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Tiwari, Jitendra N.,Kemp, Kingsley Christian,Nath, Krishna,Tiwari, Rajanish N.,Nam, Hong-Gil,Kim, Kwang S. American Chemical Society 2013 ACS NANO Vol.7 No.10
<P>Controlling the morphology and size of platinum nanodendrites (PtDs) is a key factor in improving their catalytic activity and stability. Here, we report the synthesis of PtDs on genomic-double-stranded-DNA/reduced-graphene-oxide (gdsDNA/rGO) by the NaBH<SUB>4</SUB> reduction of H<SUB>2</SUB>PtCl<SUB>6</SUB> in the presence of plant gdsDNA. Compared to industrially adopted catalysts (<I>i.e.</I>, state-of-the-art Pt/C catalyst, Pt/rGO, Pt<SUB>3</SUB>Co, <I>etc.</I>), the as-synthesized PtDs/gdsDNA/rGO hybrid displays very high oxygen reduction reaction (ORR) catalytic activities (much higher than the 2015 U.S. Department of Energy (DOE) target values), which are the rate-determining steps in electrochemical energy devices, in terms of onset-potential, half-wave potential, specific-activity, mass-activity, stability, and durability. Moreover, the hybrid exhibits a highly stable mass activity for the ORR over a wide pH range of 1–13. These exceptional properties would make the hybrid applicable in next-generation electrochemical energy devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2013/ancac3.2013.7.issue-10/nn4038404/production/images/medium/nn-2013-038404_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn4038404'>ACS Electronic Supporting Info</A></P>
Tiwari, Alka,Shukla, Alok,Tiwari, Diwakar,Choi, Suk Soon,Shin, Hyun-Gon,Lee, Seung-Mok The Korean Society of Industrial and Engineering C 2019 공업화학 Vol.30 No.3
The aim of this review article is to summarize the role of titanium oxide ($TiO_2$) nanomaterials in the remediation of the aquatic environment contaminated with various emerging pollutants. The advanced oxidation process led by the semiconductor $TiO_2$ is an impetus in the remediation technology. Therefore, a vast number of literature works are available in this area. Further, the role of modified $TiO_2$ or thin film materials were discussed in the review. Also, the Localized Surface Plasmon Resonance (LSPR) effect of using noble metaldoped $TiO_2$ played an interesting role in the remediation process.
( Alka Tiwari ),( Alok Shukla ),( Diwakar Tiwari ),( Suk Soon Choi ),( Hyun-gon Shin ),( Seung-mok Lee ) 한국공업화학회 2019 공업화학 Vol.30 No.3
The aim of this review article is to summarize the role of titanium oxide (TiO<sub>2</sub>) nanomaterials in the remediation of the aquatic environment contaminated with various emerging pollutants. The advanced oxidation process led by the semiconductor TiO<sub>2</sub> is an impetus in the remediation technology. Therefore, a vast number of literature works are available in this area. Further, the role of modified TiO<sub>2</sub> or thin film materials were discussed in the review. Also, the Localized Surface Plasmon Resonance (LSPR) effect of using noble metaldoped TiO<sub>2</sub> played an interesting role in the remediation process.
Alka Tiwari,Alok Shukla,Lalliansanga,Diwakar Tiwari,이승목 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.69 No.-
Novel meso-porous nanoparticles Au/TiO2 thin films were obtained by template synthesis using polyethylene glycol as filler medium. The materials were characterized by advanced analytical methods. The photocatalysts were employed for the photocatalytic degradation of tetracycline from aqueous solutions using UV-A light (λmax 330 nm). Various physico-chemical parametric studies enabled to deduce the mechanism of degradation. A significant percentage of tetracycline was mineralized by the treatment. The stability of thin film was evidenced with the repeated use of thin film. The degradation of tetracycline was proceeded predominantly by the OH radicals generated at the valance and conduction band of semiconductor.
Tiwari, Jitendra N.,Lee, Wang Geun,Sultan, Siraj,Yousuf, Muhammad,Harzandi, Ahmad M.,Vij, Varun,Kim, Kwang S. American Chemical Society 2017 ACS NANO Vol.11 No.8
<P>A key challenge in developing fuel cells is the fabrication of low-cost electrocatalysts with high activity and long durability for the two half-reactions, i.e., the methanol/ethanol oxidation reaction (MOR/EOR) and the oxygen reduction reaction (ORR). Herein, we report a conductivity-enhanced bifunctional electrocatalyst of nanoscale-coated Pt-Pd alloys on both tin-doped indium (TDI) and reduced graphene oxide (rGO), denoted as Pt-Pd@TDI/rGO. The mass activities of Pt in the Pt-Pd@TDI/rGO hybrid toward MOR, EOR, and ORR are 2590, 1500, and 2690 mA/mg, respectively. The ORR Pt specific activity and mass activity of the electrocatalyst are 17 and 28 times larger, respectively, than commercial Pt/C catalysts. All these remarkable catalytic performances are attributed to the role of TDI in enhancing the catalytic activity,by protecting Pt from oxidation as well as rapid mass/charge transfer due to the synergistic effect between surface Pt-Pd alloys and TDI/rGO.</P>
Tiwari, A.P.,Joshi, M.K.,Kim, J.I.,Unnithan, A.R.,Lee, J.,Park, C.H.,Kim, C.S. Academic Press 2016 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.476 No.-
We report for the first time a polycaprolactone-human serum albumin (PCL-HSA) membrane with bimodal structures comprised of spider-web-like nano-nets and conventional fibers via facile electro-spinning/netting (ESN) technique. Such unique controllable morphology was developed by electrospinning the blend solution of PCL (8wt% in HFIP 1,1,1,3,3,3,-Hexafluoro-2-propanol) and HSA (10wt% deionized water). The phase separation during electrospinning caused the formation of bimodal structure. Various processing factors such as applied voltage, feeding rate, and distance between nozzle tip and collector were found responsible for the formation and distribution of the nano-nets throughout the nanofibrous mesh. Field emission electron microscopy (FE-SEM) confirmed that the nano-nets were composed of interlinked nanowires with an ultrathin diameter (10-30nm). When compared with a pure PCL membrane, the membrane containing nano-nets was shown to have better support for cellular activities as determined by cell viability and attachment assays. These results revealed that the blending of albumin, a hydrophilic biomolecule, with PCL, a hydrophobic polymer, proves to be an outstanding approach to developing membranes with controlled spider-web-like nano-nets for tissue engineering.
Engineering a novel bilayer membrane for bone defects regeneration
Tiwari, A.P.,Joshi, M.K.,Maharjan, B.,Ko, S.W.,Kim, J.I.,Park, C.H.,Kim, C.S. North-Holland 2016 Materials letters Vol.180 No.-
We report the fabrication of a novel bilayer scaffold as a barrier membrane via modified-solvent casting and evaporation technique for the regeneration of bone defects. The blended solution of polycaprolactone (PCL) and calcium carbonate (CaCO<SUB>3</SUB>) was treated with hydrochloric acid (HCL), which resulted in the in situ formation of carbon dioxide (CO<SUB>2</SUB>) and water. This led to the phase separation between the PCL and calcium-based compounds and subsequently to the formation of a bilayer membrane. Surface morphology, surface wettability, and energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the formation of a bilayered construct with a PCL-rich thin layer on the upper surface and a calcium-rich porous layer on the lower surface. From the FE-SEM images, the PC30 membrane showed a smooth upper layer with pores less than 10@?m diameter, whereas the lower layer contained many interconnected larger pores up to 1000@?m diameter in addition to the visibly identified macrovoids. The cell adhesion assay showed that both surfaces of the membrane responded well to the cells. In addition, the upper surface prevented the down-growth of the fibroblasts. The initial results suggest a new strategy for the fabrication of the bilayer membrane for regenerative medicine.
Al based ultra-fine eutectic with high room temperature plasticity and elevated temperature strength
Tiwary, C.S.,Kashyap, S.,Kim, D.H.,Chattopadhyay, K. Elsevier Sequoia 2015 Materials science & engineering. properties, micro Vol.639 No.-
Developments of aluminum alloys that can retain strength at and above 250<SUP>o</SUP>C present a significant challenge. In this paper we report an ultrafine scale Al-Fe-Ni eutectic alloy with less than 3.5at% transition metals that exhibits room temperature ultimate tensile strength of ~400 MPa with a tensile ductility of 6-8%. The yield stress under compression at 300<SUP>o</SUP>C was found to be 150 MPa. We attribute it to the refinement of the microstructure that is achieved by suction casting in copper mold. The characterization using scanning and transmission electron microscopy (SEM and TEM) reveals an unique composite structure that contains the Al-Al<SUB>3</SUB>Ni rod eutectic with spacing of ~90nm enveloped by a lamellar eutectic of Al-Al<SUB>9</SUB>FeNi (~140nm). Observation of subsurface deformation under Vickers indentation using bonded interface technique reveals the presence of extensive shear banding during deformation that is responsible for the origin of ductility. The dislocation configuration in Al-Al<SUB>3</SUB>Ni eutectic colony indicates accommodation of plasticity in α-Al with dislocation accumulation at the α-Al/Al<SUB>3</SUB>Ni interface boundaries. In contrast the dislocation activities in the intermetallic lamellae are limited and contain set of planner dislocations across the plates. We present a detailed analysis of the fracture surface to rationalize the origin of the high strength and ductility in this class of potentially promising cast alloy.