated.

Inhibiting the Jahn-Teller Effect of Manganese Hexacyanoferrate via Ni and Cu Codoping for Advanced Sodium-Ion Batteries.

Manganese (Mn)-based Prussian blue analogs (PBAs) are of great interest as a prospective cathode material for sodium-ion batteries (SIBs) due to their high redox potential, easy synthesis, and low cost. However, the Jahn-Teller effect and low electrical conductivity of Mn-based PBA cause poor structure stability and unsatisfactory performance during the cycling. Herein, a novel nickel- and copper-codoped K2Mn[Fe(CN)6] cathode is developed via a simple coprecipitation strategy. The doping elements improve the electrical conductivity of Mn-based PBA by reducing the bandgap, as well as suppress the Jahn-Teller effect by stabilizing the framework, as verified by the density functional theory calculations. Simultaneously, the substitution of sodium with potassium in the lattice is beneficial for filling vacancies in the PBA framework, leading to higher average operating voltages and superior structural stability. As a result, the as-prepared Mn-based cathode exhibits excellent reversible capacity (116.0 mAh g-1 at 0.01 A g-1) and superior cycling stability (81.8% capacity retention over 500 cycles at 0.1 A g-1). This work provides a profitable doping strategy to inhibit the Jahn-Teller structural deformation for designing stable cathode material of SIBs.

Metal Doped Unconventional Phase IrNi Nanobranches: Tunable Electrochemical Nitrate Reduction Performance and Pollutants Upcycling.

Electrochemical nitrate reduction (NO3RR) provides a new option to abate nitrate contamination with a low carbon footprint. Restricted by competitive hydrogen evolution, achieving satisfied nitrate reduction performance in neutral media is still a challenge, especially for the regulation of this multielectron multiproton reaction. Herein, facile element doping is adopted to tune the catalytic behavior of IrNi alloy nanobranches with an unconventional hexagonal close-packed (hcp) phase toward NO3RR. In particular, the obtained hcp IrNiCu nanobranches favor the ammonia production and suppress byproduct formation in a neutral electrolyte indicated by in situ differential electrochemical mass spectrometry, with a high Faradaic efficiency (FE) of 85.6% and a large yield rate of 1253 μg cm-2 h-1 at -0.4 and -0.6 V (vs reversible hydrogen electrode (RHE)), respectively. In contrast, the resultant hcp IrNiCo nanobranches promote the formation of nitrite, with a peak FE of 33.1% at -0.1 V (vs RHE). Furthermore, a hybrid electrolysis cell consisting of NO3RR and formaldehyde oxidation is constructed, which are both catalyzed by hcp IrNiCu nanobranches. This electrolyzer exhibits lower overpotential and holds the potential to treat polluted air and wastewater simultaneously, shedding light on green chemical production based on contaminate degradation.

Mechanochemically Robust LiCoO2 with Ultrahigh Capacity and Prolonged Cyclability.

Pushing intercalation-type cathode materials to their theoretical capacity often suffers from fragile Li-deficient frameworks and severe lattice strain, leading to mechanical failure issues within the crystal structure and fast capacity fading. This is particularly pronounced in layered oxide cathodes because the intrinsic nature of their structures is susceptible to structural degradation with excessive Li extraction, which remains unsolved yet despite attempts involving elemental doping and surface coating strategies. Herein, a mechanochemical strengthening strategy is developed through a gradient disordering structure to address these challenges and push the LiCoO2 (LCO) layered cathode approaching the capacity limit (256mAhg-1, up to 93% of Li utilization). This innovative approach also demonstrates exceptional cyclability and rate capability, as validated in practical Ah-level pouch full cells, surpassing the current performance benchmarks. Comprehensive characterizations with multiscale X-ray, electron diffraction, and imaging techniques unveil that the gradient disordering structure notably diminishes the anisotropic lattice strain and exhibits high fatigue resistance, even under extreme delithiation states and harsh operating voltages. Consequently, this designed LCO cathode impedes the growth and propagation of particle cracks, and mitigates irreversible phase transitions. This work sheds light on promising directions toward next-generation high-energy-density battery materials through structural chemistry design.

Entropy-assisted low-electrical-conductivity pyrochlore for capacitive energy storage

Capacitors with high energy storage performances are highly desired for the miniaturization, lightweight, and integration of high-end pulse systems. However, the trade-off between dielectric constant and breakdown strength restricts further performance optimization. To improve energy storage properties, a new tactic with rising attention, the high-entropy concept, has been demonstrated to suppress leakage current and enlarge the breakdown strength. However, the mechanisms connecting the insulation properties and entropy are still unclear. Herein, we successfully fabricated a series of entropy-modulated Cd2Nb2O7-based pyrochlore ceramics via the doping of multiple elements, and high-entropy pure pyrochlore was obtained due to the entropy-stabilization effect. Our results revealed that the insulation properties are distinctly enhanced via the enlarged carrier transport barriers and reduced carrier concentration, which should be attributed to entropy-induced large lattice distortion, grain-refining, and fewer defects. The optimized insulation properties significantly enhance breakdown strength from 148 kV cm−1 to 457 kV cm−1. A high energy density of 2.29 J cm−3 with a high energy efficiency of 88% is thus achieved in the high-entropy ceramic, which is 150% higher than the pristine material. This work indicates the effectiveness of high-entropy design in the improvement of energy storage performance, which could be applied to other insulation-related functionalities.

Exploring high-valence element doping in LLZO electrolytes: Effects on phase transition and lithium-ion conductivity

The increasing popularity of electric vehicles and the emergence of 5G technology have created a demand for high-energy-density and safe batteries. Among various solid-state electrolytes, crystalline Li7La3Zr2O12 (c-LLZO) has garnered significant attention due to its exceptional properties. Researchers have explored doping in LLZO to modulate its phase transition and enhance lithium-ion conductivity. However, the mechanism by which doping induces a phase change and affects lithium-ion conductivity is currently unclear. In this study, we investigated LLZO doping and discovered that high-valence-element doping introduces vacancies, destabilizing the tetragonal phase and promoting the formation of the stable cubic phase. Moreover, we found that the introduction of lithium-ion vacancies significantly enhances lithium-ion conductivity. Nevertheless, doping also has adverse effects. Ga and Al dopants occupy the crucial Li24d sites, impeding lithium-ion diffusion and resulting in the closure of diffusion channels. Additionally, doping reduces the effective vacancy concentration within the structure, further restricting lithium-ion conductivity. In summary, our work elucidates the mechanism behind the influence of dopants on lithium-ion diffusion in LLZO.

Organic Molecule and Inorganic Salt Synergistic‐Modified SnO2 for Efficient Perovskite Solar Cells

Element doping and interface modification strategy are effective methods to regulate the electrical properties of SnO2 electron transport material, SnO2/perovskite (PVK) interface, and PVK crystal growth. Herein, rubidium fluoride (RbF) is introduced into SnO2 colloidal dispersion, and then an ultra‐thin layer of 4‐carboxy‐3‐fluorobenzoboric acid (FBCA) is applied to the SnO2 layer surface. This synergistic modification strategy can improve the electrical conductivity of the electron transport layer, increase the chemical connection of the buried interface, improve the crystallization and grain growth of PVK, and thus promote the performance and stability of devices. The results show that the PVK solar cells (PSCs) with the synergistic‐modified SnO2 electron transport material (M‐SnO2) obtain an optimum power conversion efficiency of 21.92% and the unencapsulated PSCs sustain 91% and 87% of the original value, which stored in a nitrogen atmosphere and ambient atmosphere (25 ± 5 °C, 30–50% relative humidity) more than 1000 h, respectively.

Initial stage oxidation corrosion of commercial ferritic stainless steels with different Cr contents at 650 °C for solid oxide fuel cells

Selecting adequate ferritic stainless steel (FSS) with a high corrosion resistance and a low cost is critical for solid oxide fuel cells (SOFCs) operating at intermediate temperature. In this study, the corrosion behaviors of four commercial FSSs involving TS430, TY441, YG442, and TY445 with a Cr content ranging from 16.18 wt.% to 21.73 wt.% are investigated at 650 °C. The oxidation mass gains, microstructures of surface oxide scale, and electrical conductivities are measured. The effects of grain size as well as doped elements are estimated together with the Cr volatilization. Flaky Cr2O3 particles are formed on TS430 and TY441 dominated by the outward migration of Cr3+. In comparison, a thin and dense layer of chromia is observed on YG442 and TY445. A high Cr content and a uniformly distributed grain size are conducive to the formation of a thin and dense chromia scale on the FSS surface during the initial oxidation process. On the other hand, the addition of Nb, Ti, and Mo weakens the outward diffusion of Cr3+ and reduces the particle size of chromia. After oxidation at 650 °C for 120 h, scattered (Mn, Cr)3O4 spinel particles occur on TS430, YG442, and TY445. TY445 and YG442 exhibit a higher conductivity although all the results of area specific resistance (ASR) are less than 6 mΩ·cm2. Meanwhile, the effect of Cr volatilization is enlarged on the estimation of mass gain at 650 °C compared with even higher temperatures.

N, P-doped NiCo2S4 nanospheres with excellent hydrophilicity for efficient oxygen evolution reaction

The rational design of a robust hydrophilic electrocatalyst is essential for enhancing its oxygen evolution reaction(OER). In this work, a nanosphere catalyst (NiCo2S4) composed of 2D-nanosheets was prepared. Interestingly, The hierarchically porous hydrangea-like N,P-NiCo2S4 structure was formed through the doping of nonmetal elements N and P. With the introduction of N and P, the electronic structure of Ni and Co can be optimized and the charge transfer resistance of NiCo2S4 can be reduced, thus improving the kinetics of OER. More importantly, N and P doping increased the hydrophilicity of NiCo2S4, which may have accelerated the surface reconstruction of NiCo2S4, resulting in the generation of truly active sites. Overall, this work not only optimised the electronic structure of NiCo2S4, but also improved its hydrophilicity through the synergistic interaction between the nonmetal elements N and P, which provided ideas for the development of advanced non-noble metal electrocatalysts.

Engineered K-doped ZnO/borneol based hydrogel composite material for led-based photocatalytic degradation of methylene blue and evaluation of antimicrobial activity

The significant improvement of decolorization and disinfection technologies has been a hotspot in wastewater reutilization. In this study, we realized a novel construction of K-doped nano-ZnO and borneol based hydrogel composite material (K-ZnO/B-hydrogel) by low-temperature in situ sol–gel growth. The techniques such as fourier transform infrared (FTIR), X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS) were applied to recognize the synthesized hydrogel. The results revealed that K-doped ZnO nanoparticles had been uniformly decorated onto the B-hydrogel. Ultraviolet-visible (UV–vis) absorption spectra showed that impurity doping of potassium element into ZnO could reduce the band gap, improving the visible light absorption efficiency. Under LED illumination, the photodegrading rate of K-ZnO/B-hydrogel was approximately 2.3 times greater than that of K-ZnO/B-hydrogel on methylene blue (MB) removal. Remarkably, aside from CO2 and H2O, no by-products were generated during the photodegradation process. In addition, the antimicrobial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) of K-ZnO/B-hydrogel achieved up to 99.9%, which were at least 1.5 times higher than K-ZnO/B-hydrogel. This composite will push ahead with a closed-loop wastewater treatment system for dye and pathogenic microorganism disposal, which combines the excellent adsorption ability of hydrogel and the outstanding photocatalytic ability of ZnO nanoparticles with easy sample handling and separation, and help to eliminate secondary pollution.

The influence mechanism of high-valence rare earth element doping on the thermoelectric properties of ZnO

The influence mechanism of high-valence rare earth element doping on the thermoelectric properties of ZnO

Boron-manganese-nitrogen co-doped three-dimensional porous carbon realizes superior capacitive lithium-ion storage

Three-dimensional (3D) porous carbon has sufficient specific surface area and anchor positioning points. The pore structure facilitates uniform charge distribution, and buffers volume changes during stripping. However, single carbon materials have limited theoretical capacity and short cycle life. Here, 3D porous carbon material BCN/Mn-6 (B,N and Mn co-doped porous carbon with 6 mmol Mn content) co-doped with manganese, boron and nitrogen was synthesized by heat treatment. Affective modulation of the material structure and surface functional groups was achieved by adjusting the amount of manganese doping. The metal element doping can promote the diffusion of lithium ions, and the formed vacancies and defects can be used as lithium storage sites. Nitrogen doping can improve the dispersion and stability of metals and oxides, and regulate the redox capacity. Co-doping of metals and heteroatoms synergistically improves electrical conductivity. Thus, BCN/Mn-6 exhibits excellent cycling stability (99.60 % Coulombic efficiency after 300 cycles) and specific capacity (779.9 mAh/g), and shows capacity rise. This study provides a new direction for the preparation of carbon-based electrode materials doped with heteroatoms and the study of capacitive energy storage mechanisms.

Spectroscopic Investigations of Complex Electronic Interactions by Elemental Doping and Material Compositing of Cobalt Oxide for Enhanced Oxygen Evolution Reaction Activity

AbstractDoping and compositing are two universal design strategies used to engineer the electronic state of a material and mitigate its disadvantages. These two strategies are extensively applied to design efficient electrocatalysts for water splitting. Using cobalt oxide (CoO) as a model catalyst, it is proven that the oxygen evolution reaction (OER) performance can be progressively improved, first by Fe‐doping to form Fe‐CoO solid solution, and further by the addition of CeO2 to produce a Fe‐CoO/CeO2 composite. X‐ray absorption spectroscopy (XAS) reveals that distinct electronic interactions are induced by the processes of doping and compositing. Fe‐doping of CoO can break down the structural symmetry, changing the electronic structure of both Co and O species at the surface and decreasing the flat‐band potential (Vfb). In comparison, subsequent compositing of Fe‐CoO with CeO2 induces negligible electronic changes in the Fe‐CoO (as seen in ex situ characterizations), but significantly modifies the oxidative transformations of both Co and Fe under OER conditions. The spectroscopic investigations reveal that Fe‐doping and CeO2 compositing play different roles in modifying the electronic properties of CoO in its pristine state and during OER catalysis, in return, providing useful guidance for the design of more efficient electrocatalysts using these two strategies.

Concentration effects in multicomponent metallic solid solutions

In the equiatomic approximation, the dependence of the lattice FCC parameter and the Debye temperature from the atomic fate x of the doping element, which is alternately represented by all elements of a multicomponent solid solution, including high-entropy alloys were obtained. The calculations were carried out on the example of a five-component (based on Cu, Ni, Co, Fe, and Al) or six-component (based on Cu, Ni, Co, Fe, and Cr, Ti) metal systems. It was found that by varying x within x = (0 - 0.3), it is possible to obtain a change in the lattice FCC parameter from 0 to 0.03 nm and the Debye temperatures from 0 to 80 K. The proposed new characteristics are integral and differential concentration coefficients, the magnitude and sign of which can predict concentration dependences for the lattice parameter and the Debye temperature.

Enhancing the thermoelectric and mechanical properties of Cu3SbSe4-based materials by defect engineering and covalent bonds reinforcement

Here, a typical microwave hydrothermal-assisted synthesis method is utilized to fabricate Co/Sn co-doped Cu3SbSe4 materials. Experimental results demonstrate that the formation of a nanoscale Co9Se8 phase occurs when the solid solubility of Co is exceeded. This phase effectively enhances phonon scattering at the grain boundary's high-density dislocation region, leading to a significant reduction in lattice thermal conductivity. Simultaneously, the interface between Co9Se8 and Cu3SbSe4 exhibits an energy filtering effect, resulting in an improved Seebeck coefficient. The maximum zT value of 0.62 is achieved in the Cu3Sb0.96Co0.04Se4 sample. To further regulate the carrier concentration, Sn atoms are introduced, leading to peak power factor and zT values of 865.98 μW·m−1·K−2 and 0.72, respectively. The incorporation of Co and Sn doping contributes to the enhancement of mechanical properties by reinforcing covalent bonds. Mechanical property testing of the materials indicates an improvement in mechanical performance upon doping with Co and Sn. This study provides valuable insights into the in-situ introduction of a second phase through element doping, thereby enhancing the comprehensive thermoelectric properties of Cu3SbSe4-based materials. Moreover, it establishes an experimental foundation for subsequent investigations into the materials' mechanical properties.

A Universal Strategy to Enhance Circularly Polarized Luminescence Brightness in Chiral Perovskites

AbstractChiral perovskites are considered as promising candidates for circularly polarized luminescence (CPL) light source, by attracting the broader scientific community for their applications in chiral optoelectronics and spintronics. However, it is still a great challenge to achieve both substantial photoluminescence asymmetry (gCPL) and high photoluminescence quantum yield (PLQY) simultaneously for high CPL brightness due to the limitations associated with magnetic transition dipole moments. Herein, this problem is overcome and achieve both large gCPL of 1.6×10−2 and PLQY of 56% in chiral perovskite through the magnetic element doping strategy. The substitution of Pb2+ ion with smaller magnetic Mn2+ ions shrinks the crystal lattice around [MnBr6]4− octahedra, amplifying the asymmetric distortion surrounding the Mn2+ ions. Moreover, the transition associated with Mn2+ ions can harvest the photoexcitation energy in chiral perovskites, and its spin‐flipping characteristics enable highly efficient CPL from the d–d transition on Mn2+ energy levels. Furthermore, this magnetic element doping strategy is proven to be a universal tactic for enhancing CPL brightness as confirmed in a series of 1D‐ or 2D‐chiral perovskites with various chiral ligands or halogens. The findings provide an in‐depth understanding of the structure‐property relationship in chiral perovskites toward chiral optoelectronic and spintronic applications.