Li-air batteries attract abundant attention in recent years with superior performance, and have largely replaced traditional methods of energy storage. The main objective of Li–air battery is to ...provide long-range electric-vehicles, while functioning as an environmentally friendly and compact energy storage solution. They offer the highest theoretical energy density (3500 Wh/kg), almost 20% higher than the ordinary Li-ion batteries. Nonetheless, Li-air batteries still face numerous issues, the most serious of which are high overpotential and parasitic reactions. Several redox mediators (RM) have been studied in order to reduce the high overpotential and the influence of side reactions. RM function in the electrolyte as soluble catalysts, limiting the formation of singlet oxygen while promoting the formation of discharge product Li2O2. This research primarily focuses on the optimization of Li-air cells with different redox mediators in conjunction with appropriate electrolyte, as a result reducing overpotential, parasitic byproducts and increasing efficiency. Under standard electrolytic conditions, ruthenocene exhibits high stability by completing 83 cycles, thus outperforming the other mediators being investigated. Further, di-tert-butyl-1,4-benzoquinone is more commonly used for discharge reaction and has been shown to increase the capacity of Li–O2 batteries by 80 times. This study reconfirms lithium bis(trifluoromethylsulfonyl) imide in tetraethyleneglycol dimethylether as the most stable electrolyte.
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•LABs offer high energy density but pose overpotential and parasitic reactions.•Redox mediators or soluble catalysts are studied to reduce overpotential issues.•Ruthenocene is highly stable and outperforms all other mediators.•DBBQ is commonly used for discharge and increases the capacity of LABs 80 times.
Hydrogels wound dressings have enormous advantages due to their ability to absorb high wound exudate, capacity to load drugs, and provide quick pain relief. The use of hydrogels as wound dressings in ...their original form is a considerable challenge, as these are difficult to apply on wounds without support. Therefore, the incorporation of polymeric hydrogels with a certain substrate is an emerging field of interest. The present study fabricated cellulose hydrogel using the sol-gel technique and reinforced it with nonwoven cotton for sustainable wound dressing application. The nonwoven cotton was immersed inside the prepared solution of cellulose and heated at 50 °C for 2 h to form cellulose hydrogel-nonwoven cotton composites and characterized for a range of properties. In addition, the prepared hydrogel composite was also loaded with titania particles to attain antibacterial properties. The Fourier transform infrared spectroscopy and scanning electron microscopy confirmed the formation of cellulose hydrogel layers inside the nonwoven cotton structure. The fabricated composite hydrogels showed good moisture management and air permeability, which are essential for comfortable wound healing. The wound exudate testing revealed that the fluid absorptive capacity of cellulose hydrogel nonwoven cotton composite was improved significantly in comparison to pure nonwoven cotton. The results reveal the successful hydrogel formation, having excellent absorbing, antimicrobial, and sustainable properties.
This study is designed to examine the feasibility of the solar water heating (SWH) system for sustainable tourism in Gilgit-Baltistan (GB) of Pakistan and a tourist resort is taken as a base case. ...Hot water demand, solar irradiance and economic feasibility are the key parameters considered to investigate the potential of SWH systems using simulation tool T*SOL. Three different types of solar collectors were investigated, based on solar fraction, maximum collector temperature and overall system efficiency. Among these collectors, the evacuated tube collectors (ETC) show high solar fraction, efficiency and CO2 emissions saved as compared to flat plate collectors (FPC) and unglazed collectors (UnGC), for both locations. The ETC shows 75 % solar fraction, 40 % efficiency, and 676 kg CO2 emission saved and payback period of is recorded 6.6 years for Gilgit. While for Skardu, 84 % solar fraction, 36 % efficiency, 756 kg CO2 emissions avoided and payback period of 4.6 years is analysed. Sensitivity analysis based on design parameters such as collector area, tilt angle and tank volume is performed to highlight the important design considerations. Based on the techno-economic analysis, it is concluded that ETC is the most feasible SWH system for the northern regions of Pakistan.
In this study, a new method to prepare polyvinyl alcohol (PVA) hydrogel-based woven fabric composite is presented. In this method, the woven fabric was first stitched with PVA yarn and then subjected ...to the borax solution for simultaneously dissolving and crosslinking PVA. The prepared PVA hydrogel-based woven fabric composite was chemically, mechanically, and thermally characterized. FTIR analysis was performed to confirm the crosslinking of PVA on the reinforced fabric surface. X-ray diffraction analysis was carried out to investigate the crystallinity of the composite. An optical microscope was used to investigate the surface morphology of the composites. Moreover, a DSC analysis was done to investigate the thermal characteristics of the composite. The mechanical and fluid absorbency characteristics of the composite were analyzed to investigate the effect of the concentration of PVA yarn on the tensile strength and water absorbency of composites. The results showed that the tensile strength and rigidity of the composite increased by increasing the PVA yarn content in the composite.
Due to the rising trend in 2-Dimensional material, graphene has gained a lot of interest in the recent past. Graphene is the 2D carbon allotrope with high strength and improved mechanical, chemical, ...and electrical properties. Despite being excellent properties among other types of carbon allotropes but still, graphene use is limited because of its costly synthesis technique. In this research, a cheap and effective method is adapted for the preparation of graphene from graphite powder. The graphite powder is thermally treated to prepare the exfoliated graphite then exfoliated graphite is milled to produce the 2D graphene sheets. The synthesized graphene is characterized by X-Ray Diffractometry (XRD) and Scanning Electron Microscope (SEM). The XRD results show that graphene is successfully synthesized, and SEM results show that graphene is 2D which can be used in various applications. This research provides a direction for the synthesis of graphene from graphite powder on an industrial scale.
•The δ-MnO2/N-rGO nanocomposite (MNGC) has been synthesized by a simple template-free hydrothermal approach.•LSV results of MNGC showed improved ORR performance as compared to MnO2 and N-rGO in terms ...of the onset potential, half wave potential and limiting current.•The MNGC electrode displayed superior cyclic performances of lithium air battery with stable specific capacity, decreased overpotential, reversibility and rate capability.•The Li-O2 battery was also tested with MNGN electrode for limited discharge capacity of 500 m Ah/g; long-term cycling was achieved without any electrolyte degradation.•As, high specific capacity of 5250 mAh /g was obtained even with high current density of 0.2 mA /cm2.
Among all the electrocatalysts for Lithium-Air battery (Li-air), Platinum Pt is the best performing cathode material. However, the high cost of noble Pt metal and scarcity nature impedes the use of Pt-based catalysts from being extensivity used in commercial applications. Therefore, there is an urgent need to develop an efficient and cost-effective alternate electrocatalyst to replace Pt-based materials in lithium-oxygen (Li-O2) battaries. In the present work, δ-MnO2/N-rGO composite (MNGC) has been synthesized by a simple non-template hydrothermal approach. MNGC with a porous wall structure composed of ultrathin nanosheets exhibits excellent electrochemical properties for oxidation–reduction reaction (ORR). MNGC can provide numerous pathways for abundant oxygen and electrolyte access to facilitate the mass transfer of lithium-ion. Such a well-designed structure offers the right electrocatalyst for the air cathode in lithium-oxygen (Li-O2) battaries. The prepared samples principal characteristics are analyzed, which verified the successful synthesis of sheet-like δ-MnO2 grown over the surface of nitrogen-doped reduced graphene oxide (N-rGO). Linear sweep voltammetry (LSV) results of MNGC showed enhanced ORR performance compared to MnO2 and N-rGO in terms of the half-wave potential, limiting current, and onset potential. MNGC electrode displayed superior cyclic performances of Li-air with a stable specific capacity, decreased overpotential, reversibility, and rate capability. Li-O2 battery was also tested with MNGN electrode for limited discharge capacity of 500 mAh/g, long-term cycling was achieved without electrolyte degradation. A high specific capacity of 5250 mAh/g was obtained at a high current density of 0.2 mA/cm2. The interlinked effect of δ–MnO2 and N–rGO for supporting the electrochemical interaction between O2 and Li is explained for improved columbic and energy efficiency of Li–O2 battery
In this study, metallic copper (Cu) nanowires are synthesized by reducing thermally synthesized CuO nanowires under an indigenously developed hydrogen plasma system. The X-ray diffraction (XRD) ...results of the plasma-synthesized nanowires indicate the presence of metallic copper (111) and (200) and the field emission scanning electron microscopy (FESEM) further affirms the findings by presenting a stark difference in contrast of the nanowires before and after plasma treatment with diameters of 50 and 100 nm, respectively. The nanowires are studied for hydrogen evolution reaction in a neutral medium and they show excellent performance than the previously reported studies on bulk copper, with an overpotential of 210 mV at a current density of 10 mA/cm2 and an exchange current density of 60 exp-5 A/cm2 which is an order of magnitude larger than the reported values on bulk copper. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy indicates that the surface of the nanowires is highly rich in metallic copper resulting in better electrochemical performance of the metallic Cu nanowires in a neutral environment.
•DBD plasma technique is used for the synthesis of Copper nanowires.•Metallic Copper nanowires are successfully tested for HER.•Exchange current density of up to 60exp-5 A/cm2 is observed.•Overpotential requirements attain 210 mV to reach 10 mA/cm2.
Wound healing is a complex process which requires an appropriate environment for quick healing. Recently, biodegradable hydrogel-based wound dressings have been seen to have high potential owing to ...their biodegradability and hydrated molecular structure. In this work, a novel biodegradable composite of sodium alginate hydrogel with wool needle-punched nonwoven fabric was produced for wound dressing by sol–gel technique. The wool nonwoven was dipped in the sodium alginate-water solution and then soaked in calcium chloride solution which resulted in hydrogel formation. FTIR analysis and SEM images confirm the presence of alginate hydrogel inside the needle-punched wool nonwoven fabric. The wound exudate absorbing capacity of hydrogel based wool nonwoven was increased 30 times as compared to pure wool nonwoven. Moreover, the tensile strength and moisture management properties of hydrogel based nonwoven were also enhanced. The unique combination of alginate hydrogel with biocompatible wool nonwoven fabric provides moist environment and can help in cell proliferation during wound healing process.
In this work, partial oxidation of methane (POM) was investigated using Mg-Ni-Al (MNA) hydrotalcite promoted CeO2 catalyst in a fixed bed reactor. MNA hydrotalcite was synthesized using the ...co-precipitation process, while CeO2 was incorporated via the wetness impregnation technique. The CeO2@MNA samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) technique. The catalytic activity of CeO2 promoted MNA (CeO2@MNA) for POM reaction was evaluated for various CeO2 loading kept the feed ratio CH4/O2 = 2 at 850 °C. The catalyst containing 10 wt% cerium loading (10%CeO2@MNA) showed 94% CH4 conversion with H2/CO ratio above 2.0, that is more suitable for FT synthesis. The performance of catalyst is attributed to highly crystalline stable CeO2@MNA with better Ce-MNA interactions withstand for 35 h time on stream. Furthermore, the spent catalyst was examined by TGA, SEM-EDS, and XRD to evaluate the carbon formation and structural changes during the span of reaction time.
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•CeO2@MgNiAl (MNA) hydrotalcite is synthesised for POM reaction.•CeO2 addition over MNA greatly improved the H2/CO ratio.•The catalyst is stable for more than 35 h on POM reaction.•The spent catalyst shows no sign of graphitic carbon after 35 h.
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