Efficient electro‐oxidation of formic acid, methanol, and ethanol is challenging owing to the multiple chemical reaction steps required to accomplish full oxidation to CO2. Herein, a ternary CoPtAu ...nanoparticle catalyst system is reported in which Co and Pt form an intermetallic L10‐structure and Au segregates on the surface to alloy with Pt. The L10‐structure stabilizes Co and significantly enhances the catalysis of the PtAu surface towards electro‐oxidation of ethanol, methanol, and formic acid, with mass activities of 1.55 A/mgPt, 1.49 A/mgPt, and 11.97 A/mgPt, respectively in 0.1 m HClO4. The L10‐CoPtAu catalyst is also stable, with negligible degradation in mass activities and no obvious Co/Pt/Au composition changes after 10 000 potential cycles. The in situ surface‐enhanced infrared absorption spectroscopy study indicates that the ternary catalyst activates the C−C bond more efficiently for ethanol oxidation.
Ternary monodisperse CoPtAu nanoparticles are shown to be an efficient electro‐oxidation catalyst to cleave the C−C bond of ethanol. It favors a complete oxidation to CO2.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
The pathogenic yeast, Candida albicans, and other microbes must be able to handle drastic changes in nutrient availability within the human host. Copper, iron, and phosphate are essential ...micronutrients for microbes that are sequestered by the human host as nutritional immunity; yet high copper levels are employed by macrophages to induce toxic oxidative stress. Grf10 is a transcription factor important for regulating genes involved in morphogenesis (filamentation, chlamydospore formation) and metabolism (adenylate biosynthesis, 1-carbon metabolism). The grf10Δ mutant exhibited resistance to excess copper in a gene dosage-dependent manner but grew the same as the wild type in response to other metals (calcium, cobalt, iron, manganese, and zinc). Point mutations in the conserved residues D302 and E305, within a protein interaction region, conferred resistance to high copper and induced hyphal formation similar to strains with the null allele. The grf10Δ mutant misregulated genes involved with copper, iron, and phosphate uptake in YPD medium and mounted a normal transcriptional response to high copper. The mutant accumulated lower levels of magnesium and phosphorus, suggesting that copper resistance is linked to phosphate metabolism. Our results highlight new roles for Grf10 in copper and phosphate homeostasis in C. albicans and underscore the fundamental role of Grf10 in connecting these with cell survival.
Homogeneous platinum alloy nanoparticles (NPs) are of great interest to the electrocatalytic community for potential use in various fuel cell electrodes. Increasing the surface area available per ...unit mass by decreasing the size of NPs while maintaining or improving activity is one of the key tasks of fuel cell catalysis. Achieving both in a synthesis of multielement NPs is still a challenging workup. In this investigation, we report the use of glycine as a size control agent to make ultrasmall homogeneous trimetallic PtNiCu NPs within 2-5 nm range. The mechanistic roles of dimethyl formamide (DMF), formaldehyde, water, and glycine are explored to understand the formation of these small NPs. Interestingly, it was observed that these PtNiCu NPs exhibited substantially enhanced mass activities toward the electro-oxidation of ethanol in comparison to commercial Pt black.
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IJS, KILJ, NUK, PNG, UL, UM
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5.
A diverse view of science to catalyse change Urbina-Blanco, César A; Jilani, Safia Z; Speight, Isaiah R ...
Chemical science (Cambridge),
09/2020, Volume:
11, Issue:
34
Journal Article
Peer reviewed
Open access
Valuing diversity leads to scientific excellence, the progress of science and, most importantly, it is simply the right thing to do. We can value diversity not only in words, but also in actions.
...Valuing diversity leads to scientific excellence, the progress of science and, most importantly, it is simply the right thing to do. We must value diversity not only in words, but also in actions.
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IJS, KILJ, NUK, UL, UM, UPUK
Efficient electro‐oxidation of formic acid, methanol, and ethanol is challenging owing to the multiple chemical reaction steps required to accomplish full oxidation to CO2. Herein, a ternary CoPtAu ...nanoparticle catalyst system is reported in which Co and Pt form an intermetallic L10‐structure and Au segregates on the surface to alloy with Pt. The L10‐structure stabilizes Co and significantly enhances the catalysis of the PtAu surface towards electro‐oxidation of ethanol, methanol, and formic acid, with mass activities of 1.55 A/mgPt, 1.49 A/mgPt, and 11.97 A/mgPt, respectively in 0.1 m HClO4. The L10‐CoPtAu catalyst is also stable, with negligible degradation in mass activities and no obvious Co/Pt/Au composition changes after 10 000 potential cycles. The in situ surface‐enhanced infrared absorption spectroscopy study indicates that the ternary catalyst activates the C−C bond more efficiently for ethanol oxidation.
Hinfort mit dem Alkohol! Es wird gezeigt, dass ternäre monodisperse CoPtAu‐Nanopartikel effiziente Elektrooxidationskatalysatoren für den Bruch der C‐C‐Bindung in Ethanol sind. Das System bevorzugt dabei die vollständige Oxidation zu CO2.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A Diverse View of Science to Catalyse Change Urbina‐Blanco, César A.; Jilani, Safia Z.; Speight, Isaiah R. ...
Angewandte Chemie,
October 12, 2020, Volume:
132, Issue:
42
Journal Article
A novel hexavanadate–organic hybrid material of the formula NH42V6(µ2-O)6(O)4(PDC)6 (PDC = 2,6-pyridinedicarboxylate) has been prepared in dilute nitric acid under hydrothermal reaction conditions. ...The product was characterized by single crystal and powder X-ray diffraction, FTIR, UV–Vis, Raman, and thermogravimetric analyses in the solid state, and small angle X-ray scattering, ESI-MS, NMR (1H, 13C, 51V), and Raman spectroscopic techniques in aqueous solution. The crystal structure revealed a rare structure type in vanadium chemistry which crystallizes in the monoclinic space group P21/n and consists of a cyclic polyoxovanadate core with edge-capped tetrahedral and octahedral vanadium centers. The “hollow” polyoxovanadate is stabilized by a PDC ligand on each metal center, and ammonium ions charge balance the anionic core and form hydrogen bonding interactions with the hexavanadate units. Solution-state studies showed that the structural unit observed in the solid state hydrolyzes upon dissolution in water, resulting in a symmetric dimer bearing similar ligand sets. Catalytic experiments on the photodecomposition of crystal violet, rhodamine B, methylene blue, and rhodamine 6G showed ≥93% degradation of the dyes under UV light irradiation upon addition of the vanadium complex.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A novel hexavanadate–organic hybrid material of the formula NH42V6(µ2-O)6(O)4(PDC)6 (PDC = 2,6-pyridinedicarboxylate) has been prepared in dilute nitric acid under hydrothermal reaction conditions. ...The product was characterized by single crystal and powder X-ray diffraction, FTIR, UV–Vis, Raman, and thermogravimetric analyses in the solid state, and small angle X-ray scattering, ESI-MS, NMR (1H, 13C, 51V), and Raman spectroscopic techniques in aqueous solution. The crystal structure revealed a rare structure type in vanadium chemistry which crystallizes in the monoclinic space group P21/n and consists of a cyclic polyoxovanadate core with edge-capped tetrahedral and octahedral vanadium centers. The “hollow” polyoxovanadate is stabilized by a PDC ligand on each metal center, and ammonium ions charge balance the anionic core and form hydrogen bonding interactions with the hexavanadate units. Solution-state studies showed that the structural unit observed in the solid state hydrolyzes upon dissolution in water, resulting in a symmetric dimer bearing similar ligand sets. Finally, catalytic experiments on the photodecomposition of crystal violet, rhodamine B, methylene blue, and rhodamine 6G showed ≥93% degradation of the dyes under UV light irradiation upon addition of the vanadium complex.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In efforts to find renewable and sustainable alternatives to gasoline in transportation vehicles, scientists have been studying the design and use of fuel cells. In a fuel cell, a fuel undergoes a ...reaction that generates electricity, and that electricity can power a vehicle. One possible solution is the ethanol fuel cell where ethanol can be converted into electricity by using nanoparticle (NP) electrocatalysts. A few issues in ethanol fuel cells include: having a catalyst with less Pt in it as Pt is costly and nonrenewable, having a catalyst with a low onset potential to improve efficiency, and having a catalyst that is selective to the full oxidation of ethanol, which also improves efficiency. In my research, I have synthesized, purified, and characterized PtNiCu NPs for the use of studying the ethanol electrooxidation reaction (EOR) in ethanol fuel cells. To better understand the mechanism of the reaction, I have studied the products generated from the reaction to determine if full vs. partial oxidation is preferred by using an in-situ electrochemical nuclear magnetic resonance (NMR) technique that I helped develop. I also investigated part of the mechanism of the reaction using in-situ electrochemical infrared (IR) to better understand how Ni improves the EOR reaction. I also investigated part of the mechanism of EOR for a collaborator’s catalyst using in-situ electrochemical IR. The last part of my dissertation also highlights some of my contributions to advancing the scientific community beyond lab research through science communication, leadership, and advocacy.
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