Bridgid N. Wanjala

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In situ real-time x-ray diffraction was used to study temperature-induced structural changes of 1-5 nm Au, Pt, and AuPt nanocatalysts supported on silicon substrates. Synchrotron-based x-ray diffraction indicates that the as-synthesized Au and Au(64)Pt(36) nanoparticles have a non-crystalline structure, while the Pt nanoparticles have the expected cubic(More)
The formation of nanosized alloys between a pair of elements, which are largely immiscible in bulk, is examined in the archetypical case of Pt and Au. Element specific resonant high-energy X-ray diffraction experiments coupled to atomic pair distribution functions analysis and computer simulations prove the formation of Pt-Au alloys in particles less than(More)
The understanding of the atomic-scale structural and chemical ordering in supported nanosized alloy particles is fundamental for achieving active catalysts by design. This report shows how such knowledge can be obtained by a combination of techniques including X-ray photoelectron spectroscopy and synchrotron radiation based X-ray fine structure absorption(More)
We report a novel core-shell-structured ternary nanocube of MnZn ferrite synthesized by controlling the reaction temperature and composition in the absence of conventionally used reducing agents. The highly monodispersed core-shell structure consists of an Fe(3)O(4) core and an MnZn Ferrite shell. The observation of a Moiré pattern indicates that the core(More)
The ability to tune the atomic-scale structural and chemical ordering in nanoalloy catalysts is essential for achieving the ultimate goal of high activity and stability of catalyst by design. This article demonstrates this ability with a ternary nanoalloy of platinum with vanadium and cobalt for oxygen reduction reaction in fuel cells. The strategy is to(More)
Structural and Electrocatalytic Properties of PtIrCo/C Catalysts for Oxygen Reduction Reaction Rameshwori Loukrakpam, Bridgid N. Wanjala, Jun Yin, Bin Fang, Jin Luo, Minhua Shao,* Lesia Protsailo, Tetsuo Kawamura, Yongsheng Chen, Valeri Petkov, and Chuan-Jian Zhong* Department of Chemistry, State University of New York at Binghamton, Binghamton, New York(More)
In situ real-time x-ray diffraction was used to study phase segregation and coarsening of Au-Pt nanoparticles supported on silica powder, and porous alumina membranes. Contrary to the expectations from the bulk phase diagram, silica supported Au-Pt nanoparticles have an alloyed structure that is preserved even after extensive annealing at temperatures as(More)
The understanding of nanoscale alloying or the phase segregation effect of alloy nanoparticles on the catalytic properties is important for a rational design of the desired catalysts for a specific reaction. This paper describes findings of an investigation into this type of structural effect for carbon-supported bimetallic gold-platinum nanoparticles as(More)
This Article describes findings of the correlation between the atomic scale structure and the electrocatalytic performance of nanoengineered PtNiFe/C catalysts treated at different temperatures for oxygen reduction reaction, aiming at providing a new fundamental insight into the role of the detailed atomic alloying and interaction structures of the(More)