High Power Stability Research Articles

Generation of sub-100 fs vortices from a Kerr-lens mode-locked Hermite-Gaussian Yb:CALGO oscillator.

Mode-locked oscillators with high-order transverse modes are excellent platforms for generating femtosecond optical vortices with high average power and good propagation stability. These have important applications in diverse fields such as optical communication, strong-field physics, and laser processing. So far, generating vortex pulses with ultrashort pulse duration remains a challenge. In this Letter, we report a Kerr-lens mode-locked Yb:CALGO laser oscillator delivering Hermite-Gaussian (HG) pulses with a pulse duration of 86 fs using a non-collinear pumping technique. 91 fs optical vortex pulses were generated by using a cylindrical-lens mode converter. To the best of our knowledge, this is the shortest pulse duration ever obtained from a diode pumped solid-state mode-locked oscillator with a pure high-order Hermite-Gaussian mode. The phase structures of the generated femtosecond vortices are characterized.

Electrogenic performance and carbon sequestration potential of biophotovoltaics.

Biophotovoltaics (BPV) is a clean and sustainable solar energy generation technology that operates by utilizing photosynthetic autotrophic microorganisms to capture light energy and generate electricity. However, a major challenge faced by BPV systems is the relatively low electron transfer efficiency from the photosystem to the extracellular electrode, which limits its electrical output. Additionally, the transfer mechanisms of photosynthetic microorganism metabolites in the entire system are still not fully clear. In response to this, this article briefly introduces the basic BPV principles, reviews its development history, and summarizes measures to optimize its electrogenic efficiency. Furthermore, recent studies have found that constructing photosynthetic-electrogenic microbial consortia can achieve high power density and stability in BPV systems. Therefore, the article discusses the potential application of constructing photosynthetic-electrogenic microbial aggregates in BPV systems. Since photosynthetic-electrogenic microbial communities can also exist in natural ecosystems, their potential contribution to the carbon cycle is worth further attention.

Vanadium Aluminium Carbide Saturable Absorber in Passively Q-switched Erbium-doped Fibre Laser

Following the success of graphene saturable absorber (SA) in the development of passively Q-switched fibre lasers within the past decade, research on two-dimensional (2-D) nanomaterials SAs have shown a significant rise in demands. Nonetheless, there have been several unavoidable setbacks due to the nature of certain nanomaterials, in terms of optical, electronic and physical properties up until the reveal of transition metal carbide (MXene) nanomaterials. These metal-ceramic materials exhibit excellent optical and electrical properties as well as outstanding physical characteristics. However, their synthesis processes involve hazardous and highly acidic chemicals, which drove the researchers to adopt their precursors— ternary nanolaminate carbides (MAX phases) nanomaterials with a simpler and more exquisite fabrication process. This paper presents a passively Q-switched erbium-doped fibre laser (EDFL) with the utilisation of a MAX phases nanomaterial, vanadium aluminium carbide (V4AlC3) as SA. The V4AlC3 SA was fabricated through the solution casting technique with polyvinyl alcohol as the host polymer. The V4AlC3 SA was then integrated into a passively Q-switched EDFL configuration. The performance of V4AlC3 SA as a Q-switcher was determined with the assistance of an optical spectrum analyser (OSA), mixed domain oscilloscope (MDO), and optical power meter (OPM). The maximum pulse repetition rate and minimum pulse width were 54.37 kHz and 6.43 ms, respectively. The minimum repetition interval was 18.33 ms and the duty cycle was 0.326. The highest attained output power was 2.5 mW. Through calculation, the maximum pulse energy and peak power were identified as 45.246 nJ and 6.602 mW. The extensively gigantic pulses in nanosecond duration at 1560.16 nm was accomplished by the V4AlC3 SA, thus proving its stability which also signifies good applications especially those acquiring stable high power and energy.

A Hybrid Biofuel Cell with High Power and Operational Stability Using Electron Transfer‐Intensified Mediators and Multi‐Interaction Assembly

AbstractBiofuel cells (BFCs) offer an eco‐friendly route to convert biochemical energy into electricity. However, their performance is hindered by insufficient enzyme immobilization as well as limited electron transfer within the enzymatic electrode. While the incorporation of redox mediators (RMs) into enzyme layers has been shown to improve BFC performance through enhanced electron transfer, progress has plateaued in the last decade. Herein, a major breakthrough is presented realized by a novel strategy that exploits electron transfer‐intensified RM layers. Metal nanoparticles covalently bridged between neighboring RMs facilitate electron transfer ubiquitously. Electron transfer characteristics are enhanced not only within the RM layers themselves, but also at the glucose oxidase (GOx)/host electrode and GOx/GOx interfaces. This leads to a remarkable performance boost in the enzymatic anode. A hybrid BFC constructed with innovative anode and Pt‐based cathode exhibits a striking combination of high power output (2.3 and 8.5 mW cm−2 at 10 and 300 mmol L−1 glucose, respectively) and exceptional operational stability (≈80% and 47% power retention after 10 days and 1 month, respectively), outperforming all previously reported BFCs by a significant margin.

Exploring the Synergistic Potential of Bimetallic Sulfide (SrCuS) as Battery‐Grade Electrode Material for Hybrid Supercapacitor Applications

State‐of‐the art hybrid energy storage devices, owing to their attractive electrochemical features of high specific energy, power, and great stability, have earned incredible attention throughout the world. Herein, bimetallic sulfide (SrCuS) composites with different concentration are electrochemically analyzed for hybrid supercapacitor applications. In half‐cell assembly, amidst all compositions, Sr0.5Cu0.5S reveals relatively better performance demonstrating specific capacity “Qs” of 596.48 C g−1. To assess the hybrid device's (Sr0.5Cu0.5S//AC) electrochemical performance, positive electrode (Sr0.5Cu0.5S) along with activated carbon as negative electrode is utilized. The device displayed energy density “Ed” of (51.28 W h kg−1) and power density “‘Pd” of 6800 W kg−1. Furthermore, the device is examined for capacitive‐ and diffusive‐controlled processes employing a semi‐empirical approach, using linear and quadratic models, respectively.

Enhanced bifunctional oxygen electrochemical catalytic performance using La-doped CoFe2O4 spinel supported by 3D-G for Zn-air batteries

The preparation of bifunctional catalysts for oxygen reduction (ORR) and oxygen evolution (OER) is crucial for Zn-air batteries. Here, we report a La doped CoFe2O4 spinel catalyst supported on three-dimensional graphene (3D-G), where La can facilitate electron transfer from Co to Fe, leading to increased electron cloud density in Fe and improved catalytic performance. The redshift of the G peak in the Raman spectra indicates the interaction between the π bond of 3D-G and d orbitals in La0.2CoFe1.8O4. La0.2CoFe1.8/3D-G exhibits superior ORR performance (E1/2 = 0.86 V vs. RHE) and OER performance (Ej=10 = 1.55 V vs. RHE) to CoFe2O4/3D-G (E1/2 = 0.831 V vs. RHE, Ej=10 = 1.603 V vs. RHE). Furthermore, it demonstrates excellent bifunctional oxygen catalytic performance while maintaining high power density and stability in liquid zinc-air batteries (ZABs) and flexible ZABs (F-ZABs). This work presents a viable strategy for utilizing rare earth element doped spinels to enhance oxygen catalyst and ZABs performance.

Synthesis Processes of Carbonaceous Material/Conducting Polymer Nanocomposites in Relation to Grafting and Electrochemical Properties for Supercapacitor Application: A Review

Supercapacitors are the energy storage devices that have gained increased attention due to high charge storage capacity, fast charge-discharge rate, high specific power and excellent cycle stability. Recently, research on supercapacitors is focused on the development of new electrode materials prepared by surface engineering to obtain superior electrochemical performance. Carbonaceous materials (CM) such as graphene, graphene oxide (GO), reduced graphene oxide (rGO) and carbon nanotubes (CNTs) etc. and conducting polymer (CP) based composite materials have gained increased attention for their use in supercapacitors. The nanocomposites obtained by merely mixing these two components pose some serious drawbacks such as low conductivity or poor film forming ability. The conjugation of CPs to CMs through covalent bonds is able to address these drawbacks. This review mainly provide collective information about various synthetic strategies to obtain CP grafted CMs for supercapacitor application. Herein, we provide information on different CP-CM conjugation reactions for obtaining the composites and their effects on electrochemical performances. The analysis revealed the importance of CP-CM grafting is important for tuning the electrochemical properties of the materials.

High Power and High Stability 13.5 nm Extreme Ultraviolet Light Source Driven by High‑Order Harmonics

High Power and High Stability 13.5 nm Extreme Ultraviolet Light Source Driven by High‑Order Harmonics

Achieving high power density and stability in aqueous Mg–air batteries using taurine electrolyte additives

Aqueous Mg–air batteries are promising candidates for large-scale energy storage, but their practical application is significantly hindered by water-induced parasitic reactions and the chunk effect.

Photo-nanozyme Coupling Catalyzes Glucose Oxidation for High-performance Enzymatic Biofuel Cells

Glucose biofuel cells (GBFCs) are special energy conversion devices using naturally abundant glucose as fuel. However, achieving high power output and stability remains a challenge in existing GBFC. In this...

Interfacial Electrochemical Polymerization of PEDOT@Polyoxometalates Thin Films As Electroactive Material for Energy Storage Devices

The urgent need for a decarbonized power sector has been one of the most important motivations to get a full transition from the fossil-fuel energy sources to a sustainable energy future based on renewable energy alternatives. In this regard, energy conversion and storage devices, such as batteries, fuel cells and supercapacitors, play a key role in supplying steady power and energy densities in order to guarantee the current energy demand [1]. Among the different alternatives, the design and synthesis of advanced functional nanostructured materials provide an important route to obtain efficient energy devices with high power densities, stability and remarkable energy densities [2].Conducting polymers (CP) have been extensively exploited in a wide application range as result of their remarkable charge-mobility, electrical conductivity, and the scalable synthesis processes. Additionally, the storage of charge, which occurs by a doping process, has been ideal for application as electrochemical supercapacitors [3]. In addition, the CPs network have provided an interesting electrode material in which other active materials (i.e., graphene, MOF) and redox species can be incorporated to induce additional pseudocapacitive processes in the electrode, enhancing the charge stored. The polyoxometalates (POMs), inorganic heteropolyanions received great attention due to their multielectron redox processes in aqueous media [4].Herein, we have explored the electrosynthesis of composite materials based on PEDOT and polyoxometalates (POMs) employing the electrochemical polymerization at a polarized organic | aqueous liquid | liquid interface (L|L), in which the POM acts as oxidizing agent of EDOT and electroactive specie incorporated in the polymer chain network as dopant. The polymerization process was based on the ion migration-controlled by the potential biasing of the water-oil interface. The resulting thin films show the presence of Mo and W within the polymer as well as the presence of different redox processes associated with the POM incorporated in the PEDOT. The induced pseudocapacitive processes in the composite materials have shown high stability in acid media, making it a good candidate as an electrode material in symmetric supercapacitors.

Tribological Performance and Scuffing Resistance of Cast-Iron Cylinder Liners and Al-Si Alloy Cylinder Liners

In order to better determine the applicable working conditions of Al-Si alloy cylinder liners and cast-iron cylinder liners, their tribological performance and scuffing resistance are discussed in this paper. After wear and scuffing tests, it was found that cast-iron cylinder liners had better wear resistance and better scuffing resistance, but poor friction performance. Al-Si alloy cylinder liners had weaker wear resistance and scuffing resistance, but excellent friction performance. The wear mechanism of cast-iron cylinder liners is slight adhesive wear, and they are suitable for traditional fuel engines and turbocharged engines with high load, high power, and high stability. The wear mechanism of Al-Si alloy cylinder liners was a mixture of adhesive wear and abrasive wear, and they are suitable for engines that are lightweight, efficient, and energy-saving, and operate at high speeds.

Extraction of Phosphorus from Sewage Sludge Ash—Influence of Process Variables on the Electrodialytic Process

Phosphorus is a critical, irreplaceable raw material, and developing methods to recover P from secondary sources such as sewage sludge ash (SSA) is crucial. Two-compartment electrodialytic extraction (2C-ED) is one method where an electric DC field is applied to extract P and separate heavy metals simultaneously. Several process parameters influence 2C-ED, and they influence each other mutually. This paper explores chemometrics modeling to give insight into the 2C-ED process and, specifically, optimization of the experimental parameters towards 80% P extraction. A projections-to-latent-structures model was constructed based on new 2C-ED experiments conducted with one SSA type. The model was stable (high correlation factor and predictive power). Variable importance in the projection (VIP) plots showed that the influence of the variables was in the order: current > duration > L:S ratio > stirring velocity > dispersion solution (weak acid or distilled water). Contour plots were used for exploring different P extraction strategies. For example, more P mass per unit current was extracted at an L:S ratio of 7 compared to L:S 14. This shows that treating a thicker SSA suspension is preferable to optimize the current efficiency. The chemometric model proved valuable for optimizing the 2C-ED process and future scale-up.

High stability and low noise laser-diode end-pumped Nd: YAG ceramic passively Q-switched laser at 1123 nm based on a Ti3C2T x -PVA saturable absorber

We report a high repetition frequency, high power stability and low laser noise laser-diode (LD) end-pumped Nd: YAG ceramic passively Q-switched laser at 1123 nm based on a Ti3C2T x -polyvinyl alcohol (PVA) film as a saturable absorber (SA). A Brewster polarizer (BP) and a birefringent crystal (BC) are incorporated to enable frequency selection and filtering for the passively Q-switched 1123 nm pulsed laser to improve the power stability and reduce the noise. When the pump power is 5.1 W, an average output power of 457.9 mW is obtained, corresponding to a repetition frequency of 1.09 MHz, a pulse width of 56 ns, a spectral line width of 0.65 nm, a power instability of ±0.92%, and a laser noise of 0.89%. The successful implementation of the “Ti3C2T x -PVA film passively Q-switching” combined with “frequency selection and filtering of BP + BC” technology path provides a valuable reference for developing pulsed laser with high repetition frequency, high stability and low noise.

Compact Q-switched Tm:YLF laser with high slope efficiency, high power stability and high beam quality

This paper presents a high-efficiency and actively Q-switched Tm:YLF laser with a compact design by arranging the optical elements closest to each other in a linear cavity. With a flat output coupler (OC), slope efficiency of 74.7% and output power of 12.41 W were achieved in continuous-wave operation. Using a volume Bragg grating (VBG) as the OC and wavelength selector, the output power and slope efficiency of the 1.908 μm laser were 10.65 W and 67.3%, respectively. The corresponding beam quality M2 was about 1.5 at the maximum power. The Tm:YLF laser with VBG revealed high stability with a power fluctuation of 0.45% and central wavelength variation of 0.23 nm for one-hour continuous testing. In pulsed operation at 10 kHz, average power of 10.07 W and slope efficiency of 66.0% were obtained. This actively Q-switched Tm:YLF laser of 10-W level will be an ideal pump source for compact and high-efficiency mid-infrared optical parametrical oscillators for practical applications.

Solubility of hesperidin drug in aqueous biodegradable acidic choline chloride-based deep eutectic solvents

Important efforts have been made over the past years to improve the drug acts, which leads to the discovery of novel drug preparations and delivery systems. The selection of suitable green solvents for novel drug discovery and drug delivery depends on a molecular-level understanding of the interaction between drug molecules and the solvents. Deep eutectic solvents (DESs) are already used in sustainable extraction methods of natural products for their very high solvent power, high chemical and thermal stability, non-toxicity, and non-flammable. The thermodynamic investigation provides deep and complete knowledge of interactions and the choice of appropriate and suitable production compounds in pharmaceutical fields. Particularly, the analysis of drugs+DESs in aqueous media is a central issue in many types of research. This research is aimed to determine hesperidin (HES) solubility in water and DES solvents [choline chloride/citric acid (ChCl/CA), choline chloride/oxalic acid (ChCl/OA), choline chloride/malonic acid (ChCl/MA), and choline chloride/lactic acid (ChCl/LA)] at temperature range (298.15–313.15 K). Furthermore, the measured solubility data of HES in studied aqueous DESs solutions was fitted by models of Van’t Hoff–Jouyban–Acree and Modified Apelblat–Jouyban–Acree. Finally, the Hansen solubility parameters as thermodynamic aspect for analyzing the dissolution processes for the four investigated aqueous DESs solutions were estimated.

Improvement of Hybrid Electrode Material Synthesis for Energy Accumulators Based on Carbon Nanotubes and Porous Structures.

Carbon materials are promising for use as electrodes for supercapacitors and lithium-ion batteries due to a number of properties, such as non-toxicity, high specific surface area, good electronic conductivity, chemical inertness, and a wide operating temperature range. Carbon-based electrodes, with their characteristic high specific power and good cyclic stability, can be used for a new generation of consumer electronics, biomedical devices and hybrid electric vehicles. However, most carbon materials, due to their low electrical conductivity and insufficient diffusion of electrolyte ions in complex micropores, have energy density limitations in these devices due to insufficient number of pores for electrolyte diffusion. This work focuses on the optimization of a hybrid material based on porous carbon and carbon nanotubes by mechanical mixing. The purpose of this work is to gain new knowledge about the effect of hybrid material composition on its specific capacitance. The material for the study is taken on the basis of porous carbon and carbon nanotubes. Electrodes made of this hybrid material were taken as an object of research. Porous carbon or nitrogen-containing porous carbon (combined with single-, double-, or multi-layer carbon nanotubes (single-layer carbon nanotubes, bilayer carbon nanotubes or multilayer carbon nanotubes) were used to create the hybrid material. The effect of catalytic chemical vapor deposition synthesis parameters, such as flow rate and methane-to-hydrogen ratio, as well as the type of catalytic system on the multilayer carbon nanotubes structure was investigated. Two types of catalysts based on Mo12O28 (μ2-OH)12{Co(H2O)3}4 were prepared for the synthesis of multilayer carbon nanotubes by precipitation and combustion. The resulting carbon materials were tested as electrodes for supercapacitors and lithium ion intercalation. Electrodes based on nitrogen-containing porous carbon/carbon nanotubes 95:5% were found to be the most efficient compared to nitrogen-doped porous carbon by 10%. Carbon nanotubes, bilayer carbon nanotubes and multilayer carbon nanotubes synthesized using the catalyst obtained by deposition were selected as additives for the hybrid material. The hybrid materials were obtained by mechanical mixing and dispersion in an aqueous solution followed by lyophilization to remove water. When optimizing the ratio of the hybrid material components, the most effective porous carbon:carbon nanotubes component ratio was determined.

Design a high-performance thermoelectric generator by analyzing industrial heat transfer

Industrial production will release a large amount of waste heat into the environment and cause serious energy waste. Currently, most waste heat recovery technologies cannot directly convert waste heat into energy required for industrial production, and there is a problem of low energy conversion efficiency problem. Thermoelectric conversion technology can convert industrial waste heat into electrical energy and directly use it in industrial production. This study uses a numerical method to analyze the heat transfer behavior between an industrial thermal environment and a thermoelectric generator (TEG). According to the numerical calculation results, the deficiencies of the original TEG are optimized, and a new TEG with high power generation performance and stability is designed. Finally, the accuracy of numerical calculation results and the industrial application feasibility of new TEG are verified through on-site tests. The results show that the power generation performance of the new TEG has been greatly improved, and it can operate stably for a long time in an industrial environment. The best economic benefit can be obtained by installing new TEGs in the x = 20 m-21 m, the power generation cost is 3.45$/W, and the total output power is 0.55 kW. The cost of power generation for new TEGs will increase as the installation area increases. When new TEGs are installed in the x = 20 m-24 m, the power generation cost is 3.97$/W, and the total output power is 1.96 kW. It can be known from the on-site testing results that the new TEG has high practical value and can be widely used in industrial waste heat recovery.

Frequency regulation of Terahertz quantum cascade lasers by changing barrier thickness

Terahertz (THz) sources with different frequency are important to gas detection. THz quantum cascade lasers (QCLs) based on resonant phonon structure with different frequency emission by changing transition barrier thickness are hereby presented. By theoretically calculation, a 0.19 nm thickening change of transition barrier would cause an approximately 350 GHz regulation range in frequency, and is then confirmed by experimental results. The corresponding far field beam profile keeps almost unchanged. With the increase of the transition barrier thickness, the output power only decreases by 15%, but the threshold current density decreases 24%. This simple method contributes to a satisfactory gas-detection approach with a stability of relative high output power.

Single-Phase H-Bridge Rectifier Fed High-Speed SRM System Based on Integrated Power Control

Traditionally, an uncontrollable diode bridge rectifier (DBR) is employed to supply the constant DC voltage for the asymmetric half-bridge (ASHB) converter fed switched reluctance motors (SRMs), which brings about inferior AC side power quality. In this article, a high-speed SRM drive system based on integrated power control scheme is proposed, which not only realizes the regulation of SRM but improves the AC side power quality. For the topology, a single-phase H-bridge rectifier and ASHB converter are connected in a cascade arrangement to form an AC-DC-DC converter to drive the SRM. For the control, the proposed integrated power control scheme governs the rectifier and SRM as one control unit in which stable motor speed and high AC side power factor are realized via regulating the input real and reactive power, respectively. Moreover, the proposed system has bi-directional power flow capability, which means the power can flow out of and into the AC side. Experiments are carried out to investigate the steady-state and dynamic performances of the proposed driving system. The experimental data and performance comparison confirm its effectiveness.