Topic
Oxygen
About: Oxygen is a research topic. Over the lifetime, 48149 publications have been published within this topic receiving 1113788 citations. The topic is also known as: O & Oxygen.
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TL;DR: In this article, a series of Fe42Pt58 nanoparticles of different compositions (x = 63, 58, 54, 42, 15, and 0) were prepared and loaded onto a glassy carbon (GC) electrode where their catalytic activities in the electroreduction of oxygen were examined and compared.
Abstract: FexPt100-x nanoparticles of different compositions (x = 63, 58, 54, 42, 15, and 0) were prepared and loaded onto a glassy carbon (GC) electrode where their catalytic activities in the electroreduction of oxygen were examined and compared. Cyclic and rotating disk voltammetric studies of the resulting FexPt100-x/GC electrodes showed that the catalytic activity for oxygen reduction exhibited a peak-shape dependence on the particle composition (x). Among the series of nanocatalysts under study, Fe42Pt58 particles showed the maximum activity for O2 reduction in terms of the reduction overpotential and current density. This was accounted for by the effects of the Fe content on the electronic structures of the Pt active sites and the resulting Pt−O interactions. Kinetic analyses showed that direct four-electron reduction of adsorbed oxygen occurred on these catalyst surfaces. Additionally, the rate constant of O2 reduction increased with increasing Pt content in the alloy particles; yet, at x ≤ 42, the rate con...
203 citations
TL;DR: In this article, the authors studied the catalytic activity of very tiny Au particles on TiO2 and found that they can prepare Au islands with controlled thicknesses from one to several monolayers.
Abstract: Very tiny Au particles on TiO2 show excellent activity and selectivity in a number of oxidation reactions. We have studied the vapor deposition of Au onto a TiO2(110) surface using XPS, LEIS, LEED and TPD and found that we can prepare Au islands with controlled thicknesses from one to several monolayers. In order to understand at the atomic level the unusual catalytic activity in oxidation reactions of this system, we have studied oxygen adsorption on Au/TiO2(110) as a function of Au island thickness, and have measured the titration of this adsorbed oxygen with CO gas to yield CO2, as function of Au island thickness, CO pressure and temperature. A hot filament was used to dose gaseous oxygen atoms. TPD results show higher O2 desorption temperatures (741 K) from ultrathin gold particles on TiO2(110) than from thicker particles (545 K). This implies that Oa bonds much more strongly to ultrathin islands of Au. Thus from Bronsted relations, ultrathin gold particles should be able to dissociatively adsorb O2 more readily than thick gold particles. Our studies of the titration reaction of oxygen adatoms with CO (to produce CO2) show that this reaction is extremely rapid at room temperature, but its rate is slightly slower for the thinnest Au islands. Thus the association reaction (COg + Oa → CO2,g) gets faster as the oxygen adsorption strength decreases, again as expected from Bronsted relations. For islands of about two atomic layers thickness, the rate increases slowly with temperature, with an apparent activation energy of 11.4 ± 2.8 kJ/mol, and shows a first‐order rate in CO pressure and oxygen coverage, similar to bulk Au(110).
203 citations
TL;DR: The Singlet oxygen oxidation of foods was studied in this article, where it was shown that the Singlet oxidization of foods can lead to a significant reduction in the nutritional quality of foods.
Abstract: (1992). Singlet oxygen oxidation of foods. Critical Reviews in Food Science and Nutrition: Vol. 31, No. 3, pp. 211-236.
203 citations
TL;DR: In this paper, the evolution of electronic energy levels of controlled air and oxygen exposed molybdenum trioxide (MoO3) films has been investigated with ultraviolet photoemission spectroscopy, inverse photo-emission spectrum analysis, and x-ray photoEMission spectra.
Abstract: The evolution of electronic energy levels of controlled air and oxygen exposed molybdenum trioxide (MoO3) films has been investigated with ultraviolet photoemission spectroscopy, inverse photoemission spectroscopy, and x-ray photoemission spectroscopy. We found that while most of the electronic levels of as deposited MoO3 films remained largely intact, the reduction in the work function (WF) was substantial. The gradual surface WF change from 6.8 to 5.3 eV was observed for air exposed film, while oxygen exposed film the surface WF saturated at ∼5.7 eV. Two distinct stages of exposure are observed, the first dominated by oxygen adsorption for 1013 L.
202 citations
TL;DR: The results show that there are adaptive changes in root extension involving large-scale reprogramming of gene expression and metabolism when oxygen concentration is decreased in a very narrow range.
202 citations