Controlled Synthesis of a Hexagonal-Shaped NiO Nanocatalyst with Highly Reactive Facets {1 1 0} and Its Catalytic Activity

Patra, Astam K.,Kundu, Sudipta K.,Kim, Dukjoon,Bhaumik, Asim Wiley Blackwell (John Wiley Sons) 2015 ChemCatChem Vol.7 No.5

Highly robust magnetically recoverable Ag/Fe₂O₃ nanocatalyst for chemoselective hydrogenation of nitroarenes in water

Patra, Astam K.,Vo, Nhat Tri,Kim, Dukjoon Elsevier 2017 Applied Catalysis A Vol.538 No.-

<P><B>Abstract</B></P> <P>This work reports on additive-free Ag nanoparticles (4–6nm) deposition on magnetic α-Fe<SUB>2</SUB>O<SUB>3</SUB> nanocrystals surface by the slow reduction of AgNO<SUB>3</SUB> with NaBH<SUB>4</SUB> in aqueous medium. The EDS analysis revealed that the new materials contain 3.93wt% of Ag nanoparticle on the surface of α-Fe<SUB>2</SUB>O<SUB>3</SUB> which are the active suite for hydrogenation reaction. The Ag/Fe<SUB>2</SUB>O<SUB>3</SUB> nanocatalysts exhibited good catalytic ability toward chemoselective hydrogenation of nitroarenes in water. LC–MS study suggested that the catalytic reaction pathway is NO<SUB>2</SUB>, NHOH, NH<SUB>2</SUB> and certainly skips the nitrosoarene intermediate step. The nanocatalysts are very efficient in the hydrogenation of nitroarenes tolerating H, Br, I, OH, OCH<SUB>3</SUB>, COOH and CONH<SUB>2</SUB> functional groups. The nanocatalysts were separated by external magnet and recycled in aqueous medium which offer environmentally and safe approach to this hydrogenation reaction. The catalyst was tested up to 10 recycles and showed no significant loss of catalytic activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly efficient Ag nanoparticles incorporated magnetic α-Fe<SUB>2</SUB>O<SUB>3</SUB> nanocatalyst were developed by simple method. </LI> <LI> 4–6nm Ag nanoparticles on the surface of α-Fe<SUB>2</SUB>O<SUB>3</SUB> are the active suite for the high catalytic activity. </LI> <LI> LC–MS study suggested that the catalytic reaction pathway is NO<SUB>2</SUB>, NHOH, NH<SUB>2</SUB> and certainly skips the nitrosoarene intermediate step. </LI> <LI> The nanocatalyst are very efficient in the hydrogenation of nitroarenes tolerating H, Br, I, OH, OCH<SUB>3</SUB>, COOH, and CONH<SUB>2</SUB> functional groups in water. </LI> <LI> High catalytic activity and excellent recyclability and can be separated by external magnet and no significant loss of catalytic activity after 10 recycles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced photocatalytic performance of novel self-assembled floral β-Ga2O3 nanorods

K. Girija,S. Thirumalairajan,Astam K. Patra,D. Mangalaraj,N. Ponpandian,C. Viswanathan 한국물리학회 2013 Current Applied Physics Vol.13 No.4

Self-assembled monoclinic phase of novel floral b-Ga2O3 nanorods were prepared using reflux condensation method by controlled precipitation of metal cations with urea. The structural and morphological properties were investigated by X-ray powder diffraction, Raman spectroscopy and Scanning electron microscope. Single-crystalline nanorods with size 100 nm involved in the selfassembly process to form flowery pattern have diameter w1 mm with surface area 40.8 m2/g confirmed from transmission electron microscope and BrunauereEmmetteTeller analysis. The band gap energy of 4.59 eV was evaluated from the UVevis diffuse reflectance spectrum and the photoluminescence spectrum displayed the characteristic luminescence and blue-light emission peaks. Further, the photocatalytic activity of novel b-Ga2O3 floral nanorods towards the photodegradation of Rhodamine B in aqueous solution under ultra violet light irradiation showed better photocatalytic activity than the commercial photocatalyst Degussa P25 TiO2.

Synthesis of Hollow Doughnut Shape Mesoporous Silica Nanoparticle: A Case of Self-Assembly Composite Templates

Vo, Nhat Tri,Patra, Astam K.,Kim, Dukjoon American Chemical Society 2018 Langmuir Vol.34 No.13

<P>The new class of silica nanoparticles with unprecedented structural morphology is synthesized by hydrolysis of tetraethyl orthosilicate (TEOS) in the presence of cetyltrimethylammonium bromide (CTAB), <SMALL>L</SMALL>-arginine, and ammonium metatungstate (AMT) composite template, all in aqueous ethanol. The morphology of the synthesized mesoporous silica nanoparticles (MSNs) can be tuned from a spherical to a hollow doughnut shape through a hollow sphere by controlling the concentration of AMT in the composite template. The formation mechanism of the hollow doughnut shaped MSNs (hd-MSNs) is well-explored by means of zeta potential, high-resolution transmission electron microscopy (HRTEM) with elemental mapping analysis, and X-ray photoelectron spectroscopy. The unique structure of the hd-MSNs as well as their high thermal and mechanical stability is expected to result in their application in shape-selective catalysis, drug-delivery, and sensors.</P> [FIG OMISSION]</BR>

Chemically modified poly(arylene ether ketone)s with pendant imidazolium groups: Anion exchange membranes for alkaline fuel cells

Tuan, Cao Manh,Patra, Astam K.,Kim, Dukjoon Elsevier 2018 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.43 No.9

<P><B>Abstract</B></P> <P>Anion exchange membranes (AEMs) with high stability are prepared for alkaline fuel cells using poly(arylene ether ketone)s (PAEKs) containing pendant imidazolium groups (via a direct step-growth polycondensation reaction). <SUP>1</SUP>H nuclear magnetic resonance spectroscopy (<SUP>1</SUP>H NMR) and Fourier transform infrared (FT-IR) spectroscopy are used to analyze the chemical structure of the prepared PAEK membranes. The anion conductivity, water uptake and swelling ratio, thermal, mechanical, and chemical stability of these membranes are investigated for PAEK membranes with different 1-(3-aminopropyl)imidazole (API) molar ratios (PAEK-API-x) in details. The anion conductivity of PAEK-API-x membranes increases with increasing molar ratio of API. The membrane with API 1.5 equiv. displays the highest anion conductivity (0.0053–0.0531 S cm<SUP>−1</SUP> from 30 °C to 80 °C). All prepared membranes show good chemical and mechanical stability as well as thermal stability up to 250 °C. This high anion conductivity with good thermal, mechanical, and chemical stability of the membrane show potential advantage to meet the demands for AEMs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PAEK membranes with pendant imidazolium group was synthesized for AEMFC. </LI> <LI> Membrane properties were significantly affected by the amount of imidazolium group. </LI> <LI> Some membranes exhibited higher conductivity than commercial ones. </LI> <LI> All PAEK membranes showed excellent thermal, mechanical, and chemical stability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Hollow doughnut shaped mesoporous silica nanoparticles for reduction of the thermal expansion coefficient of poly(ether sulfone) films

Vo, Nhat Tri,Patra, Astam K.,Kim, Dukjoon The Royal Society of Chemistry 2018 New journal of chemistry Vol.42 No.7

<P>A decrease in the coefficient of thermal expansion of poly(ether sulfone) films is achieved through the incorporation of hollow doughnut shaped mesoporous silica nanoparticles (hd-MSNs). A new class of silica nanoparticles with an unprecedented structural morphology is synthesized by hydrolysis of tetraethyl orthosilicate (TEOS) in the presence of cetyltrimethylammonium bromide (CTAB), l-arginine, and ammonium metatungstate (AMT) composite templates, all in aqueous ethanol. 46.1% and 48.0% decreases in the coefficient of thermal expansion (CTE) of poly(ether sulfone) films are observed in the range of 30-90 °C and 30-150 °C, respectively, when 2.0 wt% of hd-MSNs are loaded. Furthermore, the small size (<50 nm diameter) of doughnut shaped mesoporous silica nanoparticles helps to decrease light scattering, and thus maintains the high transmittance of the nanocomposite films. The effect of the hd-MSN was also investigated on both the thermal and mechanical stability. We expect that the hd-MSN synthesized in this study can be used as a promising filler to improve the thermal and mechanical stability of the PES substrate without losing its optical transparency.</P>