R. Kannan

Improvement of proton conductivity in nanocomposite polyvinyl alcohol (PVA)/chitosan (CS) blend membranes

The composite membranes are prepared with poly(vinyl alcohol) (PVA), chitosan (CS) and montmorillonite (MMT) using a solution casting technique where the chemical composition of CS and MMT in the prepared composite membranes are varied in steps of 5 wt%. The structural properties, thermal stability, hydrolytic stability and transport properties of the prepared membranes were investigated using various characterization methods, like Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), water uptake, methanol uptake, planner swelling, thickness swelling, ion exchange capacity (IEC) and proton conductivity measurements. It is noticed that the addition of both CS and MMT into the PVA polymer enhances the mechanical, thermal and transport properties of the prepared composite membranes. All the membranes are homogenous, as revealed by the XRD studies. In the present work, ionic transport studies of PVA/CS/MMT membranes were analysed and the membrane PCH05 exhibited the best electrical properties of all the prepared membranes. It is expected that PCH05 membrane will serve as a good candidate for use in direct methanol fuel cells (DMFC) in the near future.

Facile synthesis and characterization of a reduced graphene oxide/halloysite nanotubes/hexagonal boron nitride (RGO/HNT/h-BN) hybrid nanocomposite and its potential application in hydrogen storage

The hydrogen storage performance of hybrid nanocomposites composed of reduced graphene oxide, acid treated halloysite nanotubes and hexagonal boron nitride nanoparticles (RGO/A-HNT/h-BN) was studied. A modified Hummers method and sonication assisted liquid-phase exfoliation technique were adopted for the synthesis of GO and preparation of hybrid nanocomposites (RGO/A-HNT/h-BN), respectively. The prepared hybrid nanocomposites were analyzed using X-ray diffraction (XRD), micro-Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Thermo Gravimetric Analysis (TGA). Using a Sieverts-like hydrogenation setup, the hydrogen storage properties of RGO/A-HNT/h-BN hybrid nanocomposite were examined. The RGO/A-HNT/h-BN hybrid nanocomposite exhibits 3.3 wt% of storage capacity at 50 °C and 100% desorption of stored hydrogen was observed in the temperature range of 119–143 °C. The average binding energy of stored hydrogen was found to be 0.32 eV and it lies in the recommended range of US-DOE targets. The reusability test confirms 93.3% storage capacity for the fifth cycle of hydrogenation. Hence it is expected that the prepared RGO/A-HNT/h-BN hybrid nanocomposite may serve as a promising hydrogen storage medium for fuel cell applications.

Experimental investigation on hydrogen storage in polymer based nanocomposite

In the present study, the hydrogen storage performance of SPEEK-h-BN nanocomposite membrane is investigated. The SPEEK-h-BN nanocomposite is prepared by using phase inversion technique. Hydrogen adsorption studies have been carried out for the membranes using a Seiverts-like hydrogenation setup. The synthesized membranes are characterized by 1H NMR, Raman spectroscopy, SEM, EDS, CHN-elemental analysis and TGA to analyze the membrane at various steps of experiments. It is observed that the SPEEK-h-BN nanocomposite membrane shows the enhanced performance compared to the pure SPEEK with a maximum storage capacity of 2.98 wt. % at 150 °C and the adsorbed hydrogen possess the average binding energy of 0.38 eV, while the pure SPEEK shows the storage capacity of 0.66 wt. % at 150 °C and the average binding energy of hydrogen of 0.36 eV. The TGA study shows the dehydrogenation of hydrogenated SPEEK-h-BN nanocomposite favors in the temperature range of 214 -218 °C.

Role of structural modifications of montmorillonite, electrical properties effect, physical behavior of nanocomposite proton conducting membranes for direct methanol fuel cell applications

Abstract Proton exchange membranes have been synthesized from polyimide (PI) doped with different contents of montmorillonite (MMT) which was obtained by solution casting technique. The enhancement of conductivity was achieved through modification with the MMT. Prepared membranes were systematically characterized in terms of ion exchange capacity, water uptake, methanol uptake, swelling behavior and proton conductivity. Fourier transform infrared spectroscopy and X-ray diffraction measurements were used to confirm the structures of the PI/MMT composite electrolyte membranes. SEM surface morphological images of the composite membranes showed that the MMT nanoclay particles were dispersed uniformly within the membrane what was also reflected in XRD results which indicated a good compatibility of MMT particles with the polymer complex. The TGA spectra showed that the thermal stability of the membrane was reduced by adding MMT into the polymer network. The prepared membrane with 10 wt.% of modified MMT exhibited the highest proton conductivity value of 7.06 × 10-2 S·cm-1 at 70 °C. These results imply the potential application of the PI/MMT composite membranes as improved PEMs for DMFC applications.

Lithium ion conduction in plasticizer based composite gel polymer electrolytes with the addition of SiO2

Abstract Composite gel polymer electrolytes (CGPE) were prepared using 1,3 Dioxolane (DIOX)/Tetraethyleneglycol dimethylether (TEGDME) as a combination of plasticizers, comprising with PEO, lithium salt (LiClO4) with the addition of filler SiO2. The composite gel polymer electrolytes were prepared by simple solution casting technique in an argon atmosphere. The electrolyte films were subjected to thermal, structural, morphological and electrochemical ac impedance analysis. A Lithium symmetric cell (Li/CGPE/Li) was fabricated and interfacial resistance as a function of time was studied. The film was thermally stable up to 298 °C. The ionic conductivity of high conducting sample is obtained in the order of 10−4 at ambient temperature. The transport properties of the gel polymer electrolyte were measured and the values are 0.6 which is sufficient for battery applications. The stability of the electrolyte film was analysed using the linear sweep voltammetry technique and the film was stable up to 3.4 V.

Synthesis of polyetherimide / halloysite nanotubes (PEI/HNTs) based nanocomposite membrane towards hydrogen storage

Even though hydrogen is considered as green and clean energy sources of future, the blooming of hydrogen economy mainly relies on the development of safe and efficient hydrogen storage medium. The present work is aimed at the synthesis and characterization of polyetherimide/acid treated halloysite nanotubes (PEI/A-HNTs) nanocomposite membranes for solid state hydrogen storage medium, where phase inversion technique was adopted for the synthesis of nanocomposite membrane. The synthesized PEI/A-HNTs nanocomposite membranes were characterized by XRD, FTIR, SEM, EDX, CHNS elemental analysis and TGA. Hydrogenation studies were performed using a Sievert’s-like hydrogenation setup. The important conclusions arrived from the present work are the PEI/A-HNTs nanocomposite membranes have better performance with a maximum hydrogen storage capacity of 3.6 wt% at 100 °C than pristine PEI. The adsorbed hydrogen possesses the average binding energy of 0.31 eV which lies in the recommended range of US- DOE 2020 targets. Hence it is expected that the PEI/A-HNTs nanocomposite membranes may have bright extent in the scenario of hydrogen fuel cell applications.Even though hydrogen is considered as green and clean energy sources of future, the blooming of hydrogen economy mainly relies on the development of safe and efficient hydrogen storage medium. The present work is aimed at the synthesis and characterization of polyetherimide/acid treated halloysite nanotubes (PEI/A-HNTs) nanocomposite membranes for solid state hydrogen storage medium, where phase inversion technique was adopted for the synthesis of nanocomposite membrane. The synthesized PEI/A-HNTs nanocomposite membranes were characterized by XRD, FTIR, SEM, EDX, CHNS elemental analysis and TGA. Hydrogenation studies were performed using a Sievert’s-like hydrogenation setup. The important conclusions arrived from the present work are the PEI/A-HNTs nanocomposite membranes have better performance with a maximum hydrogen storage capacity of 3.6 wt% at 100 °C than pristine PEI. The adsorbed hydrogen possesses the average binding energy of 0.31 eV which lies in the recommended range of US- DOE 2020 targets. H...

Studies on optical and electrical properties of SILAR-deposited CuO thin films

CuO thin films prepared by SILAR technique using aqueous solutions of various pH values and their characterization are presented in this report. The pH dependence on structural, morphological, optical and electrical properties of the prepared films is studied. Thickness of films is found to vary in between 0.52 and 0.82 µm. Microstructural parameters such as crystallite size, strain and dislocation density of the film have been evaluated. The crystallographic behaviour of the film has shown that all the coated thin films are in monoclinic structure with (002) preferred orientation. The size of the crystallites is found to increase with the pH values. Surface morphological behaviour of the films prepared using different pH values are analysed. Optical properties of the films were analysed from absorption and transmittance studies of CuO thin films. Band gap energy values of CuO thin films have been found to decrease from 2.12 to 1.91 eV with increasing pH values of the solution. The thin film formed at a solution pH 11 has shown least resistivity and high carrier concentration. The I-V characteristics of n-Si/p-CuO heterojunction under 200-watts halogen lamp illumination show open-circuit voltage of ~ 0.37 V and short-circuit current of ~1.02 × 10−6 A.

High conductive proton exchange membrane (SPEEK/MMT) and its characterization

Abstract Proton exchange membranes (PEMs) are prepared by solution casting method by varying the contents of Sulfonated Poly ether ether ketone (SPEEK) and Montmorillonite (MMT) nanoclay. The degree of sulfonation of synthesized SPEEK polymer is around 64% which is obtained from the 1H-NMR analysis. The liquid uptake, swelling ratio and ion exchange capacity of the membranes were studied. The chemical and structural properties of the membranes were analyzed by Fourier –Transform Spectroscopy and X-ray diffraction spectroscopy. The composite membrane with 1.5 wt-% of MMT nanoclay exhibits high proton conductivity value around 1.1086 × 10−1 S cm−1 at 70 °C under 100% relative humidity. The dielectric properties of the membranes were also analyzed with the support of impedance data. The obtained results demonstrate that the developed composite membrane serve as a potential candidate for electro chemical applications.

Effect of Modified Nanoclay Composite on Blended PVDF/PEG Electrolyte Membranes for Fuel Cell Applications

This research work describes the fabrication of polymer blend nanocomposite membranes using the solution casting method. These membranes were fabricated with Poly (Vinylidene Fluoride) (PVdF) as ho...

Hydrogen storage performance of functionalized hexagonal boron nitride for fuel cell applications

Developing light weight, safe, efficient and compact hydrogen storage medium are still the major concerns for the blooming of hydrogen based energy economy. In the present article, activated hexagonal boron nitride (ABN) and ABN functionalized with lithium borohydride (ABN-LiBH4) nanocomposite based hydrogen storage medium are synthesized. where a facile solvent-assistant technique was adopted for the preparation of ABN-LiBH4 nanocomposite. The prepared hydrogen storage medium was subjected to various characterization techniques such as XRD, FTIR, SEM, EDX, CHNS - elemental analysis and TGA. Sievert’s-like hydrogenation setup has been utilized for hydrogenation studies. It is noticed that the ABN-LiBH4 nanocomposite exhibits an attractive high gravimetric density of 1.67 wt% at 100 °C than pristine ABN. Moreover the stored hydrogen is released in the temperature range of 115 - 150 °C and possesses an average binding energy of 0.31 eV. These results indicate that the prepared ABN-LiBH4 nanocomposite paves a way to potential solid state hydrogen storage medium towards fuel cell technology as per the targets set by US Department of Energy (DOE).Developing light weight, safe, efficient and compact hydrogen storage medium are still the major concerns for the blooming of hydrogen based energy economy. In the present article, activated hexagonal boron nitride (ABN) and ABN functionalized with lithium borohydride (ABN-LiBH4) nanocomposite based hydrogen storage medium are synthesized. where a facile solvent-assistant technique was adopted for the preparation of ABN-LiBH4 nanocomposite. The prepared hydrogen storage medium was subjected to various characterization techniques such as XRD, FTIR, SEM, EDX, CHNS - elemental analysis and TGA. Sievert’s-like hydrogenation setup has been utilized for hydrogenation studies. It is noticed that the ABN-LiBH4 nanocomposite exhibits an attractive high gravimetric density of 1.67 wt% at 100 °C than pristine ABN. Moreover the stored hydrogen is released in the temperature range of 115 - 150 °C and possesses an average binding energy of 0.31 eV. These results indicate that the prepared ABN-LiBH4 nanocomposite paves ...