X-ray Photoelectron Spectroscopy Research Articles

Operando Unveiling of Hydrogen Spillover Mechanisms on Tungsten Oxide Surfaces.

Hydrogen spillover is an important process in catalytic hydrogenation reactions, facilitating H2 activation and modulating surface chemistry of reducible oxide catalysts. This study focuses on the operando unveiling of platinum-induced hydrogen spillover on monoclinic tungsten trioxide (γ-WO3), employing ambient pressure X-ray photoelectron spectroscopy, density functional theory calculations and microkinetic modeling to investigate the dynamic evolution of surface states at varied temperatures. At room temperature, hydrogen spillover results in the formation of W5+ and hydrogen intermediates (hydroxyl species and adsorbed water), facilitated by Pt metal clusters. With increasing temperature, water desorption, reverse hydrogen spillover and surface-to-bulk diffusion of hydrogen atoms compete with each other, leading initially to reoxidation and then further reduction of W atoms in the near-surface. The combined experimental results and simulations provide a comprehensive understanding of the mechanisms underlying hydrogen interaction with reducible metal oxides, lending insights of relevance to the design of enhanced hydrogenation catalysts.

Effect of growth dynamics on the structural, photophysical and pseudocapacitance properties of famatinite copper antimony sulphide colloidal nanostructures (including nanosheets).

Facile phase selective synthesis of copper antimony sulphide (CAS) nanostructures is important because of their tunable photoconductive and electrochemical properties. In this study, off-stoichiometric famatinite phase CAS (fCAS) quasi-spherical and quasi-hexagonal colloidal nanostructures (including nanosheets) of sizes, 2.4-18.0 nm were grown under variable conditions of temperature (60-200 °C), time and oleylamine capping ligand concentration using copper(II) acetylacetonate and antimony(III) diethyldithiocarbamate precursors. Data from powder X-ray diffraction, Raman spectroscopy and high-resolution scanning/transmission electron microscopy confirm the tetragonal structure of the famatinite phase. X-ray photoelectron spectroscopy, transmission electron microscopy and scanning electron microscopy-energy dispersive X-ray spectroscopy data suggest a correlation of particle size, morphology and composition of the off-stoichiometric fCAS nanostructures with growth temperature and time, and oleylamine concentration. The off-stoichiometric Cu3-aSb1+bS4±c (a, b, c - mole fractions) nanostructures being severely copper-deficient and antimony-rich, exhibit shallow-lying acceptor copper vacancy states, deep-lying donor states of antimony interstitials, sulphur vacancies and antimony-copper antisites and shallow-lying acceptor surface trapping states. These electronic states are likely implicated in tunable UV-visible absorption and bandgaps between 2.3 and 2.8 eV, and broad visible-NIR photoluminescence with fast recombination of radiative lifetimes between 0.2 and 6.2 ns, confirmed from absorption, steady-state and time-resolved photoluminescence spectroscopies. Additionally, cyclic voltammetry and electrochemical impedance spectroscopy confirm that electrodes of the fCAS nanostructures display slightly variable pseudocapacitance of charge-storage primarily via possible sodium ion intercalation with a high specific capacitance of ∼84 F g-1 obtained at a scan rate of 5 mV s-1. Overall, these results show the influence of composition, in particular point defects, phase quality and morphology on the optical and pseudocapacitance properties of fCAS nanostructures, suitable as solar absorbers or electrodes for energy storage devices.

Electrosynthesis of Silane-Modified Magnetic Nanoparticles for Efficient Lead Ion Removal.

The removal of heavy metal ions, such as lead (Pb2+), from aqueous systems is critical due to their high toxicity and bioaccumulation in living organisms. This study presents a straightforward approach for the synthesis and surface modification of iron oxide nanoparticles (IONPs) for the magnetic removal of Pb2+ ions. IONPs were produced via electrosynthesis at varying voltages (10-40 V), with optimal magnetic properties achieved at 40 V resulting in highly crystalline and magnetic IONPs in the gamma-maghemite (γ-Fe2O3) phase. IONPs were characterized using various techniques including X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometry (VSM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). A novel electrochemical method was developed for the silanization of IONPs using tetraethoxysilane (TEOS), (3-mercaptopropyl)trimethoxysilane (MPTMS) and (3-aminopropyl)triethoxysilane (APTES). The resulting silane-modified IONPs were evaluated for the magnetic removal of Pb2+ ions, with TEOS-modified IONPs demonstrating superior performance. This material exhibited a high adsorption capacity of 519 mg/g at a Pb2+ ion concentration of 300 ppm, and high removal efficiency across a range of Pb2+ ion concentrations, attributed to its Fe2O3@SiO2 core-shell structure. This study highlights the potential of the electrochemical synthesis and silanization of nanoparticles for heavy metal remediation in water.

Hydrogen Sensing via Heterolytic H2 Activation at Room Temperature by Atomic Layer Deposited Ceria.

Ultrathin atomic layer deposited ceria films (< 20 nm) are capable of H2 heterolytic activation at room temperature, undergoing a significant reduction regardless of the absolute pressure, as measured under in-situ conditions by near ambient pressure X-ray photoelectron spectroscopy. ALD-ceria can gradually reduce as a function of H2 concentration under H2/O2 environments, especially for diluted mixtures below 10%. At room temperature, this reduction is limited to the surface region, where the hydroxylation of the ceria surface induces a charge transfer towards the ceria matrix, reducing Ce4+ cations to Ce3+. Thus, ALD-ceria replicates the expected sensing mechanism of metal oxides at low temperatures without using any noble metal decorating the oxide surface to enhance H2 dissociation. The intrinsic defects of the ALD deposit seem to play a crucial role since the post-annealing process capable of healing these defects leads to decreased film reactivity. The sensing behavior was successfully demonstrated in sensor test structures by resistance changes towards low concentrations of H2 at low operating temperatures without using noble metals. These promising results call for combining ALD-ceria with more conductive metal oxides, taking advantage of the charge transfer at the interface and thus modifying the depletion layer formed at the heterojunction.

Effect of silicone monomers on the properties of fluorinated acrylate pressure-sensitive adhesive for ePTFE bonding

Purpose Silicon-containing groups were introduced into fluoroacrylate polymer to further improve the comprehensive performance of pressure-sensitive adhesive (PSA) for expanded polytetrafluoroethylene (ePTFE) bonding. Design/methodology/approach A series of silicon-containing fluorinated acrylic copolymers were synthesized through free radical solution polymerization with vinyloxy trimethylsilane, allyltrimethylsilane, 3-(trimethoxysilyl)propyl methacrylate or 1,3,5-tris(3,3,3-trifluoropropyl) methylcyclotrisiloxane as silicon monomers, and comprehensive performance of the copolymers was evaluated based on Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), gel permeation chromatography, glass transition temperatures (Tg), differential scanning calorimetry, thermogravimetric analysis, water contact angle, the track, 180° peel strength, and shear holding power. Findings Based on the FTIR and XPS results, it is confirmed that the silicon monomers were successfully introduced into the fluorinated acrylate copolymer. XPS analysis indicated that the silicon groups had the tendency to enrich on the surface of the film, thereby reducing the F content on the film surface. The glass transition temperatures (Tg) of the PSAs increased when silicon monomers were introduced, while the thermal stability declined. The contact angles of the acrylic PSA films were increased with the introduction of silicon monomers. From the perspective of bonding performance, the track, 180° peel strength and shear holding power decreased to varying degrees compared to silicon-free PSA, except significantly elevated holding power with MPS as the silicon monomer. Originality/value Silicon-containing fluorinated acrylic copolymers were synthesized, and the comprehensive performance was evaluated as PSAs of ePTFE for the first time.

NiCo2O4/P,N‐doped Carbon with Engineered Interface to Improve the Rechargeability of Zn‐Air Batteries at High Energy Demands

The search for cost‐effective, high‐performance bifunctional catalysts for Zn‐air batteries (ZABs) requires extensive research into precious‐metal‐free materials. This study provides insight into the synergy between nickel cobaltite and P,N‐doped carbon modified through interface engineering by inducing oxygen vacancies in the spinel and non‐metallic heteroatoms in the carbon material. NiCo2O4 with various oxygen vacancy levels was synthesized via an ethylene glycol‐assisted solvothermal route. This resulted in significant changes in the structural and morphological properties, such as reduced crystallite size, lattice distortion, and increased oxygen vacancies, as observed from the physicochemical results. This was further verified by X‐ray photoelectron spectroscopy (XPS) and high‐resolution transmission electron microscopy (HR‐TEM), which showed a homogeneous dispersion of nickel cobaltite nanorods on the carbonaceous matrix, along with an increased concentration of pyridinic nitrogen and the formation of P–N and P–C bonds, both of which enhance electrocatalytic activity. NiCo2O4DI/P,N‐C exhibited superior discharge polarization behavior, achieving power and current densities of 124.4 mW cm−2 and 215.8 mA cm−2. The catalyst presented excellent stability (up to 100 h), while Pt‐IrO2/C lasted near 21 h. These results demonstrate the great potential of tailoring surface defects and heteroatom doping via interface engineering, resulting in high‐performance precious‐metal‐free electrocatalysts for long‐lasting and high‐efficiency ZABs.

Superior charge storage performance of optimized nickel cobalt carbonate hydroxide hydrate nanostructures for supercapacitor application

In our work, we report superior electrochemical performance of optimized 3D nanostructured, nickel-cobalt carbonate hydroxide hydrate (Ni3 − xCox-CHH (1 ≤ x ≤ 2)) materials with flower like morphology synthesised via one-step hydrothermal methods. A Ni rich sample (x = 1) demonstrate better specific capacitance and the improvement is attributed to more oxygen deficient neighbourhood of Ni compared to that of Co. The structural, morphological and electronic properties of the samples were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), High resolution transmission electron microscopy (HRTEM), field emission electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). A comprehensive characterization was used for physicochemical properties-electrochemical performance correlation. Cyclic voltammetry (CV), Galvanostatic charging and discharging (GCD) shows the supercapacitor feature of the samples for the composition containing the highest nickel concentration achieving a specific capacitance of 1649.51 F g− 1 at a current density of 1 A g− 1 and excellent rate capability of 1610.30 F g− 1 at a high current density of 5 A g− 1. The sample shows high cyclic stability of 80.86% after 3000 cycles. Improved specific capacitance is attributed to the synergy effect of bimetallic transition metals as well as improved surface area of flower like morphology. These findings show that Ni2Co-CHH electrode material demonstrates great potential as electrode material for supercapacitor device fabrication.

Preparation and Gas-Sensitive Properties of SnO2@Bi2O3 Core-Shell Heterojunction Structure

The SnO2@Bi2O3 core-shell heterojunction structure was designed and synthesized via a hydrothermal method, and the structure and morphology of the synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Based on the conclusions from XRD and SEM, it can be observed that as the hydrothermal temperature increases, the content of Bi2O3 coated on the surface of SnO2 spheres gradually increases, and the diameter of Bi2O3 nanoparticles also increases. At a hydrothermal temperature of 160 °C, the SnO2 spheres are fully coated with Bi2O3 nanoparticles. This paper investigated the gas-sensitive performance of the SnO2@Bi2O3 sensor towards ethanol gas. Gas sensitivity tests at the optimal operating temperature of 300 °C showed that the composite prepared at 160 °C achieved a response value of 19.7 for 100 ppm ethanol. Additionally, the composite exhibited excellent response to 100 ppm ethanol, with a response time of only 4 s, as well as good repeatability. The excellent gas-sensitive performance of the SnO2@Bi2O3 core-shell heterojunction towards ethanol gas is attributed to its p-n heterojunction material properties. Its successful preparation contributes to the realization of high-performance heterostructure ethanol gas sensors.

Fabrication of MoS2@Fe3O4 Magnetic Catalysts with Photo-Fenton Reaction for Enhancing Tetracycline Degradation

Tetracycline (TCs) is widely used in the treatment of human and animal infectious disease. TCs gives rise to a growing threat to the human health and environment protection due to its overuse. Therefore, it is important to remove TCs contaminants from waste effluents. In this work, MoS2@Fe3O4 catalytic material was fabricated by the simple hydrothermal method, which was applied in the photo-Fenton system to degrade TCs. The crystal structure, surface morphology, elemental composition, chemical state, electrochemical properties, and separability of MoS2@Fe3O4 catalytic materials were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), conventional and high-resolution transmission electron microscopy (TEM/HRTEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and vibrating sample magnetometry (VSM). Furthermore, MoS2@Fe3O4 could degrade 98.6% of TCs within 60 min under the optimum reaction conditions (the catalyst dosage of 3 g/L, H2O2 concentration of 5 mmol/L, the initial TCs concentration of 50 mg/L, and the initial pH of 5), which was a significant increase compared with pure Fe3O4. MoS2 can accelerate the Fe3+/Fe2+ cycle through electron transfer from Mo4+ to Fe3+, resulting in the improvement in the degradation efficiency of TCs. The quenching and electron paramagnetic resonance (EPR) results showed that OH• and photogenic hole h+ was the main active species in the photo-Fenton system. What is more, MoS2@Fe3O4 catalytic materials had remarkable stability and reusability, and can be handily regained via magnetic separation technology in a real scenario.

CO Adsorption on a Single-Atom Catalyst Stably Embedded in Graphene.

Confined single metal atoms in graphene-based materials have proven to be excellent catalysts for several reactions and promising gas sensing systems. However, whether the chemical activity arises from the specific type of metal atom or is a direct consequence of the confinement itself remains unclear. In this work, through a combined density functional theoryand experimental surface science study, we address this question by investigating Co and Ni single atoms embedded in graphene (Gr) on a Ni(111) support. These two single atom catalysts (SACs) exhibit opposite behavior toward carbon monoxide (CO) gas molecules: at RT, CO binds stably to Co, whereas it does not to Ni. We rationalize this difference by the energy position oftrapped metal dxz and dyz states involved in π backdonation to CO: while for Co, these states lie at the Fermi level, for Ni are located deep below it. This conclusion is corroborated by a proof-of-concept experiment, where a Gr/Ni(111) sample containing both stable Ni and Co single atoms was exposed to a CO partial pressure of 5 ‧ 10-7 mbar. Scanning tunnelling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and temperature programmed desorption (TPD) measurements confirm the selective adsorption of CO on Co at RT.

Toward Surface Passivation of Black Phosphorus via a Self-Assembled Ferrocene Molecular Layer.

Black phosphorus (BP), a promising two-dimensional material, faces significant challenges for its applications due to its instability in air and water. Herein, molecular dynamics simulations reveal that a self-assembled ferrocene (FeCp2) molecular layer can form on BP surfaces and remain stable in aqueous environments, predicting its effectiveness for passivation. This theoretical finding is corroborated by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and optical microscopy observations. In addition, atomic force microscopy analysis confirms that ferrocene-passivated BP flakes with thicknesses of <10 nm exhibit minimal degradation over 25 days. Density functional theory calculations further show that ferrocene stabilizes BP and modulates its band gap, improving its electronic applicability. Notably, we find that the passivation of BP by metallocenes is universal because other metallocenes (VCp2, MnCp2, and NiCp2) exhibit similar adsorption behaviors. These findings underscore the potential of metallocenes as versatile protective layers for BP and other materials that are not stable in air.

Fermi Level Equilibration and Charge Transfer at the Exsolved Metal-Oxide Interface.

Exsolution is a promising approach for fabricating oxide-supported metal nanocatalysts through redox-driven metal precipitation. A defining feature of exsolved nanocatalysts is their anchored metal-oxide interface, which exhibits exceptional structural stability in (electro)catalysis. However, the electronic interactions at this unique interface remain unclear, despite their known impact on catalytic performance. In this study, we confirm charge transfer between the host oxide and the exsolved metal by demonstrating a two-stage Fermi level (EF) evolution on SrTi0.65Fe0.35O3-δ (STF) during metallic iron (Fe0) exsolution. Combining ambient pressure X-ray photoelectron spectroscopy with theoretical analysis, we show that EF initially rises due to electron doping from oxygen vacancy formation in STF. Subsequently, upon Fe0 precipitation, EF stabilizes and becomes insensitive to further oxygen release in STF, driven by EF equilibration and charge transfer between STF and the exsolved Fe0. These findings highlight the importance of considering electronic metal-support interactions when optimizing exsolved nanocatalysts.

Sodium Trithiocarbonate as a Promising Sulfidizing Agent for Efficient and Green Recovery of Azurite: Flotation Properties and Interaction Mechanism.

The sulfidization-xanthate flotation process has been used commercially with some success in recovering azurite, but it remains unsatisfactory in terms of the environmental impact and flotation index. To remediate these deficiencies, this study evaluated the flotation performance of sodium trithiocarbonate (Na2CS3) as a green sulfidizing agent for azurite. Flotation test results demonstrated that Na2CS3 has the same efficacy as sodium sulfide but markedly superior activation performance. At one-fifth the dose, the maximum flotation recovery for Na2CS3 is about 20 percentage points higher than that observed for sodium sulfide. Contact angle measurements and field emission scanning electron microscopy analysis revealed that Na2CS3 modifies the pristine azurite surface by forming a relatively uniform sulfur-rich layer composed of nanoparticles, which in turn increases the collector efficacy and thus improves flotation recovery. The results of X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry further suggest that this sulfur-rich hydrophobic layer could be cuprous trithiocarbonate. The reduction of Cu(II) in the azurite lattice is considered a key step in forming the sulfur-rich layer, and the resultant Cu(I) interacts with Na2CS3 through the latter's carbon-sulfur bonds. The results of this study will facilitate the development of better technologies to process copper oxide ores.

Influence of zinc oxide nanoparticles on the carbon accumulation on silver exposed to carbon dioxide hydrogenation reaction conditions.

The strong influence of surface adsorbates on the morphology of a catalyst is exemplified by studying a silver surface with and without deposited zinc oxide nanoparticles upon exposure to reaction gases used for carbon dioxide hydrogenation. Ambient pressure X-ray photoelectron spectroscopy and scanning tunneling microscopy measurements indicate accumulation of carbon deposits on the catalyst surface at 200 °C. While oxygen-free carbon species observed on pure silver show a strong interaction and decorate the atomic steps on the catalyst surface, this decoration is not observed for the oxygen-containing species observed on the silver surface with additional zinc oxide nanoparticles. Annealing the sample to temperatures above 350 °C removes the contaminants by hydrogenation to methane.

Modulation of RuO2 Nanocrystals with Facile Annealing Method for Enhancing the Electrocatalytic Activity on Overall Water Splitting in Acid Solution.

RuO2-based materials are considered an important kind of electrocatalysts on oxygen evolution reaction and water electrolysis, but the reported discrepancies of activities exist among RuO2 electrocatalysts prepared via different processes. Herein, a highly efficient RuO2 catalysts via a facile hydrolysis-annealing approach is reported for water electrolysis. The RuO2 catalyst dealt with at 200 °C (RuO2-200) performs the highest activities on both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acid with overpotentials of 200 mV for OER and 66 mV for HER to reach a current density of 100 mA cm-2 as well as stable operation for100 h. The high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) characterizations show that the activities of as-prepared RuO2 rely on the hydroxide group/lattice oxygen (OH-/O2-) ratio, size, and crystalline of RuO2. The density functional theory (DFT) calculation also reveal that the OH- would enhance the activities of RuO2 for HER and OER via modifying the electronic structure to facilitate intermediate adsorption, thereby reducing the energy barrier of the rate-determining step. The water electrolysis by using RuO2-200 as the catalyst on both anode and cathode demonstrates a stable generation of hydrogen and oxygen with high Faradic efficiency at a current density of ≈30 mA cm-2 and a potential of below 1.47 V.

Exploring the role of volume energy density in altering microstructure and corrosion behavior of nitinol alloys produced by laser powder bed fusion

In the realm of materials science and engineering, the pursuit of advanced materials with tailored properties has been a driving goal behind technological progress. Scientific interest in laser powder bed fusion (L-PBF) fabricated NiTi alloy has in recent times seen an upsurge of activity. In this study, we investigate the impact of varying volume energy density (VED) during L-PBF on the microstructure and corrosion behaviour of NiTi alloys in both scan (XY) and built (XZ) planes. The microstructural evolution in both planes was characterized by electron backscatter diffraction and phase change temperatures were characterized using differential scanning calorimeter measurements. Electrochemical experiments were carried out to compare the specimens produced at high laser energy density and low laser energy density. The results indicate that employing high laser energy density in the production of NiTi alloy induces discontinuous dynamic recrystallization, contributing to grain refinement. This in turn enhances the corrosion resistance of the specimen. X-ray photoelectron spectroscopy was employed to examine the type of oxide layer that developed on the samples. The increased resistance to corrosion in a high laser energy density sample can be associated with the formation of a stable and homogeneous passive layer with enriched TiO2 as opposed to Ti2O3. This exploration has unravelled the intricate relationship between VED, the microstructure, and the corrosion properties of L-PBF fabricated NiTi alloys, offering valuable insights into their performance for diverse applications.

Enhanced Ciprofloxacin Ozonation Degradation by an Aqueous Zn-Cu-Ni Composite Silicate: Degradation Performance and Surface Mechanism

This study investigates the environmental significance of ciprofloxacin as an emerging contaminant and the need for effective degradation methods. The chemical coprecipitation method was used in this study to prepare the Zn-Cu-Ni composite silicate, serving as a heterogeneous ozonation catalyst. The catalytic activity was then evaluated by degrading ciprofloxacin (CIP). Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption–desorption, and Fourier transform infrared analysis (FTIR) were used to characterize the Zn-Cu-Ni composite silicate. The catalyst had a high surface area (308.137 m2/g), no regular morphology, and a particle size of 7.6 µm and contained Si-O-Si, Ni-O-Si, and Zn-O-Si. The results showed that the CIP degradation and mineralization rates (pH 7.0, CIP 3.0 mg/L, Ozone 1.5 mg/L) were significantly enhanced in the presence of the Zn-Cu-Ni composite silicate. The CIP and total organic carbon (TOC) removal rates were increased by 51.09% and 18.72%, respectively, under optimal conditions, compared with ozonation alone. The adsorption of Zn-Cu-Ni composite silicate, ozone oxidation, and ·OH oxidation synergistically promoted the efficient removal of CIP. This study provides valuable catalytic ozone technology for degradation of antibiotics in wastewater to reduce environmental pollution with potential practical applications.

Dissociation-Precipitation Chemistry of Lithium Polysulfides and Its Correlation to Dynamic Evolution of Cathode-Electrolyte Interphase in Highly Solvating Electrolyte.

Lithium-sulfur (Li-S) batteries has been regarded as one of the most promising next-generation energy storage systems due to their high theoretical energy density. However, the practical application of Li-S batteries is still hindered by the unstable cathode-electrolyte interphase and the early passivation of charge product (Li2S), leading to poor cycling stability and low S utilization. Herein, we propose an electrolyte engineering strategy using highly solvating hexamethylphosphoramide (HMPA) as a co-solvent to elucidate the dissociation-precipitation chemistry of lithium polysulfides (LiPSs). The multimode optical spectroscopies confirm that this electrolyte engineering is able to effectively regulate the solvation of LiPSs to initiate a radical-assisted conversion pathway and control three-dimensional (3D) Li2S electrodeposition to boost sulfur utilization. More importantly, the dynamic evolution of cathode-electrolyte interphase, featuring with S-/P-containing species, is also assessed by both distribution of relaxation times technology and X-ray photoelectron spectroscopy, which can suppress the passivation of Li2S to enhance conversion reversibility. As a proof-of-concept, a Li-S cell with high S loading mass of 7.75 mg cm-2 demonstrates an extremely high area capacity of 7.86 mAh cm-2 at a current density of 1.30 mA cm-2 , representing a significant advancement in promoting the development of practical high-energy-density Li-S batteries.

Green Synthesis of Red Fluorescent Carbon Quantum Dots: Antioxidant, Hemolytic, Biocompatibility, and Photocatalytic Applications.

A straightforward one-step hydrothermal method is introduced for synthesizing highly efficient red fluorescence carbon dots (R-CQDs), utilizing Heena leaf (Lawsonia inermis) powder as the carbon precursor. The resulting R-CQDs exhibit excitation at 540nm and emission at 675nm, a high absolute photoluminescence (PL) with quantum yield of 40% in ethanol. Various physicochemical characterization was employed to confirm successful formation of R-CQDs including UV-Vis Spectroscopy, Fourier Transform Infrared (FT-IR) Spectroscopy, X-ray diffraction Spectroscopy, Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy. The optimization of synthesis parameters including synthesis method, effect of reaction temperature, effect of reaction time and effect of reaction concentration have a significant impact on the quality and quantity of synthesized R-CQDs, as well as their properties and applications. The effect of pH and UV radiation on synthesized R-CQDs exhibited excellent photo and chemical stability. Furthermore, R-CQDs had a high ability to protect cells from hydrogen peroxide-induced damage by scavenging hydroxyl radicals.In antioxidant activity, all three methods show approximately 80% of DPPH, Fenton's reaction and KMnO4 scavenging activity. In hemolytic assay shows no damage or destruction of red blood cells after exposure of R-CQDs. Cell viability and angiogenesis assays confirmed the biocompatibility of the R-CQDs, indicating that they might be useful as agents for cell labelling and useful for bioimaging probe. In dye degradation activity shows highest % of dye degradation in eosin and fluorescein with approximately 80% of dye degradation by using R-CQDs.

4,4′,4″-Tris(Diphenylamino)Triphenylamine: A Compatible Anion Host in Commercial Li-Ion Electrolyte for Dual-Ion Batteries

Dual-ion batteries (DIBs) were demonstrated as a promising technology for large-scale energy storage due to their low cost, recyclability, and impressively fast charge capability. Graphite as a commonly used cathode material in DIBs, however, suffers from poor compatibility with commercial Li-ion electrolytes and graphite anodes, making it difficult to directly utilize the well-established infrastructure for Li-ion batteries. Herein, we report a small aromatic amine molecule 4,4′,4″-tris(diphenylamino)triphenylamine (N4) functioning as a compatible anion host in the EC-containing Li-ion electrolyte. With an average discharge voltage of 3.6 V (vs. Li+/Li), the N4 electrode delivers a reversible specific capacity of 108 mAh/g, which is much higher than 29 mAh/g for the graphite cathode at the same condition. The high capacity retention of 91.3% was achieved after 500 cycles at 1 A/g. The N4 electrode also exhibited good rate performance. Via different characterization techniques like Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, the energy storage mechanism of N4 was revealed as a conversion between amine and quaternary amine cations, accompanied by PF6− (de-)insertion. As consequences, the assembled N4||graphite DIB w showed a high discharge capacity of 90 mAh/g within 1.5–4.1 V, and good cycling stability with a 98% capacity retention after 40 cycles. Decent rate performance was achieved in the N4||graphite DIB as well. This work provides new insights into designing a compatible anion host for affordable DIBs.