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Author

M. Shamsuzzoha

Bio: M. Shamsuzzoha is an academic researcher from University of Alabama. The author has contributed to research in topics: Nanoparticle & Transmission electron microscopy. The author has an hindex of 10, co-authored 40 publications receiving 507 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, polyalcohol reduction of platinum acetylacetonate, using oleylamine as a capping agent, was used to obtain well dispersed Pt nanoparticles with controlled size and narrow size distribution.

114 citations

Journal ArticleDOI
TL;DR: In this article, the fabrication of nanometer scale ordered arrays of magnetic cylindrical nanoparticles with low aspect ratio (height/radius a=0.2-7) and ultra high uniformity is described.
Abstract: We report the fabrication of nanometer scale ordered arrays of magnetic cylindrical nanoparticles with low aspect ratio (height/radius a=0.2–7) and ultrahigh uniformity. Anodization and electrochemical deposition are employed for template synthesis and metal particle growth, respectively. Particle uniformity is achieved by an electrodeposition scheme, utilizing pulse reverse voltage wave forms to control nucleation and growth of the particles. The resulting nanoparticles are polycrystalline and grains are randomly oriented. The magnetic properties of the array are dominated by particle shape and by interparticle magnetostatic interactions. A very clear transition of the anisotropy from perpendicular to in plane is observed at an aspect ratio a of about two. The arrays exhibit good thermal stability, demonstrating a great potential of these structures as future recording media in a patterned scheme. The pulse reverse electrodeposition technique shows great promise for the synthesis of nanostructures of var...

95 citations

Journal ArticleDOI
TL;DR: FCC PtRu nanoparticles with narrow size distribution were prepared by polyalcohol reduction of platinum acetylacetonate and ruthenium acetylaconate in diphenyl ether, using oleylamine as the capping agent as discussed by the authors.
Abstract: FCC PtRu nanoparticles with narrow size distribution were prepared by polyalcohol reduction of platinum acetylacetonate and ruthenium acetylacetonate in diphenyl ether, using oleylamine as the capping agent. The particle size ranged from 3.5 to 6.5 nm and was controlled by varying the amount of capping agent added in the synthesis. Adjusting the stoichiometric ratio of introduced Pt and Ru precursors yielded particles with different compositions. A simple fractionation was employed to narrow the size distribution of particles and nearly monodispersed particles were obtained. To activate the catalytic activity of the particles, oleylamine bound to the particle surface was removed through repeated washing of the as-prepared particles with ethanol and tetramethylammonium hydroxide (TMAOH) aqueous solution. The washed particles could be well redispersed and electrostatically stabilized in TMAOH aqueous solution and uniformly loaded on a Vulcan XC-72 carbon support. A cyclic voltammetry (CV) study revealed tha...

61 citations

Journal ArticleDOI
TL;DR: In this paper, the authors show that the area per molecule of a single C 60 molecule at zero pressure and at II c = 11.5 mN/m is too small for a single molecule and suggest 4-7.5 C 60 molecules piled on top of each other, per "monolayer".
Abstract: C 60 forms very rigid insoluble films («monolayers») at the air-water interface (collapse pressure II c =62.5 mN/m). The «area per molecule» A 0 =21.6 A 2 (at zero pressure) and A c =11.5 A 2 (at II c ) are too small for a single C 60 molecule and suggest 4-7.5 C 60 molecules piled on top of each other, per «monolayer»

47 citations

Journal ArticleDOI
Zhufang Liu1, Dwayne Reed1, Gihan Kwon1, M. Shamsuzzoha1, David E. Nikles1 
TL;DR: In this paper, carbon-supported Pt3Sn catalysts for methanol and CO oxidation were synthesized by coreduction of platinum acetylacetonate and tin acetylACetonate in high-boiling solvent, trioctylamine.
Abstract: We report a new method of preparing carbon-supported Pt3Sn nanoparticle catalysts for methanol and CO oxidation. Alloyed Pt3Sn nanoparticles with a cubic phase were synthesized by coreduction of platinum acetylacetonate and tin acetylacetonate in a high-boiling solvent, trioctylamine. Particle sizes in the range of 3.0 to 6.5 nm were controlled by varying the amount of introduced capping agents (oleylamine and oleic acid). The as-prepared particles displayed a narrow size distribution and were catalytically inactive. The ligands were removed to activate the nanoparticles for catalysis by treatment with tetramethylammonium hydroxide (TMAOH) solution. The treated Pt3Sn particles can be stabilized in TMAOH solution and finally loaded on XC-72 carbon support by physical deposition. Cyclic voltammetry and CO-stripping showed that all the Pt3Sn particles exhibited high electrocatalytic activity for methanol and CO oxidation. The size-dependent CO-stripping study indicated COads oxidation started at low potentia...

44 citations


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01 May 1993
TL;DR: Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems.
Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

29,323 citations

Journal ArticleDOI
TL;DR: In this review, the applications of MOFs with multiple active sites in synergistic organic catalysis, photocatalysis and tandem reactions are discussed and proposed mechanisms are presented in detail.
Abstract: Metal–organic frameworks (MOFs) are porous crystalline materials constructed from metal ions or clusters and multidentate organic ligands. Recently, the use of MOFs or MOF composites as catalysts for synergistic catalysis and tandem reactions has attracted increasing attention due to their tunable open metal centres, functional organic linkers, and active guest species in their pores. In this review, the applications of MOFs with multiple active sites in synergistic organic catalysis, photocatalysis and tandem reactions are discussed. These multifunctional MOFs can be categorized by the type of active centre as follows: (i) open metal centres and functional organic linkers in the MOF structure, (ii) active guest sites in the pores and active sites in the MOF structure, and (iii) bimetallic nanoparticles (NPs) on MOF supports. The types of synergistic catalysis and tandem reactions promoted by multifunctional MOFs and their proposed mechanisms are presented in detail. Here, catalytic MOFs with a single type of active site and MOFs that only serve as supports to enhance substrate adsorption are not discussed.

1,394 citations

Journal ArticleDOI
TL;DR: Density functional theory studies suggest that the enhanced catalytic activity for the core-shell nanoparticle originates from a combination of an increased availability of CO-free Pt surface sites on the Ru@Pt nanoparticles and a hydrogen-mediated low-temperature CO oxidation process that is clearly distinct from the traditional bifunctional CO oxidation mechanism.
Abstract: Most of the world’s hydrogen supply is currently obtained by reforming hydrocarbons. ‘Reformate’ hydrogen contains significant quantities of CO that poison current hydrogen fuel-cell devices. Catalysts are needed to remove CO from hydrogen through selective oxidation. Here, we report first-principles-guided synthesis of a nanoparticle catalyst comprising a Ru core covered with an approximately 1–2-monolayer-thick shell of Pt atoms. The distinct catalytic properties of these well-characterized core–shell nanoparticles were demonstrated for preferential CO oxidation in hydrogen feeds and subsequent hydrogen light-off. For H2 streams containing 1,000 p.p.m. CO, H2 light-off is complete by 30 ∘C, which is significantly better than for traditional PtRu nano-alloys (85 ∘C), monometallic mixtures of nanoparticles (93 ∘C) and pure Pt particles (170 ∘C). Density functional theory studies suggest that the enhanced catalytic activity for the core–shell nanoparticle originates from a combination of an increased availability of CO-free Pt surface sites on the Ru@Pt nanoparticles and a hydrogen-mediated low-temperature CO oxidation process that is clearly distinct from the traditional bifunctional CO oxidation mechanism. To produce hydrogen by reforming hydrocarbons, efficient catalysts capable of removing carbon monoxide are needed. This can now be achieved via a preferential oxidation mechanism using nanoparticle catalysts consisting of a ruthenium core covered with platinum.

1,111 citations

Journal ArticleDOI
TL;DR: Reduction Reaction in Polymer Electrolyte Membrane Fuel Cells: Particle Size, Shape, and Composition Manipulation and Their Impact to Activity
Abstract: Reduction Reaction in Polymer Electrolyte Membrane Fuel Cells: Particle Size, Shape, and Composition Manipulation and Their Impact to Activity Yan-Jie Wang,†,‡ Nana Zhao,‡ Baizeng Fang,† Hui Li,* Xiaotao T. Bi,*,† and Haijiang Wang* †Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC Canada V6T 1Z3 ‡Vancouver International Clean-Tech Research Institute Inc., 4475 Wayburne Drive, Burnaby, Canada V5G 4X4 Electrochemical Materials, Energy, Mining and Environment, National Research Council Canada, 4250 Wesbrook Mall, Vancouver, BC, Canada V6T 1W5

1,014 citations

Journal ArticleDOI
TL;DR: In this article, the formation of various heteronanostructures using the Frank-van der Merwe (FM), Volmer-Weber (VW), and Stranski-Krastanov (SK) growth modes is discussed.

980 citations