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Synthesis of mixed phase anatase-TiO<sub>2</sub>(B) by a simple wet chemical method
Parayil, S.K.,Kibombo, H.S.,Mahoney, L.,Wu, C.M.,Yoon, M.,Koodali, R.T. North-Holland 2013 Materials letters Vol.95 No.-
A photoactive mixed phase, anatase-TiO<SUB>2</SUB>(B) was synthesized from a mixture of trititanate nanotube and urea at relatively mild conditions. This material exhibited enhanced photocatalytic hydrogen generation under simulated solar irradiation. The enhancement was credited to the presence of mixed phases of anatase and TiO<SUB>2</SUB>(B) that minimized charge-carrier recombination. The results validate the superior performance of anatase-TiO<SUB>2</SUB>(B) compared to anatase or TiO<SUB>2</SUB>(B) alone. Such mixed phase materials may also be applicable for solar assisted degradation of persistent organic pollutants and solar energy conversion devices.
Parayil, S.K.,Razzaq, A.,Park, S.M.,Kim, H.R.,Grimes, C.A.,In, S.I. Elsevier 2015 Applied Catalysis A Vol.498 No.-
Carbon and nitrogen co-doped sodium titanate nanotubes (C,N-TNT) active under simulated solar light are synthesized by a simple two-step process comprising an alkaline hydrothermal technique followed by calcination. Different samples of C,N-TNT with varied dopant concentrations are achieved by changing the amount of urea as a nitrogen and carbon dopants. The photocatalysts are characterized using numerous experimental techniques, and under simulated solar light investigated for the photocatalytic conversion of CO<SUB>2</SUB> and water vapor to CH<SUB>4</SUB>. The C,N-TNT sample with an intermediate doping concentration yields the maximum methane yield of 9.75μmol/gh. The key factors contributing in the improvement of photocatalyst performance includes light absorption, surface area and Na<SUP>+</SUP> ions concentration in TNT acting as CO<SUB>2</SUB> adsorption site and photogenerated electrons recombination centers. The higher doping levels results in lower specific surface areas leading to decrease in photocatalyst performance. Our results suggest co-doping of nanostructured photocatalysts is an excellent pathway for improving textural and photocatalytic properties for the respective application domain.
Highly fluorescent peptide nanoribbon impregnated with Sn-porphyrin as a potent DNA sensor.
Parayil, Sreenivasan Koliyat,Lee, Jooran,Yoon, Minjoong Royal Society of Chemistry 2013 Photochemical & photobiological sciences Vol.12 No.5
<P>Highly fluorescent and thermo-stable peptide nanoribbons (PNRs) were fabricated by solvothermal self-assembly of a single peptide (D,D-diphenyl alanine peptides) with Sn-porphyrin (trans-dihydroxo[5,10,15,20-tetrakis(p-tolyl)porphyrinato] Sn(IV) (SnTTP(OH)2)). The structural characterization of the as-prepared nanoribbons was performed by transmitting electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM), FT-IR and Raman spectroscopy, indicating that the lipophilic Sn-porphyrins are impregnated into the porous surface formed in the process of nanoribbon formation through intermolecular hydrogen bonding of the peptide main chains. Consequently the Sn-porphyrin-impregnated peptide nanoribbons (Sn-porphyrin-PNRs) exhibited typical UV-visible absorption spectrum of the monomer porphyrin with a red shifted Q-band, and their fluorescence quantum yield was observed to be enhanced compared to that of free Sn-porphyrin. Interestingly the fluorescence intensity and lifetimes of Sn-porphyrin-PNRs were selectively affected upon interaction with nucleotide base sequences of DNA while those of free Sn-porphyrins were not affected by binding with any of the DNA studied, indicating that DNA-induced changes in the fluorescence properties of Sn-porphyrin-PNRs are due to interaction between DNA and the PNR scaffold. These results imply that Sn-porphyrin-PNR will be useful as a potent fluorescent protein analogue and as a biocompatible DNA sensor.</P>
Formation of biotinylated trititanate nanofibers (BioTNFs): potent optical probes for protein
Parayil, Sreenivasan Koliyat,Yoon, Minjoong Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.8
<P>The trititanate (H<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB>) nanofibers (TNFs) prepared by a hydrothermal method, which are photocatalytically inactive, have been biotinylated by their reaction with <I>N</I>-hydroxysuccinimidobiotin through aminosilinization with 3-aminopropyl triethoxysilane (APTS). Surface morphology and covalent binding of the biotinylated TNFs (BioTNFs) are identified by XRD, SEM, TEM and FT-IR measurements. The BioTNFs are observed to form a charge transfer state as proved by XPS and the diffuse reflectance UV-visible absorption spectra, exhibiting stronger surface emission than free TNFs or TiO<SUB>2</SUB> quantum dots. The strong fluorescence emission of BioTNFs is found to be significantly quenched upon interaction with streptavidin due to photoinduced electron transfer from the charge transfer state of the BioTNFs to streptavidin. On the other hand, the fluorescence of Cy3 was observed to be enhanced upon binding Cy3-streptavidin with BioTNFs, indicating that BioTNFs are good immobilizers of protein. These results suggest that BioTNFs are potent optical probe materials for protein analysis.</P> <P>Graphic Abstract</P><P>The newly synthesized biotinylated trititanate nanofibers exhibit strong fluorescence emission sensitive to interaction with protein as potent optical protein-probes. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0jm02475a'> </P>
Photo-catalytic CO<sub>2</sub> reduction of C, N co-doped sodium titanate nanotube
( Sreenivasan Koliyat Parayil ),박승민,( Abdul Razzaq ),인수일 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1
We report on the synthesis of C, N co-doped sodium titanate nanotube (C, N-TNT) by a hydrothermal method and calcination treatment. Na<sup>+</sup>- TNT was calcined to dope C and N from Urea. The presence of dopant ions are confirmed by X-ray Photoelectron Spectroscopy (XPS), Diffuse Reflectance Uv-vis spectroscopy (Uv-vis DRS) and Raman scattering. The photocatalytic effects of C, N-TNT are identified by methylene blue degradation and CO<sub>2</sub> reduction test under simulated solar light irradiation. The C,N-TNT10 (Urea/TiO<sub>2</sub> =10) showed highest conversion efficiency for photocatalytic dye degradation and CO<sub>2</sub> reduction.
Alternating and Merged Droplets in a Double T-junction Microchannel
Harish Palani Naga Surya,Sajeesh Parayil,Utsab Banerjee,Subhash Chander,Ashis Kumar Sen 한국바이오칩학회 2015 BioChip Journal Vol.9 No.1
In this work, we report experimental andnumerical studies of alternating and merged dropletsin a double T-junction microchannel. The microchanneldevice is fabricated using PDMS substrate and experimentsare performed with mineral oil with surfactantas the continuous phase and aqueous glycerol asthe discrete phase. Based on the flow rate fraction φand Capillary number Ca, four different flow regimesare identified: merging, stable alternating droplets, alternatingdroplets with transition and laminar. A numericalmodel that employs volume-of-fluid formulationsis used to predict the alternating droplet generationprocess. In the stable alternating droplet regime,the effect of the discrete phase flow rate ratio α on thedroplet diameter ratio β is experimentally studied andcompared with that predicted from the simulations. Itis observed that the droplet diameter ratio β increaseslinearly with increase in the flow rate ratio α and agood match between experiments and simulations isobserved. The diameters of droplets at different Capillarynumbers Ca generated using single and doubleT-junction microchannels are compared and it is observedthat, at low Ca, the double T-junction generateslarger droplets as compared to single T-junction. In merged droplet regime, the effect of the continuousphase flow rate Qc and discrete phase viscosity μd ondiameter dm and interdistance between the droplets λof the merged droplets are studied. It is observed thatthe merged droplet diameter dm is reduced and interdistancebetween the droplets λ increases with increasein the continuous phase flow rate Qc. As the viscosityof the discrete phase μd increases, the diameter dm andinterdistance between the droplets λ of the mergeddroplets decreases.