Showing papers by "Kothandaraman Ramanujam published in 2017"
TL;DR: In this article, six new dyes based on phenothiazine conjugated to an ethynyl-pyrene moiety were synthesized and characterized, and they were fabricated using these dyes with and without a co-adsorbent, chenodeoxychloicacid.
Abstract: Six new dyes based on phenothiazine conjugated to an ethynyl-pyrene moiety are synthesized and characterized. Dye-sensitized solar cells are fabricated using these dyes with and without a co-adsorbent, chenodeoxychloicacid. Simple molecular engineering around the phenothiazine moiety enabled a maximum of 12% photoconversion efficiency with one of the dyes.
96 citations
TL;DR: In this paper, a chemosensor utilizing electro-polymerized film, as recognition element, has been devised and tested for selective determination of aspirin, which consists of molecularly imprinted polymer (MIP) recognition elements electrodeposited as polymeric nanowires on gold-coated quartz resonator.
Abstract: A chemosensor utilizing electro-polymerized film, as recognition element, has been devised and tested for selective determination of aspirin. The sensor consists of molecularly imprinted polymer (MIP) recognition elements electrodeposited as polymeric nanowires on gold-coated quartz resonator. A nanostructures were prepared by electrochemical co-polymerization of the preformed complex between the template, aspirin, the functional monomers, 3-thienylboronic acid (3-TBA) and 3-thiopheneacetic acid (3-TAA), and thiophene, which was employed as a cross-linker. This nanostructure upon leaching aspirin serve as MIP. Polymerizations were performed in acetonitrile (MIP-org) as well as a micelle-forming medium (MIP-mic). For MIP nanowire (MIP-ano) synthesis, sacrificial alumina templates were used during electro-polymerization in acetonitrile. Scanning electron microscope studies revealed compactly arranged polythiophene nanowires of uniform thickness in MIP-ano film, and MIP-mic film produced aggregated micron sized polymer structures. Density functional theoretical studies indicated a stable hydrogen bond-based complexation of aspirin by 3-TBA and 3-TAA in the pre-polymerization mixture implying that the MIP film thus prepared could selectively rebind the aspirin template. The MIP-ano-based chemosensor was sensitive towards aspirin (0.5–10 mM), over clinically relevant range (0.15–0.5 mM) under optimized FIA conditions. The sensitivity (20.62 Hz/mM) of the MIP-ano was eight and fifteen times higher than the MIP-mic (2.80 Hz/mM) and MIP-org (1.10 Hz/mM). Notably, the sensor selectively discriminates aspirin from structurally or functionally related interferants and metabolites, such as, salicylic acid, acetylsalicyloyl chloride and ibuprofen.
24 citations
Abstract: In this work, two 2, 5-disubstituted and three 2, 3, 5-trisubstituted thiophene-based organic dyes have been investigated using the density functional theory Although substitution at the 3-position of thiophene ring may retard the back electron transfer, the loss of coplanarity affected the intramolecular charge transfer The natural bond orbital (NBO) analysis of dye-(TiO2)8 cluster has been performed to study the feasibility of electron injection The highest driving force of dye regeneration, higher negative NBO value of cyanoacrylic acid (CA) attached to the (TiO2)8 cluster (CA-(TiO2)8 moiety), and reasonably higher open-circuit voltage make (E)-2-cyano-3-(5′-(4-(diphenylamino)phenyl)-[2,2′-bithiophen]-5-yl)acrylic acid (D1) to perform as an effective light harvester in dye-sensitized solar cells The outcomes of this theoretical study are in good agreement with the experimental data reported
19 citations
TL;DR: In this paper, the exchange of Li+ by Na+ in Li4-BPTC electrode during the electrochemical sodiation/desodiation was confirmed by ICP-OES and XPS studies.
16 citations
14 citations
12 citations
13 Jan 2017
TL;DR: In this paper, the authors explored the beneficial effect of D-fructose as an additive to the negative electrolyte and achieved a capacity retention of 86% and 25% at the end of the 25th cycle.
Abstract: Vanadium redox flow battery (VRFB) is an energy storage system, wherein V2+/V3+ and VO2+/VO2+ are used as negative and positive electrolyte respectively. It is well known that, V2+/V3+ redox reaction is sluggish in comparison to that of VO2+/VO2+ reaction. As the redox potential of V2+/V3+ redox-couple is more negative to that of H+/H2 redox-couple, during the V2+ formation hydrogen evolution occurs concomitantly, which affects the capacity retention of VRFB inducing redox couples concentration imbalance between the positive and negative electrolytes. In this study, we have explored the beneficial effect of D-fructose as an additive to the negative electrolyte. D-fructose (i) enhances the interfacial area of the graphite felt negative electrode-electrolyte interface by wetting, thereby the current due to V2+/V3+ redox reaction at a given overpotential, (ii) suppresses the H2 evolution at negative electrode during charging of VRFB (iii) controls the VO2+ accumulation at the positive electrolyte and (iv) chemically reduces the VO2+ arriving at negative electrode side through crossover, thereby avoiding the direct reaction between V2+ and VO2+. A capacity retention of 86 % and 25 % is achieved at the end of the 25th cycle in the presence and absence of D-fructose in the negative electrolyte, respectively. This way of in-situ redox balancing alleviates the requirement for external redox balancing of the electrolyte, and help VRFB to deliver constant capacity with cycles.
12 citations
12 citations
TL;DR: Paper-based fuel cells with high open-circuit voltages for application in powering the micro-nanosystems such as bio-sensors have been developed in this article, which employs Whatman paper as the ion conductor placed between the anode and the cathode to replace expensive ion-conducting membranes such as Nafion.
Abstract: This work deals about the development of paper-based fuel cells with high open-circuit voltages for application in powering the micro-nanosystems such as bio-sensors. The developed fuel cell employs Whatman paper as the ion conductor placed between the anode and the cathode to replace expensive ion-conducting membranes such as Nafion. A maximum open-circuit voltage of ∼2.1 V per single cell and a power output of ∼4.5 mW cm−2 at ∼6 mA cm−2 are obtained when employing 1 M NaBH4 in 20 wt% NaOH solution and 1 M VO2
+ in 2.5 M H2SO4 solution. Chronoamperometric measurement performed at 1 V indicates that the output power density varies from 6 to 1 mW cm−2 in about 100 min. The power delivered at the end of even 100 min is comparable to that of the peak power delivered by many of the micro-fuel cell systems reported in the literature.
12 citations
TL;DR: The performance of Au nanowire is better than Au-nanomaterials (heat- treated as well as non-heat-treated), Au seeds, and clusters, and the better efficiency of the nanowires when compared to that of the other reported catalysts is attributed to the presence of active facets with numerous corners, edges, and surface defects.
Abstract: A new, simple, green method for the synthesis of Au nanowires (average diameter 8 nm and several micrometers in length) using Au seeds prepared from bael gum (BG) is reported. The nanowires are characterized using UV–visible absorption spectroscopy, powder X-ray diffraction, transmission electron microscopy (TEM), and high-resolution-TEM. It is observed that the rate of the reduction process might be the decisive factor for the shape selectivity, as evident from the formation of nanowires at a particular concentration of seeds and NaOH. The polysaccharide present in BG is the active ingredient for the synthesis of Au nanowires, while the small molecules present in BG, when used alone, did not result in nanowire formation. The TEM images of the precursor to the Au nanowires suggested that new, nucleated particles align in a linear manner and fuse with one another, resulting in the nanowire. The linear fusion of the newly nucleated particles could be due to the lack of adequate protecting agent and the pres...
12 citations
TL;DR: In this article, an Iron(III) chloride-benzotriazole ( [FeCl 3 ( btaH ) 2 ] ) adduct was synthesized and demonstrated its ORR activity in alkaline medium, which primarily reduces oxygen by 4-electron reduction pathway.
TL;DR: In this article, a non-platinum metal catalyst, MnN x /C, was synthesized via the high-pressure pyrolysis route, which indicated the presence of Mn in +2 oxidation state surrounded by four N atoms.