"Green" -electrospun Metal Oxide Nanowires for High Performance Supercapacitors

Storage of energy under the electrochemical double layer and fast reversible redox reaction mode, which devices are known as supercapacitors, with simultaneously high energy and power densities is an active area of research recently to develop deployable clean energy devices. The transition metal oxide semiconductors such as CuO, RuO2, MnO2, etc. offers pseudo capacitance arise from an electrochemical reaction in addition to the conventional double layer capacitance; therefore, they are a preferred choice to build highly efficient supercapacitors. In this research, we have developed nanowires of a number of transition metal oxides including CuO, NiO and Co3O by a commercially viable nanofabrication technique, known as electrospinning, and studied their structural, morphological, and electrochemical properties. The nanowires of ~ 50 � 60 nm were obtained by annealing the electrospun polyvinyl alcohol fibrous mats containing a uniform dispersion of metal acetate. The supercapacitor devices were fabricated by dispersing the 70 wt.% active material in 15wt.% conducting carbon and 10 wt.% polyvinyl difluoride and pasted on a nickel foam substrate. KOH was used as the electrolyte. The specific capacitance and cycling stability of the devices were obtained from cyclic voltammetry and galvanostatic charge/discharge cycling, respectively. The devices exhibited a specific capacitance of ~620 F/g ,670 F/g and 1047 F/g for CuO, NiO and Co3O4, 4 respectively at a current density of 1 A/g in 6M KOH with a columbic efficiency of ~96%. The electrospun metal oxide nanowires could therefore be an acceptable choice for building highly efficient supercapacitor devices

Large Scale Synthesis of Binary Composite Nanowires in the Mn2O3-SnO2 System with Improved Charge Storage Capabilities

Large scale production of electrochemical materials in non-conventional morphologies such as nanowires has been a challenging issue. Besides, functional materials for a given application do not often offer all properties required for ideal performance; therefore, a composite is the most sought remedy. In this paper, we report large scale production of a composite nanowire, viz. Mn2O3-SnO2, and their constituent binary nanowires by a large scale electrospinning pilot plant consisting of 100 needles. Electrochemical characterization of thus produced composite nanowires showed nearly threefold increase in the discharge capacity compared to their single component counterparts: Mn2O3-SnO2 ∼53 mA h g−1 (specific capacitance, CS ∼384 F g−1); Mn2O3 ∼18 mA h g−1 (CS ∼164 F g−1); and SnO2 ∼14 mA h g−1 (CS ∼128 F g−1) at 1 A g−1 in 6 M KOH. The EIS studies showed that the characteristic resistances and time of the composite electrode are appreciably lower than their constituents. Owing to the scalability of the synthesis processes and promising capacitive properties achieved would lead the composite material as a competitive low-cost and high-performance supercapacitor electrode

Facile fabrication of thin metal oxide films on porous carbon for high density charge storage

In an effort to minimize the usage of non-renewable materials and to enhance the functionality of the renewable materials, we have developed thin metal oxide coated porous carbon derived from a highly abundant non-edible bio resource, i.e., palm kernel shell, using a one-step activation-coating procedure and demonstrated their superiority as a supercapacitive energy storage electrode. In a typical experiment, an optimized composition contained ~10 wt.% of Mn2O3 on activated carbon (AC); a supercapacitor electrode fabricated using this electrode showed higher rate capability and more than twice specific capacitance than pure carbon electrode and could be cycled over 5000 cycles without any appreciable capacity loss in 1 M Na2SO4 electrolyte. A symmetric supercapacitor prototype developed using the optimum electrode showed nearly four times higher energy density than the pure carbon owing to the enhancements in voltage window and capacitance. A lithium ion capacitor fabricated in half-cell configuration using 1 M LiPF6 electrolyte showed larger voltage window, superior capacitance and rate capability in the ~10 wt.% Mn2O3@AC than the pure analogue. These results demonstrate that the current protocol allows fabrication of superior charge storing electrodes using renewable materials functionalized by minimum quantity of earthborn materials

Fabric Parameter Effect on the Mechanical Properties of Woven Hemp Fabric Reinforced Composites as an Alternative to Wood Products

Hemp is a common natural fibre which has reliable properties and is available in the forms of staple fibres, yarns and fabrics. However, less works were done by using woven hemp fabric in composite materials, especially for an alternative to wood products. In this work, woven hemp fabrics in different fabric layering orientations have been used to reinforce vinyl ester resin by employing hand lay-up method. The properties of hemp fabric were used to investigate how these properties can affect the physical and mechanical behaviour of the fabricated composites. The results show that fabric properties and layering orientations contribute to the tensile, flexural and impact properties of the composites. Based on the comparison to wood and engineered wood products’ properties, the mechanical properties of composites are found to be comparable. The comparison also shows that the woven hemp fabric reinforced vinyl ester can be an alternative for wood and engineered wood products in building industries especially in low-load bearing applications

Flammability characteristics of chemical treated woven hemp fabric reinforced vinyl ester composites

In the present work, the treatments using sodium hydroxide, flame retardant chemical and combination of both sodium hydroxide and flame retardant changed the physical properties thus reduced the mechanical properties of woven hemp fabric and fabricated composites. However, the treatments increased the fire retardant properties of fabricated composites as indicated by the burning tests, thermogravimetry analyses and limiting oxygen index tests. An assessment based on woods and engineered wood products have shown that the fabricated composites are suitable to be used for building infrastructure materials as an alternative to wood products

Involvement of ethylene carbonate on the enhancement H+ carriers in structural and ionic conduction performance on alginate bio-based polymer electrolytes

This study investigates the structural and ionic conduction performance with the involvement of ethylene carbonate (EC) in a bio-based polymer electrolytes (BBPEs) system, based on alginate doped glycolic acid (GA). The solution casting technique was used to successfully prepare the BBPEs which were characterized with various approaches to evaluate their ionic conduction performance. It was revealed that at ambient temperature, an optimum ionic conductivity of 9.06 × 10−4 S cm−1 was achieved after the addition of 6 wt% EC, with an observed improvement of the amorphous phase and thermal stability. The enhancement of ionic conduction properties is believed to be due to the protonation (H+) enhancement, as proven by FTIR and TNM studies. The findings show that the developed alginate-GA-EC is a promising candidate for use as electrolytes in electrochemical devices that are based on H+ carriers

Involvement of ethylene carbonate on the enhancement H+ carriers in structural and ionic conduction performance on alginate bio-based polymer electrolytes

This study investigates the structural and ionic conduction performance with the involvement of ethylene carbonate (EC) in a bio-based polymer electrolytes (BBPEs) system, based on alginate doped glycolic acid (GA). The solution casting technique was used to successfully prepare the BBPEs which were characterized with various approaches to evaluate their ionic conduction performance. It was revealed that at ambient temperature, an optimum ionic conductivity of 9.06 × 10−4 S cm−1 was achieved after the addition of 6 wt% EC, with an observed improvement of the amorphous phase and thermal stability. The enhancement of ionic conduction properties is believed to be due to the protonation (H+) enhancement, as proven by FTIR and TNM studies. The findings show that the developed alginate-GA-EC is a promising candidate for use as electrolytes in electrochemical devices that are based on H+ carriers

Synthesis and Characterization of Polycaprolactone/Cellulose Acetate by Electrospinning for Wound Dressing Applications

Cellulose as a renewable material has received enormous interest in recent time with an effort to minimize the environmental load from mining earthborn functional materials as well as reducing carbon footprint. This work demonstrates that high quality cellulose could be produced from empty fruit bunch of oil palm plantation and could be developed into nanofibers. A small amount of poly (ε-caprolactone) (PCL) was added to the EFB driven cellulose acetate (CA) to develop them as nanofibers by electrospinning technique; this composition was further enhanced by adding curcumin, which is a natural anti-inflammatory, and compared their morphology, structure, mechanical and surface properties

Nanoarchitectonics of low process parameter synthesized porous carbon on enhanced performance with synergistic interaction of redox-active electrolyte for supercapacitor application

To develop materials of lower embodied energy and materials footprint for energy storage industry, the present work reports synthesis of porous carbon from a waste wetland weed (wild sugarcane) using low process parametric conditions (temperature and impregnation ratio) and their electrochemical capacitive (synonymously known as supercapacitors) charge storage performance in aqueous and redox active electrolytes. The phase, surface chemistry, physical surface, and morphology of the porous carbon thus developed are studied in detail using X-ray diffraction, gas adsorption measurements, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning and transmission electron microscopy techniques. Porous carbon synthesized at 500 °C, with the activator ZnCl2, resulted in a combination of micro and meso pores and a specific surface area ∼1294 m2 g−1. The optimized electrodes show outstanding energy storage performance, viz. specific capacitance of ∼414 F g−1 (three-electrode system) and ∼197 F g−1 (two-electrode system) at 1 A g−1 current density in aqueous 1 M H2SO4 electrolyte. The porous activated carbon showed high performance in terms of electrochemical stability of 96 % in half cell configuration for 10,000 cycles, while the symmetric device showed 80 % cyclic stability for 5000 cycles in full cell configuration. Addition of redox active 0.01 M hydroquinone in the 1 M H2SO4 significantly improved the storage capacity to 540 C g−1 at current density of 3 A g−1 in two-electrode configuration and maintained 72 % of capacity for 5000 cycles. The redox-active symmetric supercapacitors show an energy density ∼26.9 W h kg−1 and power density ∼5527 W kg−1 and other related electrochemical properties

Textile material forms for reinforcement materials: a review

This paper intended to give an insight of the textile material utilization as reinforcement in the composite materials. The discussion on textile definition and categorization will give some ideas for the reader to recognize textile materials and its role in this system. Simple categorization is referred to which textile materials are clustered into fibre, yarn and fabric regardless whether it is made synthetically or naturally. For every basic textile material form, few selected recent works have been discussed to show the utilization of textile material in research and industry. Composite made of textile fibres form is limited to low and medium load bearing application due to the difficulties of controlling the alignment, dispersion and distribution of fibres. Whereas yarn reinforcement gives more control on the composite materials due to the fibres is aligned in a yarn but the issue is more on the limited fabrication method. Utilization of textile fabric in composite as reinforcement is well recognized for high performance fabric so it is with natural fabric. Nonetheless, there is a limit of work considering fabric properties or parameters when characterize its composite to understand the fabric contribution in composite material