Specific Power Research Articles

Comparison of Preprocessing Method Impact on the Detection of Soldering Splashes Using Different YOLOv8 Versions

Quality inspection of electronic boards during the manufacturing process is a crucial step, especially in the case of specific and expensive power electronic modules. Soldering splash occurrence decreases the reliability and electric properties of final products. This paper aims to compare different YOLOv8 models (small, medium, and large) with the combination of basic image preprocessing techniques to achieve the best possible performance of the designed algorithm. As preprocessing methods, contrast-limited adaptive histogram equalization (CLAHE) and image color channel manipulation are used. The results show that a suitable combination of the YOLOv8 model and preprocessing methods leads to an increase in the recall parameter. In our inspection task, recall can be considered the most important metric. The results are supported by a standard two-way ANOVA test.

REDUCING THE VISCOSITY OF THE OIL MIXTURE BY A ROTARY PULSE APPARATUS IN UKHTA — YAROSLAVL OIL PIPELINE

Physical methods of exposure can be used to improve the rheological characteristics of viscous, resinous oils, the transportation of which through main pipelines requires additional operating costs. The authors of this article evaluated the effectiveness of the method for improving oil rheology due to multifactorial effects (shear loads, high–amplitude pressure pulses, developed turbulence) on a sample of a mixture of oils of the Ukhta - Yaroslavl oil pipeline in a rotary pulse apparatus (RIA). The specific power consumption for processing an oil sample was 2.84 kWh/m3. The initial rheological and physico-chemical parameters of the studied oil are described, according to which it is characterized as heavy, viscous, highly resinous oil. The analysis of the flow curves showed that, by the nature of the flow, the sample of a mixture of oils from the Ukhta — Yaroslavl main oil pipeline belongs to Newtonian liquids. The evaluation of the effectiveness of the multifactorial effect on the oil sample implemented in RIA was carried out using dimensionless coefficients showing the ratio of dynamic viscosity, the specific power required to maintain the flow of oil in a rotary viscometer before and after physical exposure to oil, as well as the ratio of the change in the energy of thixotropy of oil to the energy spent on the processing process. The samples were processed in an RIA-based installation, in which pressure pulsations, developed turbulence, and large shear loads are generated in the liquid flow. When comparing the viscosity values of untreated and treated mixed oil in a rotary pulse apparatus, the dynamic viscosity measured at 20 °C decreased by 8 %. The component composition of the oil after processing in RIA has practically not changed. Measuring the viscosity of oil before processing and immediately after processing in RIA shows a decrease in viscosity by more than two times, since the temperature of the oil flow increases after passing through RIA by more than 10 °C. The increase in oil temperature during processing is due to large shear stresses during its flow in slit channels and in the gap between the rotor and stator due to the large amplitude of pressure pulsations and flow velocity.The relaxation time of the rheological parameters of the treated oil was seven days.

Ru‐MnO Heterostructure Clusters Toward Efficient and CO‐Tolerant Alkaline Hydrogen Oxidation Reaction

AbstractDesigning efficient and CO‐tolerant catalysts for hydrogen oxidation reaction (HOR) in anode is one of the challenges for alkaline exchange membrane fuel cells in practical application. Herein, Ru‐MnO heterostructure with two adjacent clusters supported on commercial carbon (BP 2000) (denoted as Ru‐MnO/C) is designed to accelerate the sluggish kinetics of alkaline HOR. The cluster–cluster heterostructure interface modifies the electronic structure of Ru sites with electron transfer from Ru to MnO, then optimizes the adsorption of intermediates on Ru sites. Consequently, this catalyst exhibits high catalytic HOR activities in alkaline media with high exchange current density (3.71 mA cm−2) and mass activity (0.78 A mgRu−1). Meanwhile, the alkaline exchange membrane fuel cell delivers a specific peak power density (PPD) of 7.0 W mg−1Ru under H2/O2 condition, which is higher than that of most reported catalysts. More importantly, the catalyst also demonstrates the remarkable stability and CO‐tolerance. This work presents the superiority of cluster–cluster heterostructure interface toward efficient HOR, which is expected to further enlighten the design of advanced catalysts for electrocatalysis.

Characterising the power spectrum dynamics of the non-REM to REM sleep transition.

The transition from non-rapid eye movement (NREM) to rapid eye movement (REM) sleep is considered a transitional or intermediate stage (IS), characterised by high amplitude spindles in the frontal cortex and theta activity in the occipital cortex. Early reports in rats showed an IS lasting from 1 to 5 s, but recent studies suggested a longer duration of this stage of up to 20 s. To further characterise the IS, we analysed its spectral characteristics on electrocorticogram (ECoG) recordings of the olfactory bulb (OB), primary motor (M1), primary somatosensory (S1), and secondary visual cortex (V2) in 12 Wistar male adult rats. By comparing the IS with consolidated NREM/REM epochs, our results reveal that the IS has specific power spectral patterns that fall out of the NREM and REM sleep state power distribution. Specifically, the main findings were that sigma (11-16 Hz) power in OB, M1, S1, and V2 increased during the IS compared with NREM and REM sleep, which started first in the frontal part of the brain (OB -54 s, M1 -53 s) prior to the last spindle occurrence. The beta band (17-30 Hz) power showed a similar pattern to that of the sigma band, starting -54 s before the last spindle occurrence in the M1 cortex. Notably, sigma infraslow coupling (~0.02 Hz) increased during the IS but occurred at a slower frequency (~0.01 Hz) compared with NREM sleep. Thus, we argue that the NREM to REM transition contains its own local spectral profile, in accordance with previous reports, and is more extended than described previously.

PD-Free Design of Insulation Systems: An Application to Laminated Busbars

The reliability of components of industrial electrical assets fed by power electronics might be at risk due to the type and extent of electrothermal stresses. The move of power electronics toward higher levels of voltage, switching frequency, slew rate, and specific power increases the risk of partial discharge inception and thus of accelerated extrinsic aging and premature failure. The reaction to this challenge is to embrace the concept of partial discharge-free (PD-free) design and operation. This paper presents a PD-free approach to the design of laminated busbars, considering both AC and DC insulation subsystems, and focusing on surface insulation. The availability of a recently proposed model to estimate the inception field is a key tool. The model is validated through PD measurements performed on a laminated busbar, using new automatic software that can identify the type of source generating PD. Combined with electric field calculations, the model provides estimates of the PD inception voltage which are almost coincident with the measurement results. Inception voltages in the order of 10 kV and 20 kV have been observed for AC and DC excitation, respectively. In the case of DC supply, tests at different ambient temperatures, 25 °C and 60 °C, indicate that the inception voltage does not change significantly with temperature. Disposability, scalability to any voltage/power, and capability to work, potentially, for any other type of insulation system, are interesting features of the proposed approach, which are discussed in the paper.

Ternary MXene/PANI/ZnO-based composite with a built-in p–n heterojunction for high-performance supercapacitor applications

Abstract Two-dimensional (2D) Ti3C2T x MXene-based materials have attracted widespread attraction in the field of energy storage owing to their high conductivity and accordion-like structure. However, challenges such as restacking and oxidative degradation of the Ti3C2T x MXene structure lead to poor stability, low conductivity, low specific capacitance and, consequently, a low specific energy, hindering their extensive adoption at an industrial scale. In this study, a ternary MXene/polyaniline (PANI)/ZnO (MPZ) composite has been synthesized via surface engineering of two-dimensional (2D) MXene using one-dimensional (1D) PANI nanowires and ZnO nanoparticles to enhance its specific energy and stability while sustaining its specific power. 1D PANI nanowires and ZnO nanoparticles act as spacers to prevent restacking, while also exposing the suppressed redox active sites of 2D MXene and preventing it from being oxidized by forming a porous conductive network all over the surface of the MXene. PANI and ZnO also provide additional electroactive redox sites by forming p–n heterojunctions, thus enhancing faradaic redox reactions and the specific capacitance of the MPZ composite. As a result, the overall electrochemical performance and stability of the ternary MPZ composite are enhanced due to the synergistic interactions among the individual components within the ternary MPZ composite. At a low current density of 0.1 A g−1, the ternary MPZ composite exhibited a maximum specific capacitance of 651.96 F g−1 and a highest specific energy of 32.59 Wh Kg−1 while maintaining a specific power of 60 W Kg−1 as compared to MXene and binary MP composite. Furthermore, it showcased exceptional cyclic stability over 10 000 cycles with 94.75% and 92.95% capacitive retention at 0.6 A g−1 current density and 40 mV s−1 scan rate, respectively. Thus, this current study highlights an effective strategy to enhance the specific energy of MXene-based supercapacitors through surface engineering and the construction of p–n heterojunctions within the composite.

High-performance, high energy density symmetric supercapacitors based on δ-MnO2 nanoflower electrodes incorporated with an ion-conducting polymer.

The present work investigates liquid-based and liquid-free supercapacitors assembled using δ-MnO2-nanoflower-based electrodes. An optimized electrode composition was prepared using acetylene black (AB), a polymer (PEO), a salt (LiClO4), and δ-MnO2 and used for device fabrication. The composite electrode was tested against a liquid electrolyte and a 'liquid-free' composite solid polymer electrolyte (CSPE) membrane. In a three electrode geometry, with 1 M solution of LiClO4 as an electrolyte, the specific capacitance of the electrode was found to be ∼385 F g-1, with a specific energy of ∼23 W h kg-1 and specific power of ∼341 W kg-1 (at 1 mA, 1 V). Dunn's method confirmed that the charge storage process was predominantly pseudocapacitive. When the device was assembled in a two-electrode Swagelok cell, a stable specific capacitance of ∼216 F g-1 was observed with a specific energy of 30 W h kg-1 and a specific power of 417 W kg-1. The supercapacitors exhibited stable performance up to ∼7000 cycles with ∼90% capacitance retention and ∼97% coulombic efficiency. A combination of these cells could light two white light-emitting diodes (LEDs, 3 V) for at least ∼10 minutes. Further, all-solid-state supercapacitors (ASSCs) were fabricated using a Li+ ion (CSPE) membrane. The ASSCs exhibited a specific capacitance of ∼496 F g-1 after ∼500 cycles, with a specific energy and power of ∼19 W h kg-1 and ∼367 W kg-1, respectively. The investigation reveals that the electrodes are versatile and show compatibility with liquid and solid electrolytes. The polymer in the electrode matrix plays an important role in enhancing device performance.

Thermodynamic Modelling of a Twin-Stage Claw Vacuum Pump and Its Gas Pressurization Analysis

Multi-stage claw vacuum pumps are crucial in various industrial applications for efficiently achieving high vacuum levels compared to other positive displacement vacuum pumps. In order to elucidate the gas pressurization process of the multi-stage claw vacuum pump and clarify its structural design principles, the authors investigated a twin-stage claw vacuum pump as the main research subject, and analyzed its working characteristic. A thermodynamic model of the twin-stage claw vacuum pump describing the pressurization process was established, and the results were verified by means of experiments. Moreover, effects of the phase difference φⅠ-Ⅱ, the first-stage discharge port angle θd,Ⅰ and the thickness ratio B1:B2 on pump performance were discussed. Results show that as φⅠ-Ⅱ increases, the pump power of the first stage gradually increases, while the power of the second stage decreases and then increases. With the increase of θd,Ⅰ, the pump power decreases and then increases. When the suction pressure is 10kPa, the specific power reaches its minimum value under B1: B2=2:1. As the suction pressure increases, the pump power gradually increases, and its specific power fells substantially and then levels out. These contents are of great significance for the design and optimization of multi-stage claw vacuum pumps.

Morphological impact on the supercapacitive performance of nanostructured ZnO electrodes

This study investigated the influence of the ZnO morphology on the energy storage capacity of symmetric supercapacitor devices, focusing on the defect centers present in the materials due to morpho-structural differences. Thus, ZnOs with five different morphologies were synthesized with varying methods in which the nanoparticles have the form of flowers, bullets, pyramids, hexagons, and rods. All materials were thoroughly characterized by scanning/transmission electron microscopy, X-ray diffraction, and spectroscopic techniques like photoluminescence, UV–Vis, Raman, and electron paramagnetic resonance spectroscopy. Subsequently, the ZnO-based materials were assembled in symmetric supercapacitor devices to test their energy storage capabilities. The ZnO with nanorod and hexagonal morphologies showed the best specific capacity (180 and 142 F/g), energy density (25 and 19 Wh/kg), and power density (211 and 252 kW/kg) values. The importance of the defect centers in the materials was highlighted, where the ratio between the Zn and O vacancies, evidenced by EPR spectroscopy, plays a crucial role in the ZnO materials’ energy storage capacity. The Raman results support the proposed model, which underlines the importance of oxygen vacancies. In contrast, BET measurements show that the specific surface area of the morphologically distinct ZnO materials does not change drastically, validating the importance of the defect centers in the materials. A so-called “bottle-neck” effect is proposed to describe the relation between the paramagnetic vacancies and the electric properties of the materials.

Measurements of microwave transmission mode in HL-3 tokamak relevant ECH corrugated waveguides transmission line

The transmission modes of high-power millimeter wave in corrugated waveguides transmission line (TL) are crucial, especially for the long-pulse operation for long-distance TL. The microwave transmission mode in the TL on HL-3 tokamak relevant the electron cyclotron heating system are studied for the purpose according to the phase retrieval method based on intensity distribution measured by an infrared camera at several different locations away from the outlet of TL. A specific high power test platform with about 40-meter TL is established and the mode contents in the middle and the end of the TL are analyzed. In the middle of the TL, the proportion of main transmission mode LP01 mode is about 97% and other high-order modes contents are less than 3%. In the end of the TL, the main mode purity is about 94%, and the high-order mode, LP11 even mode is excited about 4.6%. These mode analysis results indicate that the high-power and long-pulse millimeter wave corrugated waveguides TL are designed and machined well, and the alignment method for long distance transmission line installation is highly useful for high-purity wave mode transmission.

Visible-light-operative photocatalyst based on Er-TiO2 Nanostructures Blended with Room temperature ferromagnetism, band-gap Increment, and high optical transparency

TiO2 thin films doped with Er+3 percentage (1-5wt.%) have been prepared using the sol-gel dip coating technique. Er influences the morphological, structural, magnetic, electrochemical, UV, dielectric, Photoluminescence, and photocatalytic properties of TiO2. FTIR was utilized to examine the different functional groups. The confirmation of the anatase phase formation was established through XRD spectra and FTIR spectra. When the concentration of dopant increased, the crystallite size was found to be decreased from 7.96 to 5.62 nm. A blue shift was noticed in transmission spectra as the dopant concentration increased leading to an increase in the bandgap of thin films. The dielectric properties of all thin films exhibited typical behavior. The barrier height, density of localized states at fermi levels, and hopping distance were examined using AC conductivity measurements. As dopant concentrations increased the dielectric constant increased while AC conductivity decreased. The outcomes of electrochemical charge-discharge tests provided the specific capacitance, power density, and Energy of Er-doped TiO2. Er-doped TiO2 especially at 5wt.% showed significant photocatalytic activity in decomposing indigo carmine under sunlight, suggesting its potential for water treatment, and mitigating environmental pollution. Furthermore, Er-doped TiO2 demonstrated efficient functionality as a CO gas sensor. Er-doped TiO2 exhibited violet photoluminescence, with emission intensity modulated by elevating the Er percentage attributed to heightened defect concentration. These properties find a utility in Optoelectronic device applications. Magnetic analysis indicated that incorporating a trivalent dopant (Er+3) into the Ti-O lattice enhanced ferromagnetic properties.

Comprehensive investigation of gas hold-up in a double coaxial mixer with shear-thinning fluids exhibiting yield stress: Experimental, numerical, and artificial neural network approaches

This study addresses the challenge of uneven gas dispersion in yield-stress, non-Newtonian fluids, commonly encountered in industries such as biopharmaceuticals, cosmetics, and food processing. While previous research demonstrated the advantages of dual coaxial mixers for pseudoplastic fluids, limited attention has been given to aerating yield-pseudoplastic fluids with higher aspect ratios. This study bridges that gap by investigating both local and global gas hold-up under various conditions, utilizing electrical resistance tomography and computational fluid dynamics. Key findings showed that increasing the anchor speed from stationary to 30 rpm significantly enhanced aeration efficiency (gas hold-up per specific power consumption), with improvements of 78 % in UP-CO mode and 25 % in UP-COUNTER mode at Nc = 350 rpm and Qg = 20 L/min. These results underscore enhanced gas dispersion under specific operating conditions, driving overall process intensification. To ensure accurate prediction of gas hold-up, both dimensional and dimensionless empirical correlations, along with an artificial neural networks (ANNs) model, were developed. The ANNs model exhibited superior accuracy, achieving R² values of 0.99 for both rotation modes, outperforming empirical models, which achieved R² values of 0.90 and 0.89 for UP-CO and UP-COUNTER modes, respectively.

Exergy efficiency improvement by compression heat recovery for an integrated natural gas liquefaction-CO2 capture-NGL recovery process

For liquefied natual gas production, cryogenic distillation offers lower thermal energy consumption and a more compact footprint for carbon capture unit than the widely used chemical absorption. However, the reduction in thermal energy consumption comes at the cost of increased power consumption. To reduce the power consumption of cryogenic distillation based natural gas lqiuefaction plants, an integrated process for liquefied natual gas production, cryogenic CO2 capture and natural gas liquids recovery is proposed, which is called the base process. This base process is further integrated with a heat recovery unit (Organic Rankine cycle or Kalina cycle) to investigate the optimal utilization of compression heat in the system. The proposed processes are modeled in Aspen HYSYS and optimized using a genetic algorithm installed in Matlab. The results show that specific power consumption of the base case is 0.385 kWh/Nm3 NG. Due to the lack of compression heat recovery, significant exergy loss occurs at the water coolers, accounting for approximately 37 % of the total system exergy destruction. Among the evaluated methods, the supercritical Organic Rankine cycle, using R1234ze as the working fluid, recovers approximately 60 % of the exergy from compression heat with an 8.7 % improvement in system exergy efficiency. The subcritical Organic Rankine cycle, using R600a as the working fluid, achieves a slightly lower exergy efficiency improvement of 7.1 %. The Kalina cycle, while less efficient, still improves the system’s exergy efficiency by 6.3 %. Economic analysis reveals that the total annualized cost of the base process is $8,441,416, with a levelized cost of $0.1411/kg. The subcritical Organic Rankine Cycle provides the most cost-effective solution, with the lowest total annualized cost of $8,305,154 and a levelized cost of $0.1402/kg. The Kalina cycle ranks second in cost-effectiveness, with a total annualized cost of $8,345,914 and a levelized cost of $0.1405/kg NG. Although the supercritical ORC requires the highest capital investment, it proves more cost-effective than the base process due to its reduced annual operating costs.

Design and optimization of large-scale natural gas liquefaction process based on triple refrigeration cycles

In large-scale natural gas liquefaction, minimizing specific energy consumption has consistently been a primary objective. This study aims to develop a large-scale natural gas liquefaction process that balances energy efficiency and cost-effectiveness, presenting a viable option for industrial production. By employing a refrigerant strategy of “propane + mixed refrigerant + mixed refrigerant”, a novel large-scale natural gas liquefaction process based on triple refrigeration cycles (TRC) is proposed. To address the challenge of boil-off gas (BOG) re-liquefaction, the TRC process is further refined to integrate BOG re-liquefaction (TRC-BR). Thermodynamic models are built for the proposed TRC and TRC-BR processes, as well as the propane pre-cooled mixed refrigerant (C3MR) and AP-X processes as baseline cases. Global optimization is conducted using the Particle Swarm Optimization (PSO) algorithm, with the specific power consumption (SPC) serves as the objective function. The results reveal that the SPC of the TRC and TRC-BR processes are 0.2726 and 0.2704 kWh/kg-LNG respectively. Compared with the C3MR and AP-X processes, the SPC of the TRC decrease by 1.54% and 4.84%, respectively. The total investments for the TRC and TRC-BR processes are estimated at a similar level compared to the baseline cases, demonstrating their significant potential for industrial application.

Microwave-assisted vanadium interpolated cobalt-MOF cathode assembled 3 V high performing asymmetric supercapacitor with ionic liquid gel polymer electrolyte

To ameliorate energy storage and conversion, metal synergy, and structural stability, bimetal-assembled metal–organic frameworks (MOFs) are delved into. Augmented surface area, pseudo capacitance, and the ability to alter the MOF edifice of layered oxide have drawn interest in MOF-based oxide layered structures. Simple microwave and hydrothermal techniques use dimethyl formamide and water as solvents and annealing methods to generate the bimetallic organic framework’s Co3V2O8 and Co3VO4 cathode material. Those customized shapes boost redox sites and reduce ion electron distance. Due to cobalt’s faradaic process and vanadium’s highly layered attributes, supercapacitor electrode response is significant. Co3V2O8 has 1391F/g specific capacitance at 2 mV/s scan rate and 1309F/g at 4 mA/cm2 implemented current value. After 10,000 cycles, the cathode material depicts 89 % capacity retention and 98 % coulombic efficiency. Biowaste-derived activated carbon is combined with a Co3V2O8 cathode for asymmetric supercapacitor storage. That device works on 3 V windows with ionic liquid gel polymer electrolyte. With a maximum specific energy of 329.3 Wh/kg and specific power of 15250 W/kg, the achieved galvanometric capacitance is 263.5F/g and 220 mAh/g at the 9 mA/cm2 current and showed 88.5 % potential stability after 10,000 cycles. These findings corroborate its use as a supercapacitor cathode.

Nanocomposite Material Sb2S3:SnS:MnS2 its Fabrication and Utilization as Efficient Electrode for Energy Storage in Supercapacitor

AbstractThe nanocomposite material Sb2S3: SnS:MnS2 was fabricated by single precursor technique by using dithio‐carbamate ligand as Sb2S3:SnS:MnS2 (DDTC) complex. An internal and external look at the anatomy and activity of the substance was obtained by using a variety of analytical techniques like XRD, FTIR, UV‐Vis and SEM. Additionally, various electro‐analytical tools like LSV, CV, GCD and EIS were applied to confirm material's rich electro‐active capability for photoactive electrode. XRD revealed its average crystallite size of 12.33 nm with 82.8 % crystallinity. Optical characteristics represented describe effective semiconducting nature of nanomaterials with optimum band gap of 2.65 eV. By using electrochemical processes, LSV and CV demonstrated fertile opto‐electrical nature of Sb2S3: SnS: MnS2 (DDTC) material with specific capacitance, Csp, of 1080 F/g at scan rate of 2 mV/s. With a high specific power density of 2656 W/kg, the GCD technique attempted to validate the nature of the material as an electrode with a good charge‐discharge mechanism. In EIS, low series resistance, Rs=0.73 Ω, was observed to be very beneficial argument in validating the nanocomposite synthesized in this research project as effective and low‐cost material which can be applied in different energy producing and storing devices like solar system and super‐capacitors etc.

Transition metal-assisted layer-by-layer binder free deposition for high-performance energy storage devices

The increasing energy demands of the world necessitate the development of advanced energy storage systems. Hybrid supercapacitors (HSCs) have emerged as promising candidates, combining the high specific power density (PS) of supercapacitors (SCs) with the high specific energy density (ES) of batteries (BATs). However, its performance is dependent on the properties of electrode materials, which need enhancements in conductivity, surface area, and electrochemical stability. In this study, we utilized magnetron sputtering technique for exploring the potential of interface engineering to improve the electrochemical performance of tungsten disulfide (WS2) as a battery grade electrode material by incorporating chromium (Cr) and titanium (Ti) as an interfacial layer. This strategic modification significantly increased the conductivity, charge transfer efficiency, and structural stability of the WS2 electrode. Electrochemical experimentation in both half-cell and full-cell configurations revealed that the WS2/Cr and WS2/Ti electrode exhibits superior CS [2400 and 3800] F/g, respectively compared to pristine WS2. Fabricated WS2/Cr//AC and WS2/Ti//AC attained ES [95 and 117] Wh/kg and PS [6800 and 8500] W/kg, respectively. The outcomes from the electrochemical testing further demonstrated the superior cyclic stability of WS2/Cr//AC and WS2/Ti//AC with [96.5 and 98.3] % which shows that Cr and Ti as an interfacial layer not only mitigates the limitations of WS2 but also enables the devices to achieve higher performance metrics, underscoring the critical role of interface engineering in advancing HSCs technologies.

Y-Shaped Acceptor-π-Donor-π-Acceptor Configured Anthraquinone-Tethered Phenothiazine Molecular Scaffold for High-Performance Organic Pseudocapacitors.

For the first time acceptor-π-donor-π-acceptor (A-π-D-π-A) based Y-type organic electrode material have been designed and successfully utilized in supercapacitor (SC) application. This Y-type molecular architecture coined as AQ-Im-PTZ-Im-AQ based on anthraquinone (AQ) (A)-imidazole (Im) (π)-phenothiazine (PTZ) (D)-imidazole (Im) (π)-anthraquinone (AQ) (A) in combination with graphite foil (GF). As-fabricated PTZ-Im-AQ/GF and AQ-Im-PTZ-Im-AQ/GF electrode have shown the good energy storage properties in three-electrode supercapacitor system. Moreover, two-electrode symmetric supercapacitor (SSC) device based on AQ-Im-PTZ-Im-AQ/GF electrode exhibited specific capacitance (Csp) of 68.97 F g-1 at 1 A g-1 current density. The specific electron density (ED) of SSC was observed to be 12.06 Wh kg-1 at a specific power density (PD) of 1798.50 W kg-1. The SSC device exhibited 81.62 % of Csp retention after 5000 galvanostatic charge-discharge (GCD) cycles. For real world applications, AQ-Im-PTZ-Im-AQ/GF electrode was tested in symmetric Csp coin cell with applied potential voltage window of -0.4 to 1.0 V was found to be 112.32 F g-1 at 0.5 A g-1. Moreover, it realized high specific capacitance and high energy density of 19.66 Wh kg-1 at 891.94 W kg-1 power density. As a results, AQ-Im-PTZ-Im-AQ/GF make as an attractive electrode material for application in next-generation SCs.

Synthesis and characterization of activated carbon derived from agricultural waste (cocoa pod husks) as potential electrode for symmetric supercapacitor

Biomass waste of cocoa pod husks is adopted as starting material to synthesize Activated carbon (ACC) using a tube furnace via KOH activation with temperature ranging from 500 °C to 800 °C. The activated carbon prepared at 600 °C (ACC 600 °C) shows improved qualities than the other prepared samples, according to the physico-chemical analyses. A sponge-like morphology, amorphous structure, and microporous and mesoporous carbon are observed in the synthesized material. Trasatti approach is adopted to verify the storage mechanism of the activated carbon material (ACC 600 °C) with the percentage contribution of capacitive and diffusion-controlled effect as 92.4732% and 7.5268% for positive electrode while the negative electrode possesses 75.565% and 24.435% at scan rate of 50 mVs−1. A symmetric device is fabricated from the ACC 600 °C, which gives a maximum specific energy (S.E.) of 19 Wh kg−1 with a corresponding specific power (S.P.) of 453 W kg−1 at a specific current of 0.5 A g−1 in 2.5 M KNO3 solution. The coulombic efficiency of the device is 99.6% after 10000 cycles with 72% capacitance retention. The obtained results suggest that the activated carbon derived from cocoa pod husks could be used as a promising material for supercapacitor's application.

Broadband Light Harvesting from Scalable Two-Dimensional Semiconductor Multi-Heterostructures.

Broadband absorption in the visible spectrum is essential in optoelectronic applications that involve power conversion such as photovoltaics and photocatalysis. Most ultrathin broadband absorbers use parasitic plasmonic structures that maximize absorption using surface plasmons and/or Fabry-Perot cavities, which limits the weight efficiency of the device. Here, we show the theoretical and experimental realization of an unpatterned/planar semiconductor thin-film absorber based on monolayer transition-metal dichalcogenides. We experimentally demonstrate an average total absorption in the visible range (450-700 nm) of >70% using <4 nm of semiconductor absorbing materials scalable over large areas with vapor phase growth techniques. Our analysis suggests that a power conversion efficiency of 15.54% and a specific power >300 W g-1 may be achieved in a photovoltaic cell based on this metamaterial absorber.