Wide Window Research Articles

Harmonizing Wide Voltage Window and High Energy Density toward Asymmetric All-Solid-State Supercapacitor.

All-solid-state supercapacitors are known for their safety, stability, and excellent cycling performance. However, their limited voltage window results in lower energy density, restricting their widespread application in practical scenarios. Therefore, in this work, CC/MoO3@Ti3C2Tx negative electrode and Mo1Al1-MnO2/CC positive electrode materials are synthesized and prepared by electrochemical deposition co-coating and one-step hydrothermal methods, respectively, and assembled into an asymmetric supercapacitor (ASC) device based on the two electrode materials. The study reveals that the surface capacitances of the positive and negative electrodes are 1685.5 mF cm-2 and 1134.98mFcm-2 correspondingly, with potential windows of both as high as 1.1V. Surprisingly, the potential window of the all-solid-state supercapacitor assembled based on the two electrodes reaches 2.2V, and the energy density reaches 0.44m W h cm-2, which is much higher than the performance indicators based on similar electrodes. The resulting excellent performance parameters are mainly attributed to the efficient synergy between the pseudo-capacitance effect of the MoO3 film and the high electrical conductivity of the Ti3C2Tx sheets, as well as the great improvement of the intrinsic electron mobility and ion diffusion channel stability of MnO2 by Mo and Al bimetallic doping.

Research on the Weldability and Service Performance of 7075 Aluminum Alloy Welding Wire Prepared by Spray Forming–Extrusion–Drawing

A large number of MIG welding tests were carried out on a 3 mm thick 7075 aluminum alloy plate prepared by the self-developed jet forming–extrusion–drawing process of 7075 high-strength aluminum alloy welding wire, and the welding process of the welding wire and the change in the performance of the welded joint after T6 heat treatment were studied. The results show that the self-developed wire has a good forming joint and a wide welding process window: the welding speed is 5–7 mm/s, and the welding current is 100–150 A. The main precipitated phases in the joint were η(MgZn2), S(CuMgAl2), Mg2Si, and Al13Fe4, which were continuously distributed at the grain boundaries in the form of coarse networks or long strips, which was an important reason for the weak performance of the joints. After the heat treatment of T6, the precipitated phase in the joint was greatly reduced, the element segregation phenomenon was improved, and the residual precipitated phase was mainly Al13Fe4 and a small amount of insoluble phase Fe and Si, and the recrystallization size of the heat-affected zone was refined. Through heat treatment, the average microhardness of the joint was increased from 110 HV to 150.24 HV, and the tensile strength was increased from 326 MPa to 536 MPa, reaching 97.5% of the strength of the base metal, indicating that the softening phenomenon was significantly improved after heat treatment, and the joint had excellent performance.

Interfacial properties of aqueous ionic liquids on graphene surface in supercapacitors

It is expected to improve the energy density of supercapacitors by applying ionic liquids (ILs) with wide voltage window as electrolyte and graphene high specific surface area as the electrode. Due to the hygroscopic nature of ILs, some water presenting in ILs electrolyte is found to be easy stacked near the positive electrode and effect the supercapacitors’ performance. In this work, acetonitrile (ACN) was taken to add into the ILs electrolyte to solve this problem, and the interfacial properties of aqueous ACN-ILs on charged graphene surface in supercapacitors was investigated from microscopic perspective. The effect of ACN content and charge density was also discussed. The results show that the addition of ACN not only increases the wettability of aqueous ILs on graphene surfaces, but also significantly inhibits the aggregation of water molecules on the positive electrode surface and reduces the aggregation degree of anions and cations in the electrolyte solution, particularly within hydrophilic ILs systems. In addition, cyclic voltammetry experiments confirmed that the electrochemical window of aqueous ILs was improved with addition of ACN. This study provides a significant foundation for further promoting the application of ILs as electrolyte in supercapatiors.

A theoretical study on the insights of designing and optimization of a CsSn(IxBr1-x)3 based solar cell

This work focuses on designing and optimizing a lead-free perovskite solar cell. The significance of band gap grading in obtaining better performance of the solar cell was studied in detail with CsSn(IxBr1-x)3 () being used as the active absorber material. The device showed a maximum power conversion efficiency (PCE) of when the interfacial defects were not considered. The optimum thickness was obtained to be 1 μm, and the corresponding doping concentration was 1020 cm-3. Further, a detailed discussion on the band diagrams, electric fields, and different recombination processes has been carried out in this work to get an idea about the varying PCE values at different operating conditions. The presence of Shockley-Read-Hall (SRH) recombination at various temperature values was observed, which partially contributed to the reduction in PCE values at higher temperatures. This work also discusses briefly about the probable losses involved with the device, which may be considered as the plausible reasons for obtaining PCE values less than the SQ limit. This information opens up a wide window for researchers to experimentally fabricate solar cells with proper cautions so that a device with PCE value exceeding Shockley Quisser (SQ) limit can be made available commercially.

Machine learning approaches to injury risk prediction in sport: a scoping review with evidence synthesis

ObjectiveThis study reviewed the current state of machine learning (ML) research for the prediction of sports-related injuries. It aimed to chart the various approaches used and assess their efficacy, considering...

Exploring the potential of 7,4′-di(diethylamino)flavylium as a novel photosensitizer for topical photodynamic therapy of skin cancer

Photodynamic therapy (PDT) is a minimally invasive therapeutic approach that has shown promising results in recent years, particularly in the dermatological clinical treatment of several pathologies, including neoplastic skin diseases. In light of the recent discovery of the photosensitizing properties of a water-soluble group of amino-based flavylium dyes, research efforts have led to the development of a novel synthetic dye with two diethylamino moieties in its structure, 7,4’-di(diethylamino)flavylium (7,4′diN(Et)2). This dye was tested as a potential photosensitizer for PDT of skin cancer. A single light dose of 22.5 J/cm2 efficiently killed SCC-25 (squamous cell carcinoma) and A375 (melanoma) cells, reducing cellular viability by more than 80% in the presence of the flavylium at 0.75 µM. Meanwhile, the negligible cellular toxicity of the dye in the absence of light stimulus points out a wide and safe therapeutic window. Interestingly, significant light-induced toxicity effects were still observed after washing out the compound before cell irradiation. Moreover, out of the three prototype flavylium-loaded hydrogels, each one based on a different polymer (Carbomer, Caesalpinia Spinosa Gum and Hydroxypropyl methyl cellulose), carbomer-based formulation stood out for its substantial absorbance and fluorescence increment and enhanced1O2 photogeneration activity compared to the flavylium in aqueous solution. The findings of this study provide valuable insights concerning the potential of this flavylium dye as a candidate for photodynamic therapy of skin cancer and strongly support the need for further testing in more advanced biological settings to fully assess its efficacy and safety.

High-Performance Flexible and Symmetric Supercapacitors Based on Micro-Flower-Like MnSe@Ti3C2Tx Heterostructure.

Flexible supercapacitors, renowned for their exceptional power density and cycling stability, are a focus in the field of energy storage. Ti3C2Tx MXene is a promising electrode material for supercapacitors owing to its excellent metallic conductivity. However, its stacking layered structure limits device performance on specific capacitance, operating voltage, and energy density. Herein, a MnSe@Ti3C2Tx heterostructure is developed to enhance the electrochemical performance of Ti3C2Tx-based electrode materials. With the solvothermal synthesis method, MnSe nanosheets are in situ grown on Ti3C2Tx surface to form micro-flower-like MnSe@Ti3C2Tx heterostructures by adjusting the ratio of ethanolamine solvent and the amount of Ti3C2Tx. The specific capacitance of the optimized heterostructure (E3/MnSe@Ti3C2Tx-45) is as high as 721.4Fg-1 at 1Ag-1, approximately ten times higher than that of pure Ti3C2Tx. The MnSe@Ti3C2Tx flexible symmetric supercapacitor (MT-FSC) based on E3/MnSe@Ti3C2Tx-45 exhibits a wide working voltage window of 1.2V and a large energy density of 28.68Whkg-1 at 308.23Wkg-1. The capacitance retention rate keeps 90.77% after 4000 charge-discharge cycles. Furthermore, MT-FSC can power LEDs even under large-angle (90°) bending. This heterostructure electrode material not only improves the electrochemical performance of Ti3C2Tx-based flexible supercapacitors but also offers a robust energy supply for flexible wearable electronic devices.

Tantalum pentoxide on a fused quartz substrate platform for advanced photonic integrated circuits

Integrated photonics is a growing field in optics and microelectronics. In particular, tantalum pentoxide (Ta2O5) is a promising material for advancing integrated photonic circuits. Ta2O5 exhibits favorable characteristics, such as a high refractive index, wide transparency window, and low autofluorescence. Therefore, this study develops low-loss Ta2O5 waveguide-based microring resonators optimized for telecom band operations on fused quartz substrates. The experiments demonstrated the excellent optical properties of Ta2O5 for fabricating high-performance photonic structures. Moreover, we explored integrating diamond-inverted nanocones with Ta2O5 waveguides for single-photon emission. The findings provide insights into using Ta2O5 to develop single-photon emitters integrated into photonic circuits.

Single photon scattering with the giant and small atom interplay in a one-dimensional coupled resonator waveguide

We study single photon scattering in a one-dimensional coupled resonator waveguide, which is dressed by a small and a giant artificial atom simultaneously. Here, we have set the small atom to be a neighbor to one leg of the giant atom, and the giant atom couples to the waveguide via two distant sites. When the small and giant atoms are both resonant with the bare resonator in the waveguide, we observe the perfect reflection of the resonant incident photon. On the other hand, when the small atom is detuned from the giant atom, the single photon reflection is characterized by a wide window and Fano line shape. We hope our work will pave the way for the potential application of small and giant atom hybrid systems in the study of photonic control in the low-dimensional waveguide structure.

Discovery of Novel PROTAC-Based HPK1 Degraders with High Potency and Selectivity for Cancer Immunotherapy.

Hematopoietic progenitor kinase 1 (HPK1, MAP4K1), a serine/threonine (SER/THR) kinase, has been identified as a negative immune regulator of T-cell receptor signaling. Deprivation of the HPK1 function suppresses tumor growth, providing an attractive strategy for cancer immunotherapy. Herein, we present a novel PROTAC-based HPK1 degrader compound DD205-291 with high selectivity and potency. DD205-291 showed a dose-dependent inhibition of SLP-76 phosphorylation and an induction of IL-2 and IFN-γ. Compared with other inhibitors, DD205-291 exhibited good efficacy and a favorable safety profile in the MC38 model. Specifically, oral administration of DD205-291 at 0.5 mg/kg in combination with anti-PD1 resulted in significant suppression with a TGI value of 91.0%. Furthermore, DD205-291 exhibited a low risk of cardiotoxicity and a wide safety window. This research effort demonstrates that DD205-291 is a promising preclinical candidate (PCC) for potential mono- and comboimmunotherapy of cancer.

Hydrangea-like MnO2@sulfur-doped porous carbon spheres with high packing density for high-performance supercapacitor

The high packing density of electrode materials is crucial for the miniaturization and lightweighting of energy storage devices. Nevertheless, a structural contradiction among high packing densities, sufficient ion, and electron transport channels is a challenge. In this research, a unique hydrangea-like compose (MnO2@S-PCS-5) is synthetized by a convenient and environmentally friendly method. The composite comprises a spherical carbon material matrix and MnO2 nanosheets, resulting in a high packing density of 1.79 g cm−3. Furthermore, the hydrangea-like structure exhibits a high number of active sites, facilitating ion transport and exhibiting excellent specific capacitance (Cv: 328.7 F cm−3). The asymmetric supercapacitors (MnO2@S-PCS-5//YP-50) exhibit a maximum energy density of 38.4 Wh kg−1 at a power density of 500 W kg−1, with a wide voltage window of 2.0 V. The results demonstrate densification is important for miniaturization of energy storage devices.

Boosting the phosphorus uptake of La2(CO3)3·8H2O based adsorbents via sodium addition: Relationship between crystal structure and adsorption capacity

Excess phosphate contents in water bodies triggers eutrophication, which posts significant challenges to the aquatic ecosystem. Lanthanum-carbonate based adsorbents exhibit excellent phosphate binding properties for remediating eutrophication. However, they suffer from significant adsorption-capacity loss (>85 %) at high pH. Little has been done on understanding this behavior for improving the phosphorus adsorption of lanthanum-carbonate adsorbents in alkaline environments (e.g. eutrophic water bodies). Here, we discover that La2(CO3)3·8H2O, when produced by a conversion reaction from NaLa(CO3)2·xH2O, exhibits high phosphate adsorption capacity in a wide pH window. Under alkaline conditions (e.g. pH = 10), its adsorption capacity decreases by only 8 % compared to the value under neutral pH. By isolating three different lanthanum-carbonate based compounds and analyzing their molecular structures, we find that the trace amount of Na+ residual in our La2(CO3)3·8H2O alters the chemical environment surrounding the La3+ ions, which may significantly boost the phosphate uptake at high pH. Our results provide molecular insights for further tuning the material structure of phosphate adsorbents to achieve robust performances.

Dynamically Confined Active Silver Nanoclusters with Ultrawide Operating Temperature Window in CO oxidation.

Supported metal nanoclusters are often highly active in many catalytic reactions but less stable particularly under harsh reaction conditions. Here, we demonstrate that this activity-stability trade-off can be efficiently broken through rational design of surrounding microenvironment of the supported nanocatalyst including gas adsorbate overlayer and underneath support surface chemistry. Our studies reveal that chemisorbed oxygen species on Ag surface and surface hydroxyl groups on oxide support, which are dynamically consumed during reaction but sustained by reaction environment (O2 and H2O vapor), drive spontaneous redispersion of Ag particles and stabilization of highly active Ag nanoclusters. Such a dynamic confinement effect from gas-catalyst-support interaction enables the Ag nanoclusters to exhibit complete catalytic oxidation of CO over a wide temperature window of 25 - 500 °C under dry conditions and 200 - 800 °C under wet conditions as well as remarkable stability at 300 °C over 1000 h.

Dynamically Confined Active Silver Nanoclusters with Ultrawide Operating Temperature Window in CO oxidation

AbstractSupported metal nanoclusters are often highly active in many catalytic reactions but less stable particularly under harsh reaction conditions. Here, we demonstrate that this activity‐stability trade‐off can be efficiently broken through rational design of surrounding microenvironment of the supported nanocatalyst including gas adsorbate overlayer and underneath support surface chemistry. Our studies reveal that chemisorbed oxygen species on Ag surface and surface hydroxyl groups on oxide support, which are dynamically consumed during reaction but sustained by reaction environment (O2 and H2O vapor), drive spontaneous redispersion of Ag particles and stabilization of highly active Ag nanoclusters. Such a dynamic confinement effect from gas‐catalyst‐support interaction enables the Ag nanoclusters to exhibit complete catalytic oxidation of CO over a wide temperature window of 25‐500 °C under dry conditions and 200‐800 °C under wet conditions as well as remarkable stability at 300 °C over 1000 h.

Linear and nonlinear optical properties of femtosecond laser inscribed waveguides into GLS glass

Gallium lanthanum sulfide (GLS) glass is a promising material for mid-infrared photonics due to its wide transmission window and its high nonlinear refractive index that is almost three orders of magnitude higher than that of fused silica. In this paper, we present the results of a detailed study into the linear and nonlinear optical properties of waveguides fabricated in GLS glass via ultrafast laser direct-inscription using three different techniques: cumulative heating in the thermal regime as well as multi-scan and half-scan in the athermal regime. Using quadriwave lateral shearing interferometry, we fully characterized the refractive index profiles of such inscribed waveguides and found no difference between half-scan and multi-scan writing which indicates the absence of laser-induced stress in this soft glass in stark contrast to fused silica. In terms of nonlinearity, we utilized self-phase modulation (SPM)-induced spectral broadening experiments at mid-IR wavelengths to demonstrate that waveguides fabricated in the athermal regime preserve the high intrinsic nonlinearity of the GLS bulk material, outperforming those written in the thermal regime based. These findings pave the way for the fabrication of fiber-coupled optical waveguide chips for nonlinear mid-infrared photonics.

A novel bio-based autocatalytic amide-type phthalonitrile monomer: Synthesis, curing kinetics and thermal properties

A bio-based bisphenol compound (DFA) was prepared using bisphenolic acid and furfurylamine in biomass as raw materials. Then, a bio-based amide phthalonitrile monomer (DFAP) was obtained in an environmentally friendly solvent. Nuclear magnetic resonance and Fourier transform infrared spectroscopy (FT-IR) proved the successful synthesis of DFA and DFAP. The curing behavior and curing kinetics of the polymer were studied using FT-IR and differential scanning calorimetry. Calculate the activation energy using the isoconversion method. The SB(m, n) autocatalytic reaction model describing the curing process of poly(DFAP) was modified and fitted by introducing the variable activation energy model. The thermal stability, thermomechanical properties and processing properties of the resin were studied using technologies such as thermogravimetric analyzer, dynamic mechanical analyzer and rheometer. The results show that the prepolymer has a wide processing window and a low melt viscosity. Poly(DFAP) has a high glass transition temperature and excellent thermal stability.

Advanced materials and fabricating approaches for proton exchange membrane fuel cells

AbstractProduction of electrical energy in an environmental‐friendly manner is important for meeting the increasing demand of electricity in smart vehicles and energy devices. Benefitted from its moderate working temperatures and high conversion efficiency, proton exchange membrane fuel cell (PEMFC) has received broad attention and commercialized rapidly in the past decades. Herein, we comprehensively review the advanced types of electrolytes and their underlying working mechanisms to offer a considerate guidance to develop novel electrolytes with high proton conductivity and wide working temperature window. Moreover, to rationally design cost‐effective and robust electrodes, the well‐developed anode and cathode and their fundamental working principles are elaborately reviewed and discussed. Furthermore, from the viewpoint of overall structure, fabricating approaches of functional components of PEMFC and their corresponding influencing factors are minutely reviewed and analyzed with the aim of tuning cell performance and preparing PEMFC in a high‐throughput way. Lastly, we highlight the conclusions of this review and present the penitential developing directions.

Solvent-free mechanochemical synthesis of Mg-gallic acid complex for the fabrication of high-performance supercapacitor porous carbon

At molecular level, it is challenging to construct a porous carbon from magnesium based template and low cost precursor by a facile route for supercapacitive energy storage, e.g. solvent-free approach because the coordination of magnesium ion with organic ligands usually needs participation of solvent. Herein, a balling milling mediated coordination of magnesium acetate and gallic acid was developed in the absence of solvent to prepare porous carbon. The key of the present strategy lies in the generation of volatile HAc, orienting the reaction in a favorable direction for the formation of complexes. The resultant porous carbon (denoted BGMC) owns a high microporostiy ratio (24.2 % vs template-free derived ones of 11.1 %), open accessed microstructure and hydrophobic character. As electrode for supercapacitor, in aqueous electrolyte, the BGMC based supercapacitor achieves a high energy density of 19.2 Wh kg−1@900 W kg−1, while, in organic electrolyte of 1.0 M TEABF4/AN, the symmetric device based on BGMC delivers energy in a wide voltage window of 0–3.5 V with large energy of 34.4 Wh kg−1@1750 W kg−1, which is superior to those of recently reported carbon based devices. And more, at high current density of 10 A g−1, the BGMC device can resist continual charge/discharge for 30 000 cycles, showing an excellent cycling stability. Our strategy involving solvent-freely coordination of template and precursor molecule to prepare porous carbon open up a route with facile, scalable and easy-operable attributes towards the preparation of functional porous carbon.

Co-calcination to produce a synergistic blend of bauxite residue and low-grade kaolinitic clay for use as a supplementary cementitious material

New sources of reactive supplementary cementitious materials (SCMs) are essential to help the cement industry to further lower CO2 emissions. A co-calcination process in which bauxite residue (BR) is mixed with kaolinitic clay before calcination can deliver such SCM. The main novelty of the work discussed here is that acceptable reactivity as a SCM can be reached when co-calcining the BR with clays having only 40 wt% of kaolinite. The use of such low-grade kaolinitic clay greater increases the process economics and therefore likely increases overall feasibility. A high inherent reactivity of the desilication products present in the BR is the cause of this ability of using low-grade kaolinitic clays. Cement mortars were made with 30 wt% replacement of CEM I, which showed adequate strength at 28 days and increased strength in comparison with calcined clays or other SCMs in the literature at early age (2–7 days). A wide process temperature window with relatively constant reactivity was observed, but a range of 700–750 °C is recommended for process stability. In addition, a life-cycle assessment underlines that at these conditions a sufficiently low embodied CO2 relative to Portland clinker production is obtained.

Observation of Temperature Dependent Atomic Off‐Centering in High Entropy Cubic I‐V‐VI2/IV‐VI Alloys with Ultralow Thermal Conductivity

AbstractI‐V‐VI2/IV‐VI compounds and their alloys are of great interest in the field of thermoelectricity due to their unique high‐symmetry crystal structures and unexpectedly low thermal conductivity, which is closely related to the off‐centering effect in the cubic lattice. However, the influence of such an effect on thermal transport across different temperatures remains largely elusive. Herein, using in situ pair distribution function analysis, it is directly observed that the sustained low thermal conductivity in n‐type (AgBiSe2)1‐x(PbS)x alloys stem from the dynamic intelligent switching of local structural distortions over wide temperature windows for the first time. Under ambient conditions, the local off‐centering of central atoms dominates the phonon scattering, while at high temperatures, the geometrical configuration of the ligands predominantly modulates thermal conductivity due to lattice expansion and diminished cation off‐centering. The complementary synergistic effect leads to an ultralow thermal conductivity (<0.64 W m−1 K−1) for (AgBiSe2)0.65(PbS)0.35 across the entire working temperature range and yields a lattice thermal conductivity of only 0.33 W m−1 K−1 at 800 K approaching the glass limit. Atomic‐scale insights into the thermal conductivity mechanism of I‐V‐VI2/IV‐VI alloys provide important guidance for designing high‐efficiency thermoelectric materials over broad operational temperature ranges.