Doping Elements Research Articles

Optoelectronic Property Exploration in SnS2 Monolayer and Homojunctions with Non-metallic Element (B, C, N) Doping: A First-Principles Investigation

Optoelectronic Property Exploration in SnS2 Monolayer and Homojunctions with Non-metallic Element (B, C, N) Doping: A First-Principles Investigation

Optical property dataset of inorganic phosphor

Developing inorganic phosphor with desired properties for light-emitting diode application has traditionally relied on time-consuming and labor-intensive material development processes. Moreover, the results of material development research depend significantly on individual researchers’ intuition and experience. Thus, to improve the efficiency and reliability of materials discovery, machine learning has been widely applied to various materials science applications in recent years. However, the prediction capabilities of machine learning methods fundamentally depend on the quality of the training datasets. In this work, we constructed a high-quality and reliable dataset that contains experimentally validated inorganic phosphors and their optical properties, sourced from the literature on inorganic phosphors. Our dataset includes 3952 combinations of 21 dopant elements in 2238 host materials from 553 articles. The dataset provides material information, optical properties, measurement conditions for inorganic phosphors, and meta-information. Among the preliminary machine learning results, the essential properties of inorganic phosphors, such as maximum Photoluminescence (PL) emission wavelength and PL decay time, show overall satisfactory prediction performance with coefficient of determination (R2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R^2$$\\end{document}) scores of 0.7 or more. We also confirmed that the measurement conditions significantly improved prediction performance.

Quantitative analysis of element substitution in mixed-vanadate LuxGd1-xVO4 single crystals at the atomic scale

In mixed crystals, two or more elements exhibit comparable properties and can be substituted freely. As a special type of “substitutional doping,” the properties of materials can be adjusted by altering the doping ratio of elements. Mixed-vanadate crystal LuxGd1-xVO4 is a promising laser host material with excellent chemical stability, mechanical property and thermal conductivity. The substitutional doping ratio of the two rare-earth elements determines the value of x. The thermal, optical, and laser properties of the material vary with x. However, the two types of atoms showing little difference in the same location in mixed crystals form substitutional solid solutions with alike atomic radii as well as electronic structures. Therefore, distinguishing comparable elements in mixed crystals at the atomic scale and quantitatively analyzing the doping ratio in mixed crystals are challenging. In this study, combining high-angle annular dark field (HAADF) and electron energy-loss spectroscopy (EELS), we accurately characterize the atomic structure of mixed-vanadate single crystal LuxGd1-xVO4 along the [111] orientation as well as the distribution of two rare-earth elements at the atomic scale. The ratio of Lu and Gd and the doping rules in the crystals are quantitatively analyzed. In addition, combined with the energy dispersive X-ray spectroscopy (EDS) results of the [100] crystal orientation, a uniform random distribution of Lu and Gd in the LuxGd1-xVO4 crystal is confirmed. This study provides a new means of understanding mixed-crystal structures and solves the problem of quantitative analysis of elemental doping in materials at the atomic scale, thus laying the foundation for exploring the relationships among composition, structure, and function in materials.

Ultrahigh peroxidase-like catalytic performance of Cu–N4 and Cu–N4S active sites-containing reduced graphene oxide for sensitive electrochemical biosensing

Carbon-based nanozymes possessing peroxidase-like activity have attracted significant interest because of their potential to replace native peroxidases in biotechnology. Although various carbon-based nanozymes have been developed, their relatively low catalytic efficiency needs to be overcome to realize their practical utilization. Here, inspired by the elemental uniqueness of Cu and the doped elements N and S, as well as the active site structure of Cu-centered oxidoreductases, we developed a new carbon-based peroxidase-mimicking nanozyme, single-atom Cu-centered N- and S-codoped reduced graphene oxide (Cu-NS-rGO), which preserved many Cu–N4 and Cu–N4S active sites and showed dramatically high peroxidase-like activity without any oxidase-like activity, yielding up to 2500-fold higher catalytic efficiency (kcat/Km) than that of pristine rGO. The high catalytic activity of Cu-NS-rGO might be attributed to the acceleration of electron transfer from Cu single atom as well as synergistic effects from both Cu–N4 and Cu–N4S active sites, which was theoretically confirmed by Gibbs free energy calculations using density functional theory. The prepared Cu-NS-rGO was then used to construct an electrochemical bioassay system for detecting choline and acetylcholine by coupling with the corresponding oxidases. Using this system, both target molecules were selectively determined with high sensitivity that was sufficient to clinically determine their levels in physiological fluids. Overall, this study will facilitate the development of nanocarbon-based nanozymes and their electrochemical biosensing applications, which can be extended to the development of miniaturized devices in point-of-care testing environments.

Tuning Thermal Stability and Power Consumption of Sb2Te3 Phase Change Memory with Metallic Elements

AbstractPhase change materials have issues in the automotive industry and in‐memory computing due to their limited thermal stability and high power consumption. Consequently, numerous studies are conducted to enhance the performance of these materials. Uncertainty persists regarding the effects and mechanisms of various doping on the parent material. In this study, four metallic doping elements are selected, and their effects on Sb2Te3 are meticulously analyzed through experiments and ab initio calculations. The thermal stability of Sb2Te3 has been somewhat enhanced by doping these four elements, with Ta doping having the most impact. According to the ab initio molecular dynamics, this improvement results from the tetrahedral centered In and the increased coordination numbers of Ta, Ti, and Sc. Sc located at the center of the octahedron can accelerate the crystallization process. Ta, in particular, exerts the greatest influence on the migration rates of Sb and Te, resulting in the slowest grain growth rate. Simultaneously, it maximizes the delay in the transition from the cubic phase to the hexagonal phase. These features are beneficial for reducing power consumption. The elucidation of the distinct effects of doping elements sets the stage for phase change memory to adapt to various application scenarios.

Enhanced the SRB corrosion resistance of 316L stainless steel via adjusting the addition of Cu and Ce elements

316L stainless steel (SS) is the key raw material for the preparation of high-performance oil and gas pipelines, but even 316L with excellent properties will be attacked by sulfate-reducing bacteria (SRB) corrosion. Excellent antibacterial effects have been obtained in other SS systems by doping antibacterial elements. However, the current research on the preparation of antibacterial 316L SS is not comprehensive, and the quantitative analysis of the antibacterial mechanism and doping elements is still unclear. In this paper, the SS with Cu and Ce added were prepared by vacuum induction melting. Then the homogenization treatment combined with hot rolling was used to improve the structure segregation and mechanical properties. Further, the weight loss tests and electrochemical tests were conducted to evaluate the corrosion resistance of SS, the corrosion products and morphology were analysed, and the deformation structure was characterized to clarify the corrosion mechanism of the modified SS and quantify the doping elements. The results indicate that the microstructure after homogenization is mainly austenite, and with the increase of Ce content, the Ce-rich phase segregates. The inhibitory effect of Cu on SRB can be explained by the destructive effect of Cu ions on cell membranes. On this basis, adding a low content of Ce element can increase the permeability of the SRB cell wall and further enhance the attack effect of Cu ions on the cell membrane. The corrosion behavior of alloys shows the deformation structure dependence, with crystal defects and segregation increasing the corrosion rate. The optimal addition amount of Ce is 0.18 wt%, and the strength and elongation of SS are 511.18 MPa and 108.2%, respectively.

Intralayer ordered structure engineering for long-life Mn-based potassium-ion battery cathodes

Mn-based layered oxides have become one of the most promising cathode materials in potassium-ion batteries (PIBs) due to their high theoretical specific capacity. Nonetheless, the Jahn-Teller effect of Mn3+ leads to lattice distortion and a high K+ migration barrier, resulting in structural instability during the charge/discharge processes. To effectively overcome these problems, this work provides a method to change electronic energy levels to suppress the Jahn-Teller effect through the synergistic regulation of multiple specific element doping. The X-ray diffraction pattern of K0.4Mn0.7Ti0.1Ni0.1Cu0.1O2 shows its P3-type structure. The electrochemical test results demonstrate that K0.4Mn0.7Ti0.1Ni0.1Cu0.1O2 exhibits superior rate capacity, higher discharge specific capacity, and significant cycling stability (with a capacity retention rate of 80 % after 860 charge/discharge cycles). The in-situ X-ray diffraction pattern demonstrates the high reversibility of the electrochemical process of K+ insertion/extraction. First-principles calculations have confirmed that the electronic energy levels of K0.4Mn0.7Ti0.1Ni0.1Cu0.1O2 have better dispersion, the K+ migration channel has been effectively optimized, and the K+ migration barrier has been reduced. This study provides a significant and effective reference for the design of advanced PIBs with high performance.

Advancements in Transparent Conductive Oxides for Photoelectrochemical Applications.

Photoelectrochemical cells (PECs) are an important technology for converting solar energy, which has experienced rapid development in recent decades. Transparent conductive oxides (TCOs) are also gaining increasing attention due to their crucial role in PEC reactions. This review comprehensively delves into the significance of TCO materials in PEC devices. Starting from an in-depth analysis of various TCO materials, this review discusses the properties, fabrication techniques, and challenges associated with these TCO materials. Next, we highlight several cost-effective, simple, and environmentally friendly methods, such as element doping, plasma treatment, hot isostatic pressing, and carbon nanotube modification, to enhance the transparency and conductivity of TCO materials. Despite significant progress in the development of TCO materials for PEC applications, we at last point out that the future research should focus on enhancing transparency and conductivity, formulating advanced theories to understand structure-property relationships, and integrating multiple modification strategies to further improve the performance of TCO materials in PEC devices.

Understanding the effect of foreign atoms occupation on the metamagnetic behaviors in MnCoSi-based alloys: taking Pt-doping as an example

Present research on TiNiSi-type MnCoSi-based alloys focuses on finding a suitable doping element to effectively reduce the critical magnetic field (μ 0 H cri) required to induce a metamagnetic transition. This paper provides a guide to achieve this goal through an experimental investigation of Mn1−x Pt x CoSi and MnCo1−x Pt x Si alloys. In Mn1−x Pt x CoSi, as x increases, μ 0 H cri at room temperature decreases, while in MnCo1−x Pt x Si, it increases. This phenomenon can be attributed to the fact that larger Pt atoms prefer Co sites over Mn sites, as predicted by our density-functional theory. Consequently, in Mn1−x Pt x CoSi, larger Co atoms are extruded into the Mn atoms chain, increasing the nearest Mn–Mn distance and resulting in a reduced μ 0 H cri. This finding suggests that transition-metal atoms with more valence electrons preferably occupy the Co site, while those with fewer valence electrons preferably occupy the Mn site. Adhering to this rule, one can easily obtain a low μ 0 H cri and large magnetostrain under a low magnetic field by selecting a suitable foreign element and chemical formula, as demonstrated by the Mn1−x Pt x CoSi alloy.

Cr dopants and S vacancies in ZnS to trigger efficient photocatalytic H2 evolution and CO2 reduction

Driven by endless solar energy, photocatalytic H2 evolution from water splitting and CO2 conversion to hydrocarbon fuels over semiconductor photocatalysts are of great potential to simultaneously settle the greenhouse effect and energy shortage. Herein, Cr-doped zinc sulfide (ZnS) with accompanying sulphur vacancies (Vs) photocatalytic materials is developed by a facile hydrothermal method. The Cr dopants centralize photoinduced holes and Vs trap electrons, forming a synergistic effect for accelerating charge separation and transfer. The reaction energy barrier for both H2 evolution and CO2 reduction has been optimized. Therefore, in the absence of a cocatalyst, the optimal catalyst (Zn0.94Cr0.06S) achieves an outstanding H2 evolution activity of 20.3 mmol g−1 h−1, which is approximately 2.9 times higher than 6.9 mmol g−1 h−1 for pristine ZnS. In addition, in the gas-solid reaction system without co-catalysts or sacrificial agents, the Zn0.94Cr0.06S exhibits a considerable CO evolution rate of 19.56 μmol g−1 h−1, about 10.1 times higher than ZnS (1.94 μmol g−1 h−1). Both the performances for H2 evolution and CO2 reduction of Zn0.94Cr0.06S outperform most of the previously reported photocatalysts. Particularly, the Zn0.94Cr0.06S possesses superior stability, the photoactivity of which exhibits no noticeable deactivation after six cycles’ reactions. This work may shed light on the rational design and fabrication of highly efficient materials via combining individual element doping and defect engineering.

Effect of in-situ Zr doping on the crystallization behavior and electrochemical properties of cobalt-free layered LiNi0.8Mn0.2O2 cathode materials

Elemental doping is an effective strategy to overcome the degradation of the rate performance of cobalt-free layered cathode materials, which is attributable to the absence of cobalt. This study focuses on the implementation of a modified doping strategy, which entails in-situ coprecipitation to introduce 0.3 mol% Zr4+ as a dopant to these cathode materials. This approach enabled us to confirm that in-situ Zr4+ doping significantly impacted the crystallization behavior and electrochemical properties of these materials and this effect is not negligible. In particular, in-situ Zr4+ doping increased the crystallization temperature of the materials and broadened the spacing between the lithium layers while maintaining the original crystal configuration. The doped sample had the best cycling stability at the crystallization temperature of 800 °C (capacity retention of 80.03% after 200 cycles at the 1 C rate) and rate performance (discharge specific capacity of up to 161.6 mAh g−1 at the 5 C rate), whereas the original (undoped) sample delivered the best electrochemical performance at 780 °C (capacity retention of 74.29% after 200 cycles at the 1 C rate and discharge capacity at the 5 C rate of 154.57 mAh g−1).

Facile green synthesis of novel tantalum doped tungsten trioxide for photocatalytic degradation: Correlation with COMSOL simulation

The facilegreen synthesis techniqueis becoming more and more important, and it has been proposed as a potential substitute for chemical techniques. The current study describes a low-cost, environmentally friendly method for producing tungsten trioxide (WO3) and tantalum (Ta) doped WO3nanoparticles that uses 15 % (w/v) Azadirachta indica (Neem) leaf extract and different concentrations of Ta dopant (1 to 5 %) due to its well-matched ionic radius with WO3. Various techniques FESEM, TEM, EDX, BET, UV–Vis and PL, XRD, and FTIR were used to illustrate the morphological, elemental, optical, structural, and vibrational analysis of the synthesized nanoparticles respectively. Interestingly, the band gap was significantly reduced to 1.88 eV by the addition of a dopant element. For 3 % Ta/WO3, the average particle size was also reduced to 31.6 nm. The synthesized WO3nanoparticles employed in the current study have been used for photocatalytic activitypurposes. Methylene blue (MB), one of the principal water pollutants, was degraded more quickly by the synthesized Ta/WO3nanoparticles when exposed to UV radiation. Among them, 3 % Ta/WO3 gives significantly higher photodegradation 89 % attributed to the Burstein-Moss effect. The significant output of optimized nano-photocatalyst has been observed from the trapping experiment and reusability test. Furthermore, Zeta potential and TOC analysis have been taken to check the stability and mineralization performance. Additionally, the results of the simulation that was carried out using the finite element analysis approach in the RF module of COMSOL Multiphysics 5.3a are quite similar to the experimental findings. This simulation method made it easier for readers to understand the numerous aspects of the photocatalytic process that has been discussed here.

Deep Ultraviolet Light Emitting Diode Based on Aluminum Gallium Nitride

AlGaN-based deep ultraviolet LED has gradually attracted people's attention, because it can be used in sterilization, secret communication and other fields. According to the research report of nearly twenty years, there are still many shortcomings in the external quantum efficiency, internal quantum efficiency and light extraction efficiency of AlGaN-based deep ultraviolet LED. For this reason, researchers have made many efforts at the chip level, including epitaxial and doping technology. In recent years, more and more researchers have studied packaging technology with low light efficiency caused by Fresnel and total reflection. In epitaxial technology, this paper mainly introduces the material selection of substrate and the use of buffer layer. In this paper, the most commonly used substrate selection and the existing problems and solutions of substrates are summarized. The current process of buffer layer is also introduced. On the doping level, the present situation and development of N-type doping and P-type doping are introduced respectively. The use of the latest doping elements is introduced in this paper. Packaging technology explains the choice between organic materials and inorganic materials, and how the packaging structure can avoid the reflection loss of light to the maximum extent. Finally, the article predicts the future development direction.

Recent Advances of CeO2-Based Composite Materials for Photocatalytic Applications.

Photocatalysis has the advantages of practical, sustainable and environmental protection, so it plays a significant role in energy transformation and environmental utilization. CeO2 has attracted widespread attention for its unique 4 f electrons, rich defect structures, high oxygen storage capacity and great chemical stability. In this paper, we review the structure of CeO2 and the common methods for the preparation of CeO2-based composites in the first part. In particular, we highlight the co-precipitation method, template method, and sol-gel method methods. Then, in the second part, we introduce the application of CeO2-based composites in photocatalysis, including photocatalytic CO2 reduction, hydrogen production, degradation, selective organic reaction, and photocatalytic nitrogen fixation. In addition, we discuss several modification techniques to improve the photocatalytic performance of CeO2-based composites, such as elemental doping, defect engineering, constructing heterojunction and morphology regulation. Finally, the challenges faced by CeO2-based composites are analyzed and their development prospects are prospected. This review provides a systematic summary of the recent advance of CeO2-based composites in the field of photocatalysis, which can provide useful references for the rational design of efficient CeO2-based composite photocatalysts for sustainable development.

Dipole increase synergistic frustrated Lewis pairs induced by Sn dopant boosts ultrathin layered bismuth oxychloride for CO2 photoreduction

Photocatalytic conversion of CO2 into valued chemicals is limited by the CO2 adsorption and activation capability on catalyst surface. In this work, Sn element was successfully doped in ultrathin BiOCl with oxygen vacancies. The dipole moment of catalyst efficient increased due to the Sn doping, leading to a stronger internal electric field. In addition, the surface frustrated Lewis pairs were simultaneously constructed near the oxygen vacancies due to Sn dopant. The formed region of frustrated Lewis pairs-oxygen vacancies as active sites enable an improved CO2 adsorption, and the enhanced internal electric field intensity promoted the charge carrier separation and transfer, leading to the enhanced CO2 reduction performances. This work provides light on enhancing internal electric field by increasing dipole moment and presents feasible tunability of catalytic active sites at atom-scale, providing fundamental insights for understanding of mechanism of element doping in catalyst for improving CO2 photoreduction performance.

Understanding Advanced Transition Metal-Based Two Electron Oxygen Reduction Electrocatalysts from the Perspective of Phase Engineering.

Non-noble transition metal (TM)-based compounds have recently become a focal point of extensive research interest as electrocatalysts for the two electron oxygen reduction (2e- ORR) process. To efficiently drive this reaction, these TM-based electrocatalysts must bear unique physiochemical properties, which are strongly dependent on their phase structures. Consequently, adopting engineering strategies toward the phase structure has emerged as a cutting-edge scientific pursuit, crucial for achieving high activity, selectivity, and stability in the electrocatalytic process. This comprehensive review addresses the intricate field of phase engineering applied to non-noble TM-based compounds for 2e- ORR. First, the connotation of phase engineering and fundamental concepts related to oxygen reduction kinetics and thermodynamics are succinctly elucidated. Subsequently, the focus shifts to a detailed discussion of various phase engineering approaches, including elemental doping, defect creation, heterostructure construction, coordination tuning, crystalline design, and polymorphic transformation to boost or revive the 2e- ORR performance (selectivity, activity, and stability) of TM-based catalysts, accompanied by an insightful exploration of the phase-performance correlation. Finally, the review proposes fresh perspectives on the current challenges and opportunities in this burgeoning field, together with several critical research directions for the future development of non-noble TM-based electrocatalysts.

Sulfur vacancies and group VB metal atoms doping to synergistically optimize hydrogen evolution of MoS2 nanosheets

Molybdenum disulfide (MoS2) based materials exhibit promising potential for hydrogen evolution reaction (HER) performance and stability. Nevertheless, they face key challenges in electrochemical water splitting application as a result of their inert basal planes and limited active sites. On this basis, we attempt to systematically explore the effects of doping group VB metals and introducing sulfur (S) vacancies on improving the inherent conductivity and active sites of MoS2. The experimental consequences show that the catalytic activity of MoS2 doped with group VB metal elements and S-vacancies is significantly different from that of the pure MoS2 samples. In particular, the Nb-doped MoS2 catalyst has better performance than the pure MoS2. Additionally, density functional theory computations further confirm that the synergistic effects of group VB elements and S vacancies enhance the adsorption capacity of hydrogen atoms, resulting in boosting HER performance of the catalysts. The doping of group VB elements can optimize and improve the property of MoS2, which provides a new idea for designing efficient electrocatalysts doped with subgroup elements.

Boosting lithium storage of BaFe12O19 by element doping engineering

Boosting lithium storage of BaFe12O19 by element doping engineering

The effect of sputtering power on the structural and tribological behaviors at elevated temperature of Ta/Si co-doped DLC films

Ta and Si with various concentrations was co-doped into DLC films by plasma enhanced magnetron sputtering technique to improve its thermal stability and frictional performance at elevated temperature from 25 °C to 300 °C. Results showed that the doped Si and Ta mainly formed carbide in the film but play different role in the structure of the film. The sp3C content, surface roughness, hardness and adhesion strength increased firstly and then decreased with increasing content of doped elements in the film. The thermal stability and frictional performances at higher temperature was improved by higher content of doped element. It is notable that the film (with Si content of 4.47 at.% and Ta content of 2.44 at.%) exhibited low wear rates from 10−7 to 1 × 10−6 mm3/Nm at different temperatures owing to its higher sp3C content (18.2 %), proper nano-carbide, and thus higher hardness (11.09 GPa) and lower internal stress (0.24 GPa). The excellent frictional performances of this film tested at 300 °C was due to the reduced graphitization of the film, accompanied with the SiC nanoparticles and Ta5Si3 phase formed during the friction.

Improving the sensing performance of rambutan-like W18O49 based gas sensor for n-butanol by Ni doping

Element doping can improve the gas sensing performance of metal oxide semiconductor (MOSs). In this paper, the rambutan-like Ni-doped W18O49 are synthesized by one-step solvothermal route. The prepared Ni0.05W18O49 possesses larger specific surface area (130.5 m2g−1) and more plentiful oxygen vacancy than the pristine sample. Interestingly, compared with other sensors, the Ni0.05W18O49 sensor has the highest response (182.4) for 50 ppm n-butanol at 160℃ with short response-recovery time (14 s / 241 s). Moreover, the selectivity test shows that the Ni0.05W18O49 sensor has higher response for n-butanol than the other five volatile gases. The response value of the sensor to n-butanol is almost unchanged over five repeatability tests and the long-term stability tests.