Prem P. Sharma

SGO/SPES-Based Highly Conducting Polymer Electrolyte Membranes for Fuel Cell Application

Proton-exchange membranes (PEMs) consisting of sulfonated poly(ether sulfone) (SPES) with enhanced electrochemical properties have been successfully prepared by incorporating different amount of sulfonated graphene oxide (SGO). Composite membranes are tested for proton conductivity (30-90 °C) and methanol crossover resistance to expose their potential for direct methanol fuel cell (DMFC) application. Incorporation of SGO considerably increases the ion-exchange capacity (IEC), water retention and proton conductivity and reduces the methanol permeability. Membranes have been characterized by FTIR, XRD, DSC, SEM, TEM, and AFM techniques. Intermolecular interactions between the components in composite membranes are established by FTIR. The distribution of SGO throughout the membrane matrix has been examined using SEM and TEM and found to be uniform. The maximum proton conductivity has been found in 5% SGO composite with higher methanol crossover resistance.

Preparation of graphene oxide nano-composite ion-exchange membranes for desalination application

Nano-composite ion-exchange membranes (IEMs) consisting of graphene oxide (GO) (0.5, 1, 2, 5 and 10%) (w/w) and sulfonated polyethersulfone (SPES) of thickness 180 μm are prepared with enhanced electrochemical properties. In particular, the transport properties of SPES are favourably manipulated by the incorporation of GO. Intermolecular interactions between the components in composite membranes are established by FTIR. Membranes are characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) which showed the uniform distribution of GO sheets in SPES matrix. The maximum ionic conductivity has been found in 10% GO composite with higher methanol crossover resistance and selectivity. Water desalination performance of the nano-composite membranes have been evaluated by ionic flux, power consumption and current efficiency during salt removal. 10% GO nano-composite membrane shows 3.51 mol m−2 h−1 ionic flux, 4.3 kW h kg−1 power consumption and 97.4% current efficiency for salt removal. The values of ionic flux and current efficiency are 19% and 12% higher respectively while 20% lower power consumption is observed as compared to SPES membrane. The strong interfacial interactions due to the insertion of GO nanofillers into the SPES matrix improve the thermal and mechanical properties of the nanocomposite membranes. Nano-composite membrane shows the better performance and higher stability which may be used for the practical application such as DMFC and electrodialysis.

Dramatic Improvement in Ionic Conductivity and Water Desalination Efficiency of SGO Composite Membranes

Energy efficient membranes of SGO (Sulfonated Graphene Oxide) into SPES (Sulfonated Polyethersulfone) matrix have been prepared containing different weight content of SGO. Proton conductivity and water retention capacity of membranes increases by increasing SGO while degree of swelling decreases. TEM micrograph shows the uniform distribution of SGO throughout the membrane. SGO-5 membrane shows the maximum proton conductivity (5.8 x 10−2 S/cm), which is almost double to the SPES with higher stability. SGO-5 membrane shows 4.73 mole.m−2h−1 ionic flux, 0.98 kWhkg−1 power consumption and 93.1% current-efficiency for salt removal, which are 62% and 15.2% higher, respectively, while 16% lower power consumption is observed as compared to SPES.

An environmentally friendly process for the synthesis of an fGO modified anion exchange membrane for electro-membrane applications

We report the synthesis of an anion exchange membrane (AEM) based on chemically covalently modified graphene oxide (GO) for electrodialysis and fuel cell applications. GO was modified with silica (fGO) using APTEOS which involves an epoxide ring opening reaction. The incorporation of silica particles within the GO flakes is characterized by TEM, EDX, XRD and FTIR while thermal stability is measured by TGA. Furthermore the successful development of the membrane is done by incorporating fGO within quaternized polyethyleneimine (PEI) and poly(vinyl alcohol) by a solution casting method followed by cross linking. The dispersibility of the silica modified graphene oxide is found to be very good within the polymer matrix. Membranes of various fGO content i.e. 1, 2, and 5 wt% within the PEI matrix have been synthesized. The surface morphology and structural analysis of the membranes were done using AFM, FTIR, XRD and 1H NMR. Thermo mechanical analysis of the membranes was done using TGA, DSC and UTM. Physicochemical and electrochemical analysis of the AEM were performed to quantify the ability for electro-membrane processes. The fGO-PEI-2 membrane shows excellent electrochemical properties with comparable stability among the membranes. Furthermore the applicability of AEMs has been analyzed towards electrodialysis and fuel cell application. fGO-PEI-2 membrane show great potential for electrodialysis and fuel cell application.

Synthesis of highly stable and high water retentive functionalized biopolymer-graphene oxide modified cation exchange membranes

Usage of polymer electrolyte membranes in energy based devices is substituting the conventional electrolytes. Herein, we have synthesized a PEM based biopolymer functionalized with silica modified GO and PVA. GO has been modified in two steps to synthesize silica grafted sulfonated GO. The functionalization of chitosan has been performed using 1,3-propane sultone after deacetylation. Furthermore, PVA has been used as a polymer matrix because PVA possesses good film forming property with mechanical stability. Different weight% (1, 2 and 5) of modified GO has been incorporated into the chitosan matrix. The prepared PEMs have been subjected to different types of characterization such as structural, thermal, mechanical and electrochemical characterization. The nano-hybrid membranes show significant increment in electrochemical properties. MGO–SCH-5 membrane shows a proton conductivity of 6.77 × 10−2 S cm−1, which increases to 11.2 × 10−2 S cm−1 at 90 °C. The thermal and mechanical stability of PEM also increases with MGO content in the sulfonated chitosan. The elastic modulus for the MGO–SCH-5 membrane is calculated to be 21.37 MPa with 54 MPa of maximum stress. Thus, these membranes may be targeted as PEMs for higher temperature energy applications.

Amide functionalized MWNT/SPEEK composite membrane for better electrochemical performance

Nanocomposite membranes based on multiwalled carbon nanotube /SPEEK (sulfonated poly ether ether ketone) have been synthesized via simple solution casting. Prior to use CNT have been purified and grafted with carboxylic acid groups onto its walls by means of sulfuric and nitric acid. Afterwards, amidation of carboxylated CNTs (c-CNT) has been done. Amidated CNT (a-CNT) is then incorporated in SPEEK polymer matrix to synthesize nanocomposite membranes. Physicochemical, structural, thermal and mechanical characterizations are done through the respective techniques. Electric and ionic conductivities have also been evaluated. Composites membranes show the enhanced electrochemical performance with higher electric conductivity.

Synthesis and characterization of different metal oxide and GO composites for removal of toxic metal ions

ABSTRACT This manuscript deals with graphene oxide (GO) and GO–metal oxide composite for heavy metal adsorption. Metal oxide–GO composites e.g. Fe3O4–GO and Mn3O4–GO have been prepared and explored for heavy metals e.g. lead, chromium, nickel, cadmium etc. adsorption from the water. Metal oxide–GO composites have been prepared through respective techniques. The various characterizations of the nanocomposites viz. structural and thermal have been analysed by transmission electron microscopy, thermogravimetric analyser etc. Different concentration of heavy metal has been taken to examine the efficiency of composites towards adsorption. Furthermore, effect of time on adsorption has also been evaluated. Metal oxide–GO composites illustrate better results as compared to GO showing the usability of composites for heavy metal adsorption for the production of clean water.

Sodium Styrene Sulfonate-co-Methyl Methacrylate-Based Proton Conducting Membranes for Electrochemical Energy Applications

ABSTRACT The present investigation reports one-pot synthetic approach to develop cation exchange membranes (CEMs) via free radical polymerization which avoids the post functionalization step that involves use of hazardous chemicals. The CEM is composed of sodium styrene sulfonate (StSO3Na), methyl methacrylate, divinyl benzene, and polyvinyl chloride which is prepared by varying relative amount of vinyl monomers. The membranes shown improved ion-exchange capacity, water uptake, ionic conductivity, and stabilities (mechanical, chemical, and thermal). Among different CEMs, CEM-1 has shown significantly improved performance with 8.54 × 10−2S.cm−1 proton conductivity and 2.71 meq. g−1 proton exchange capacity.

Zn-MOF@SPES composite membranes: synthesis, characterization and its electrochemical performance

ABSTRACT Herein, the applicability of MOF-based composite ion exchange membranes have been explored. Series of membranes have been synthesized by varying Zn-MOF content in SPES matrix. Number of spectroscopic techniques were used to characterize the successful synthesis of Zn-MOF and composite membranes. Physicochemical properties of composite membranes have been evaluated and observed to be enhanced. Composite membranes have been subjected to salt removal efficiency through electrodialysis, and observed that Z-2 membrane shows best flux and salt removal efficiency than others, which were 1.72 molm−2h−1 and 1.0 kWhkg−1 respectively with superior electro-chemical performance.

Synthesis and characterization of aluminium modified graphene oxide: an approach towards defluoridation of potable water

Abstract An approach towards the synthesis of aluminum modified graphene oxide (GO) has been studied in the present manuscript. Graphene oxide has been modified by the aluminum sulfate followed by alkalization to synthesized Al-GO composite. GO and Al-GO composite has been characterization by the means of different techniques i.e. XRD, FT-IR, FT-Raman, TEM, SEM, TGA and elemental mapping. Analysis confirmed the formation of GO and Al-GO composite. The prepared GO composite has been checked for the removal of fluoride from the potable water with different initial concentration of fluoride ions. Composite shows it’s effectiveness for the removal of fluoride throughout the pH range. The maximum adsorption capacity and Langmuir constant determined for the adsorbent dose of 1 g L−1 are found to be 38.31 mg g−1 and 0.5252 L mg−1 respectively.GRAPHICAL ABSTRACT Graphical Abstract