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BET theory

About: BET theory is a research topic. Over the lifetime, 9046 publications have been published within this topic receiving 286142 citations.


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TL;DR: In this paper, a series of Fe2O3-CeO2 composite catalysts were synthesized by coprecipitation and characterized by X-ray diffraction (XRD), Raman spectroscopy, and X-Ray photoelectron spectrography (XPS).
Abstract: A series of Fe2O3–CeO2 composite catalysts were synthesized by coprecipitation and characterized by X-ray diffraction (XRD), BET surface area measurement, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Their catalytic activities in CO oxidation were also tested. The Fe2O3–CeO2 composites with an Fe molar percentage below 0.3 form solid solutions with the CeO2 cubic fluorite structure, in which the doped Fe3+ initially substitutes Ce4+ in fluorite cubic CeO2, but then mostly locate in the interstitial sites after a critical concentration of doped Fe3+. With an Fe molar percentage between 0.3 and 0.95, the Fe2O3–CeO2 composites are mixed oxides of the cubic fluorite CeO2 solid solution and the hematite Fe2O3. XPS results indicate that CeO2 is enriched in the surface region of Fe2O3–CeO2 composites. The Fe2O3–CeO2 composites have much higher catalytic activities in CO oxidation than the individual pure CeO2 and Fe2O3, and the Fe0.1Ce0.9 composite shows the best catalytic performance. The structure-activity relation of the Fe2O3–CeO2 composites in CO oxidation is discussed in terms of the formation of solid solution and surface oxygen vacancies. Our results demonstrate a proportional relation between the catalytic activity of cubic CeO2-like solid solutions and their density of oxygen vacancies, which directly proves the formation of oxygen vacancies as the key step in CO oxidation over oxide catalysts.

189 citations

Journal ArticleDOI
TL;DR: In this article, 3D flower-and 2D branching sheet-like CuO nanostructures have been synthesized by a microwave-assisted hydrothermal method, and the phase and morphology observations showed the formation of monoclinic CuO structures with well-defined morphology.
Abstract: 3D flower- and 2D branching sheet-like CuO nanostructures have been synthesized by a microwave-assisted hydrothermal method. The samples were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (IR), UV–vis diffuse reflectance spectroscopy (UV-DRS), and Brunauer–Emmett–Teller (BET) specific surface area analysis. The phase and morphology observations showed the formation of monoclinic CuO nanostructures with well-defined morphology. BET analysis displayed that the measured surface area was 15.0 m 2 g −1 for CuO flowers, and 20.8 m 2 g −1 for CuO nanosheets. Gas sensing properties of the as-synthesized CuO nanostructures were evaluated by the detection of volatile and toxic gases including ethanol, ethyl-acetate, acetone, xylene, and toluene. It was found that CuO flowers exhibited an enhanced gas response to the five gases at 260 °C, compared to CuO nanosheets. Furthermore, at 1000 ppm, the CuO flower sensor gave a higher response to ethyl-acetate ( R g / R a = 4.6) and ethanol ( R g / R a = 4.0), in comparison with toluene ( R g / R a = 2.8). In addition, the CuO flowers displayed a rapid response and recovery as well as good reproducibility.

188 citations

Journal ArticleDOI
TL;DR: Experimental results indicated the potential use of rice bran as a precursor in the activated carbon preparation process, thus representing an economically promising material.

188 citations

Journal ArticleDOI
TL;DR: In this article, mesoporous In 2 O 3 nanofibers with a high surface area were synthesized by calcining electrospun polyvinyl alcohol (PVA)/indium acetate composite fibers.
Abstract: Mesoporous In 2 O 3 nanofibers with a high surface area were synthesized by calcining electrospun polyvinyl alcohol (PVA)/indium acetate composite fibers. A PVA solution and indium acetate were mixed and electrospun. After calcining the PVA/indium acetate composite nanofiber precursor, mesoporous In 2 O 3 nanofibers were successfully formed. These nanofibers had diameters in the range of 150–200 nm and consisted of cubic indium oxide nanocrystals with a primary particle size of 10–20 nm. The Brunauer–Emmett–Teller (BET) surface area of the In 2 O 3 nanofibers was strongly affected by the calcining temperature. The BET surface area of the fibers calcined at 400 °C was significantly higher than the surface area of the nanofibers calcined at 500 °C or 600 °C and of the commercial In 2 O 3 powder. The response of mesoporous In 2 O 3 nanofibers to CO in air is strongly affected by the surface area. The highly elevated response of In 2 O 3 nanofibers calcined at 400 °C could be attributed to the high surface area, which provides a large amount of surface sites for adsorption and reaction of CO. The results demonstrate that the electrospinning approach is an easy and useful method to synthesize metal oxides with mesopores and high surface area, which may enhance their gas sensing properties.

188 citations

Journal ArticleDOI
TL;DR: In this article, the photocatalytic activity of LaFeO3 was investigated for hydrogen generation through sacrificial donor assisted water splitting reaction by varying conditions in feasible parametric changes using visible light source, ethanol as a sacrificial donors and Pt solution of H2PtCl6 as a co-catalyst.

187 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023166
2022356
2021525
2020551
2019533
2018531