Charge Density Properties Research Articles

Lithium in drinking water: Review of chemistry, analytical methods, and treatment technologies

AbstractLithium was included in the fifth Unregulated Contaminants Monitoring Rule, signaling the Environmental Protection Agency's interest in regulating lithium. Many questions regarding occurrence, health effects, and treatability of lithium exist. This review primarily focuses on the relationship between lithium chemistry and treatability. Sampling indicates nationwide lithium occurrence in drinking water. Yet, lithium is not included in the Integrated Risk Information System, reflecting a lack of censuses regarding its health effects. Aqueous lithium is a monovalent cation with size, charge density, and solubility properties that present treatment challenges. Lithium's growing economic value is stimulating new extraction and isolation technologies, but these may not be transferable to drinking water treatment. Currently, reverse osmosis is the only full‐scale drinking water treatment technology that can reliably remove significant levels (>50%) of lithium. Focusing future research efforts on electrodialysis and inorganic ion sieves may yield significant gains in effectiveness and readiness for the drinking water industry.

Computational analysis of 1T-MoS2: Probing the interplay of layer-dependent electronic structure, quantum capacitance, charge density and mechanical properties

To meet the high energy demand of society, a conversion to renewable energy sources has become essential and energy should be appropriately stored for future use. This has led to the development of energy-storing devices such as supercapacitors (SCs). To enhance capacitive behavior, the concept of quantum capacitance (CQ) is unveiled, which results from the confinement of electrons in their energy states. In this work, 1T phase of MoS2 is studied as it has received a lot of attention because of its wide applications in the energy storage devices and electronics. Here, the electronic structure, CQ and surface charge density (σ) of one, two and three-layered structures of 1T phase is studied using Density Functional Theory. No bandgap is obtained in the Density of States (DOS) and the bands plot of 1T structure indicates their metallic character and the DOS is continuous in all three layers. The CQ of three-layered structure dominates over the other two layers throughout the potential window. The larger CQ and σ values are obtained as 1718.06 μF cm−2 and -1299.50 μC cm−2 for three-layered structure at −0.27 V and −1 V respectively. For analyzing the mechanical strength, Young's modulus is evaluated for optimized structure by applying uni-axial strain. The value is obtained as 177.37 GPa, which is a measure of elastic deformation behavior. The results suggest that the capacitive performance of 1T MoS2 for SC applications is better and it can function as flexible cathode material for asymmetric SC applications.

Mechanism of glycine and H2O action in tribochemical mechanical polishing of single-crystal gallium nitride substrate

With the rapid development of the third-generation semiconductors, environmentally friendly tribochemical mechanical polishing (TCMP) is in urgent need and has been a research hot-spot. In this work, the mechanism of glycine (Gly) and H2O action in TCMP of single-crystal gallium nitride (SC-GaN) substrate is systematically studied. The experimental results indicate that the TCMP of SC-GaN substrate with 0.75 wt% Gly exhibits a higher surface quality and a 3-fold improvement in material removal rate than that with H2O. Based on first-principle calculations, the geometric configurations and interfacial interactions of the Gly/SC-GaN and H2O/SC-GaN heterostrutures are further explored. Charge transfer analysis shows that SC-GaN with lattice distortion of 0.4 Å transfers more electrons into Gly (0.202 e) than into H2O (0.128 e), which suggests the reaction between SC-GaN and Gly is more intense under friction by abrasives. The research of differential charge density and geometric properties (bond angles etc.) demonstrates that the –COOH functional group (Gly) has a higher reactivity than the –OH functional group (H2O). Based on the above findings, a microscopic material removal model for the TCMP of SC-GaN substrate with Gly is established. These results have potential applications in the semiconductor and microelectronics industries.

Flexible, wearable triboelectric rubber with tunable surface charge density enabled by regulation of surface functional group density and permittivity

Flexible wearable triboelectric nanogenerator (TENG) has attracted immense interest in various application scenarios due to its intrinsic self-powered characteristics. Recently, rubbers with high elasticity are frequently reported to be favored substrates for wearable smart devices to enhance body comfort and contact effects. However, most commercial rubbers are nonpolar and lack of enough polar functional groups even after physical and chemical modification to earn satisfactory surface charge density for high triboelectric performance. Moreover, the combination of high triboelectric and mechanical properties is still a significant challenge for flexible TENG material. In this work, a flexible triboelectric rubber with tunable surface charge density and excellent mechanical properties is demonstrated via a natural polymer assisted dispersion of perovskite nanofiller strategy. The designed rubber-based TENG shows an excellent 310 V triboelectric output, 106 nC transferred charge and 6.14 W·m−2 power density, as well as a favorable mechanical property of 10.69 MPa Young’s modulus and 211 % strain. The material can harvest mechanical energy and charge 1 μF commercial capacitors to 1.8 V in 60 s from nature. When serves as flexible device, it can also self-powered to real-time monition various human behavior and distinguish different speed of vehicle driving conditions. We expect our works will provide a feasible strategy to significantly improve the comprehensive performance of flexible wearable rubber-based TENG and advance the potential application of rubber.

Mica/nylon composite nanofiber film based wearable triboelectric sensor for object recognition

The wearable sensors have essential impacts on the progress of intelligent technology, while the traditional sensors cannot meet the sensitivity requirements. Here, we propose a high performance intelligent triboelectric wearable sensor (HITWS) by Mica/Nylon composite nanofiber film (MCNF), which is fabricated by the electrospinning and dielectric particle doping process. The addition of Mica particles effectively improves the dielectric constant, surface charge density and functional group properties of MCNF and further optimizes its positive triboelectric properties. Therefore, the HITWS demonstrates significantly higher signal-to-noise ratio, sensitivity and power density (11.82 W/m2) compared to previous similar studies. Furthermore, based on HITWS, 4-channel STM32 signal acquisition and deep learning algorithm, an intelligent tactile sensing system is achieved. Combined with the structurally optimized VGG16 network model, the recognition of 7 kinds of objects can reach an average accuracy of 96.57 %. This work provides new idea and method for the development of applications based on object recognition, such as remote interaction, medical prosthetics and smart robots.

Biomimetic and electrostatic self-assembled nanocellulose/MXene films constructed with sequential bridging strategy for flexible supercapacitor

Despite the two-dimensional titanium carbide MXene (Ti3C2Tx) has shown promising applications in energy storage, the inherent self-stacking and weak connectivity among nanosheets present a challenge in manufacturing robust MXene films for emerging flexible supercapacitors. Herein, inspired by the robust “soft-hard” structured exoskeletons of crustaceans, the biomimetic cellulose nanofibers (CNFs)/MXene-Al (CM-Al) film with integrated high mechanical toughness, electroconductivity and electrochemical behavior, sequential bridging with hydrogen and ionic bonds, is crafted via the facile electrostatic self-assembly strategy. The embedded CNFs guide the in-plane orientation of MXene through hydrogen bonding, forming a “soft-hard” microstructure and dramatically enhancing the mechanical toughness of CM-Al. The rigid ionic bonds established between the oxygen-containing groups on CNFs and MXene with Al3+ further elevate the mechanical strength (163.88 MPa) and act as additional electron transfer channels to impart the reinforced electroconductivity (82.63 S cm−1). Benefiting from the more active site exposure induced by the expanded MXene layer spacing after CNFs embedding and the weakened intrinsic resistance caused by the constructed ionic bonding, the assembled flexible quasi-solid-state symmetric supercapacitor with CM-Al as electrode delivers a high area capacitance (679 mF cm−2), energy density (16.2 μWh cm−2), cycling capability (85.3 % capacitance retention after 10,000 cycles) and intrinsic tolerance to various non-stretching deformations. Moreover, the selective principles for metal ions are summarized that involved a comprehensive consideration of ionic radius, charge density and basic chemical properties. This work demonstrates an accessible and feasible construction strategy for flexible composite films and provides an alternative pathway for wearable energy storage devices.

Exploring optoelectronic and thermal characteristics of Janus MoSeTe and WSeTe monolayers under mechanical strain

This paper reveals the effect of external strain on the electronic, thermal and optical properties of Janus MSeTe (M=Mo, W) using first principles. Phonon spectrum calculations confirm the dynamic stability of the system. Biaxial stretching can effectively modulate its thermal properties. Uniaxial, biaxial and shear strains modulate the band structure, structural parameters, averaged differential charge density and optical properties of the MSeTe system to different degrees. The increase of compressive and shear strains leads to a gradual decrease of the band gap and triggers a semiconductor-metal phase transition at the critical point. The intrinsic system exhibits strong light absorption in the visible and ultraviolet regions, while strain induces a redshift of the light-absorbing edge, which enhances the response to the infrared and visible wavelength bands. These findings provide a theoretical basis and application potential for the design of optoelectronic devices and thermoelectric materials.

In-depth analysis of γ-CuI as an HTM for perovskite solar cells: A comprehensive DFT study of structural, elastic, mechanical, charge density, and optoelectronic properties

Herein, we employed Density Functional Theory (DFT) to comprehensively investigate pristine γ-CuI properties under two computational schemes: Generalized Gradient Approximation (GGA) and GGA + Hubbard correction. Structural stability is rigorously assessed through ground state energy optimization, complemented by a meticulous examination of elastic constants to confirm mechanical stability. Later on, we analyzed the electronic properties, as well as the optical properties, incorporating parameters such as the extinction coefficient that was low and refractive index that was high in the IR and visible regions. Notably, γ-CuI exhibits low reflectivity and absorption in the critical regions of interest. Our findings demonstrate that γ-CuI can serve as a cost-effective Hole Transporting Material (HTM), effectively reducing optical losses in perovskite solar cells.

The electronic structure, electronic charge density, optical and thermoelectric properties of Mo and Rh based triple perovskite semiconductors Ba3CaNb2O9 for low-cost energy technologies

The electronic structure, electronic charge density, optical and thermoelectric properties of Mo and Rh based triple perovskite semiconductors Ba3CaNb2O9 for low-cost energy technologies

Effect of Ni-doped on switching mechanisms and characteristics of ZnO-based memristor: Experimental and first-principles investigations

In this paper, we explore the impact of Ni doping on the resistive switching (RS) performance of ZnO-based resistive random access memory (RRAM). The Ti/ZnO: Ni/ITO resistive memory exhibits a reduced and less discrete forming voltage (Vforming) and set voltage (Vset), along with a more stable high resistance state (HRS). The doping does not change the conductivity mechanism of the device. The observed outcomes can be attributed to the influence of Ni doping on the generation and breakage of the oxygen vacancy conductive filaments (CF) in the vicinity. Using First-Principles calculations, we calculated the formation energy of oxygen vacancies (Vos), the band structure, the density of states (DOS), charge density, and electronic properties of the doped ZnO cell. The oxygen vacancy formation energy (Efv) is significantly lower in the Ni-doped ZnO cell, which is associated with lower Vforming and Vset. And it allows for less randomness in the generation of CF, which improves the stability of the HRS. The band structure shows that Ni doping can add an additional band at the Fermi energy level of ZnO, corresponding to the defect states in the density of states. The improved storage capacity of Ni-doped ZnO devices has been experimentally demonstrated.

A DFT study of detection of toxic gases (Cl2, SO2, HCHO, NH3) by SnS2 monolayer modified with Ag2O(1,2) cluster

Based on density functional theory (DFT), the adsorption behaviour of Ag2O(1,2) modified SnS2 monolayer on toxic gases (Cl2, SO2, HCHO, NH3) was analysed. The optimal structure, differential charge density, state density and other adsorption properties of the adsorption system were studied, and it was found that Ag2O(1,2)-SnS2 was still stable. Moreover, the modification of Ag2O(1,2) group improves the conductivity of SnS2, and the gas sensitivity increases with the increase of the number of groups. The energy gap, recovery time, response time, sensitivity and work function are also analysed for the further study of gas adsorption properties. It can be concluded that the optimum recovery time is easier for Ag2O-SnS2 at high temperature, and the greater sensitivity and the greater variation of the work function also reflect the better adsorption performance of Ag2O-SnS2. The results show that Ag2O(1,2)-SnS2 has the potential to become the adsorbent of some toxic gases, and has certain practical significance for air purification and ecological environment protection.

A systemic study on Thallium based 3D halide perovskite with enhanced figure of merit

First principles calculations are carried out to explore structural, elastic, electronic, charge density and thermoelectric properties of TlZnX3 (X = F, Cl, Br and I) 3D halide cubic perovskites within the Generalized Gradient Approximation (GGA) through Quantum Espresso code. The elastic coefficients (C11, C12 and C44) and elastic modulii such as Young’s modulus, bulk modulus, shear modulus reveals that stiffness is higher in TlZnF3. Additionally using Pugh’s ratio and Cauchy’s pressure TlZnF3 is classified as ductile whereas TlZnX3 (X = Cl, Br and I) are classified as brittle materials. Phonon dispersion curve proves the dynamic stability of TlZnF3. The band structures of TlZnX3 (X = F, Cl and Br) and TlZnI3 shows semiconducting and metallic nature respectively. Due to replacement of halide ion the indirect band gap of TlZnX3 (X = F, Cl and Br) decreases from 3.82 eV, 1.39 eV and 0.37 eV as the size of the anion increases. Using the Boltztrap code, thermoelectric parameters are analysed at temperatures of 400 K, 600 K and 800 K and chemical potential provides insight about optimal dopant. Large Seebeck Coefficient combined with ultra low thermal conductivity results in a high figure of merit for TlZnF3 that satisfies industry standards (ZT ≈ 1). Together, these outcomes highlights that these Thallium based halide perovskite are reliable materials for high temperature thermoelectric devices.

Covalent functionalization of electrochemically exfoliated 1T-MoS2 nanosheets for high-performance supercapacitor electrode

Covalently functionalized 1T-MoS2 (Fc-1T-MoS2) nanosheets are synthesized by the chemical reaction between electrochemically exfoliated 1T-MoS2 nanosheets and iodobenzene. The NH2Ph ring functionality and 1T-MoS2 phase improves the electrochemical performance for supercapacitors by enhancing the charge density and electronic properties, which leads to fast charge transport and high charge storage capacity. The Fc-1T-MoS2 has a high specific capacitance of 501 F g−1 at a current density of 1 A g−1 with capacitance retention of 76.32% after 2000 cycles, which is 2.6 times of magnitude higher than that of bare 1T-MoS2 nanosheets. This study exposes the effect of functionalization of MoS2 nanosheets for supercapacitor applications.

Invesigation of the electronic structure and Optoelectronic properties of Si-doped <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> using GGA+U method based on first-principle

In this work, the formation energy, band structure, state density, differential charge density and optoelectronic properties of undoped and Si doped <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> are calculated using GGA+U method based on density functional theory. The results show that the Si-substituted tetrahedron Ga(1) is more easily synthesized in experiments, and the obtained <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> band gap and Ga 3d state peak are in good agreement with the experimental results, and the effective doping is more likely to be obtained under oxygen-poor conditions. After Si doping, the total energy band moves to the low-energy end, and Fermi level enters the conduction band, showing n-type conductive characterastic. Si 3s orbital electrons occupy the bottom of the conduction band, the degree of electronic coocupy is strengthened, and the conductivity is improved. The dielectric function ε2(ω) results show that with the increase of Si doping concentration, the ability to stimulate conductive electrons first increases and then decreases, which is in good agreement with the quantitative analysis results of conductivity. The optical band gap increases and the absorption band edge rises slowly with the increase of Si doping concentration. The results of absorption spectra show that Si-doped <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> has strong deep ultraviolet photoelectric detection ability. The calculated results provide a theoretical reference for the further experimental investigation and the optimization innovation of Si-doped <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> and relative device design.

Investigation of electronic structure and optoelectronic properties of Si-doped <i>β</i>-Ga<sub>2</sub>O<sub>3 </sub>using GGA+<i>U</i> method based on first-principle

In this work, the formation energy, band structure, state density, differential charge density and optoelectronic properties of undoped <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> and Si doped <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> are calculated by using GGA+<i>U</i> method based on density functional theory. The results show that the Si-substituted tetrahedron Ga(1) is more easily synthesized experimentally, and the obtained <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> band gap and Ga-3d state peak are in good agreement with the experimental results, and the effective doping is more likely to be obtained under oxygen-poor conditions. After Si doping, the total energy band moves toward the low-energy end, and Fermi level enters the conduction band, showing n-type conductive characteristic. The Si-3s orbital electrons occupy the bottom of the conduction band, the degree of electronic occupancy is strengthened, and the conductivity is improved. The results from dielectric function <i>ε</i><sub>2</sub>(<i>ω</i>) show that with the increase of Si doping concentration, the ability to stimulate conductive electrons first increases and then decreases, which is in good agreement with the quantitative analysis results of conductivity. The optical band gap increases and the absorption band edge rises slowly with the increase of Si doping concentration. The results of absorption spectra show that Si-doped <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> has the ability to realize the strong deep ultraviolet photoelectric detection. The calculated results provide a theoretical reference for further implementing the experimental investigation and the optimization innovation of Si-doped <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> and relative device design.

New Advances in Biomedical Application of Polymeric Micelles

In the last decade, nanomedicine has arisen as an emergent area of medicine, which studies nanometric systems, namely polymeric micelles (PMs), that increase the solubility and the stability of the encapsulated drugs. Furthermore, their application in dermal drug delivery is also relevant. PMs present unique characteristics because of their unique core-shell architecture. They are colloidal dispersions of amphiphilic compounds, which self-assemble in an aqueous medium, giving a structure-type core-shell, with a hydrophobic core (that can encapsulate hydrophobic drugs), and a hydrophilic shell, which works as a stabilizing agent. These features offer PMs adequate steric protection and determine their hydrophilicity, charge, length, and surface density properties. Furthermore, due to their small size, PMs can be absorbed by the intestinal mucosa with the drug, and they transport the drug in the bloodstream until the therapeutic target. Moreover, PMs improve the pharmacokinetic profile of the encapsulated drug, present high load capacity, and are synthesized by a reproducible, easy, and low-cost method. In silico approaches have been explored to improve the physicochemical properties of PMs. Based on this, a computer-aided strategy was developed and validated to enable the delivery of poorly soluble drugs and established critical physicochemical parameters to maximize drug loading, formulation stability, and tumor exposure. Poly(2-oxazoline) (POx)-based PMs display unprecedented high loading concerning water-insoluble drugs and over 60 drugs have been incorporated in POx PMs. Among various stimuli, pH and temperature are the most widely studied for enhanced drug release at the site of action. Researchers are focusing on dual (pH and temperature) responsive PMs for controlled and improved drug release at the site of action. These dual responsive systems are mainly evaluated for cancer therapy as certain malignancies can cause a slight increase in temperature and a decrease in the extracellular pH around the tumor site. This review is a compilation of updated therapeutic applications of PMs, such as PMs that are based on Pluronics®, micelleplexes and Pox-based PMs in several biomedical applications.

Quantum Mechanical Calculations and Electrochemical Study of Vibrational Frequencies, Energies in Some Flavonoids molecules

Quantum mechanical computations is conducted using DFT (Density Functional Theory) and PM3 (Parameterized Model 3), also, using DFT of (B3LYP) with a 6-311++G (d, p) with G09 application. These molecular three components include structure, electronic charge density and energetic characteristics of chosen phytomedicine compounds. The impact of functional groups on physical characteristics were studied using myricetin, linebacker, and flavone because of their chemical structures. For phytomedicine compounds, we utilized quantum mechanical simulations to estimate bond length, energy, vibration(vib.) modes, charge density and mechanical properties (cruelty, strength, stiffness, for the measurements of the lengths and energy of the bonds). Herzberg convention is used to look for the connections between the frequencies of similar modes which was used. IR absorption of the highest vibration frequencies modes of 3N-6 was measured and assigned for all species. Physical parameters were also calculated these include: heat of production, amount of energy, atomic electronic charge density, dipole moment and (E gap) (E = ELUMO-EHOMO). For three phytomedicine molecules, quantum chemical properties were combined. This software also computed and evaluated the electronic charge density distribution on atoms of 3 molecules. The equilibrium geometries of all three molecules were studied.

Transport Properties of Novel LaCoTiIn Equiatomic Quaternary Heusler Alloy for Thermoelectric Energy Conversion

The emergence of new thermoelectric materials for energy generation is crucial to satisfying the world's energy demand. The electron charge density and thermoelectric transport properties of the LaCoTiIn quaternary Heusler alloy were investigated in this study. We used the Generalized Gradient Approximation (GGA – PBE) exchange correlation potential to illustrate the physical properties of a material. The electronic structure of the alloy shows half-metallic ferromagnetic behavior. The minority spin channel's small band gap enhances its thermoelectric characteristics. The high electrical conductivity, small thermal conductivity, and good figure of merit all indicate that this material could be a suitable material to employ in thermoelectric energy conversion.

Effect of Ca2+ doping on the electronic charge density and magnetic properties of ZnFe2O4 spinel ferrites

Effect of Ca2+ doping on the electronic charge density and magnetic properties of ZnFe2O4 spinel ferrites

Density Functional Theory Studies on Effects of Additive Hydration on Neutral and Zwitterionic Glycylalanine

The density functional theory computations have been carried out to study the effect of stepwise hydration on the structures of various conformers of the Neutral Glycylalanine…(Water) n (NGA…(W) n ) (n=5-10) and Zwitterionic Glycylalanine...(Water) n (ZGA…(W)n) (n=5-9) clusters. This indicates that the most stable neural GA conformer is 50.2 kcal/mol lower in energy than its zwitterionic counterpart. The hydrogen bonding interaction energies with BSSE corrections have been analyzed. Starting from complexation with six water molecules, ZGA complexes turn out to be the most stable candidates than their neutral partners. Theories of Bader’s Atoms in Molecules (AIM) and Natural Bond Orbital (NBO) are applied to examine the hydrogen bonds in the solvated complexes. In all hydrated complexes, the N-H (amino group)-Ow and O15-H16… Ow bonds are observed to be relatively short and possess comparatively higher values of (r) and (r). A good correlation between the structural parameters and the properties of charge density is found.