Kothandaraman Ramanujam

Bio: Kothandaraman Ramanujam is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Catalysis & Chemistry. The author has an hindex of 12, co-authored 67 publications receiving 544 citations. Previous affiliations of Kothandaraman Ramanujam include Michigan State University.

DFT/TD‐DFT Studies of Metal‐Free N‐Annulated Perylene Based Organic Sensitizers for Dye‐Sensitized Solar Cells: Is Thiophene Spacer Essential for Improving the DSSC Performance?

Abstract: In this study, photo-physical properties of five N-annulated perylene (NP) based metal free organic D-π-A (donor-π-linker-acceptor) sensitizers for dye-sensitized solar cells (DSSCs) have been investigated by using density functional theory (DFT/B3LYP/6-31G (d)). These dyes contain triphenylamine (TPA) derivative linked to the NP, thiophene and 2-cyanoacetic acid as electron donor, conjugated linker and acceptor. Effect of TPA, substituted TPA and the of linker on the highest occupied molecular orbital, lowest unoccupied molecular orbital and bandgap energy of these compounds have been calculated and compared against experimental values reported. The electronic absorption spectra of these dyes are studied by time-dependent density functional theory calculations. Based on the calculations, (E)-2-cyano-3-(10-(4-(diphenylamino) phenyl)-1-(2-ethylhexyl)-1H-phenanthro [1,10,9,8] carbazol-3-yl) acrylic acid (NPS-4) is identified as best dye for the DSSCs operating with I3−/I− containing electrolyte. Furthermore, chemical hardness and reorganization energy of the dyes have been calculated and analyzed, whose values predicted the electron injection ability of the dyes and hence short-circuit current density. Although, all five dyes were capable of injecting electron into the conduction band of TiO2, the highest driving force for dye regeneration, the lowest reorganization energy and the highest open-circuit voltage of the NPS-4 makes it most suitable for the DSSC application.

Electrochemically synthesized molecularly imprinted polythiophene nanostructures as recognition elements for an aspirin-chemosensor

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.

Recent Advances in Electrocatalysts for Oxygen Reduction Reaction

Abstract: The recent advances in electrocatalysis for oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs) are thoroughly reviewed. This comprehensive Review focuses on the low- and non-platinum electrocatalysts including advanced platinum alloys, core–shell structures, palladium-based catalysts, metal oxides and chalcogenides, carbon-based non-noble metal catalysts, and metal-free catalysts. The recent development of ORR electrocatalysts with novel structures and compositions is highlighted. The understandings of the correlation between the activity and the shape, size, composition, and synthesis method are summarized. For the carbon-based materials, their performance and stability in fuel cells and comparisons with those of platinum are documented. The research directions as well as perspectives on the further development of more active and less expensive electrocatalysts are provided.

Metal–Organic Frameworks in Heterogeneous Catalysis: Recent Progress, New Trends, and Future Perspectives

Abstract: More than 95% (in volume) of all of today’s chemical products are manufactured through catalytic processes, making research into more efficient catalytic materials a thrilling and very dynamic rese...

Molecularly Imprinted Polymers

Abstract: Molecularly imprinted polymers are synthetic receptors for a targeted molecule. As such, they are analogues of the natural antibody–antigen systems. In this review, after a recounting of the early history of the general field, we specifically focus on the application of these polymers as sensors. In these applications, the polymers are paired with a reporting system, which may be electrical, electrochemical, optical, or gravimetric. The presence of the targeted molecule effects a change in the reporting agent, and a calibrated quantity of the target is recorded. In this review, we describe the imprinted polymer production processes, the techniques used for reporting, and the applications of the reported sensors. A brief survey of recent applications to gas-phase sensing is included, but the focus is primarily on the development of sensors for targets in solution. Included among the applications are those designed to detect toxic chemicals, toxins in foods, drugs, explosives, and pathogens. The application...

Nonprecious Metal Catalysts for Oxygen Reduction in Heterogeneous Aqueous Systems

Abstract: A comprehensive review of recent advances in the field of oxygen reduction electrocatalysis utilizing nonprecious metal (NPM) catalysts is presented Progress in the synthesis and characterization of pyrolyzed catalysts, based primarily on the transition metals Fe and Co with sources of N and C, is summarized Several synthetic strategies to improve the catalytic activity for the oxygen reduction reaction (ORR) are highlighted Recent work to explain the active-site structures and the ORR mechanism on pyrolyzed NPM catalysts is discussed Additionally, the recent application of Cu-based catalysts for the ORR is reviewed Suggestions and direction for future research to develop and understand NPM catalysts with enhanced ORR activity are provided

Durability Investigation of Carbon Nanotube as Catalyst Support for Proton Exchange Membrane Fuel Cell Electrode

Abstract: Abstract Electrochemical surface oxidation of carbon black Vulcan XC-72 and multiwalled carbon nanotube (MWNT) has been compared following potentiostatic treatments up to 168 h under condition simulating PEMFC cathode environment (60 °C, N2 purged 0.5 M H2SO4, and a constant potential of 0.9 V). The subsequent electrochemical characterization at different treatment time intervals suggests that MWNT is electrochemically more stable than Vulcan XC-72 with less surface oxide formation and 30% lower corrosion current under the investigated condition. As a result of high corrosion resistance, MWNT shows lower loss of Pt surface area and oxygen reduction reaction activity when used as fuel cell catalyst support.