Dataset Information

Hierarchical Branched Mesoporous TiO₂-SnO₂ Nanocomposites with Well-Defined n-n Heterojunctions for Highly Efficient Ethanol Sensing.

ABSTRACT: The direct assembly of functional nanoparticles into a highly crystalline mesoporous semiconductor with oriented configurations is challenging but of significance. Herein, an evaporation induced oriented co-assembly strategy is reported to incorporate SnO₂ nanocrystals (NCs) into a 3D branched mesoporous TiO₂ framework by using poly(ethylene oxide)-block-polystyrene (PEO-b-PS) as the template, SnO₂ NCs as the direct tin source, and titanium butoxide (TBOT) as the titania precursor. Owing to the combined properties of ultrasmall particle size (3-5 nm), excellent dispersibility and presence of abundant hydroxyl groups, SnO₂ NCs can easily interact with PEO block of the template through hydrogen bonding and co-assemble with hydrolyzed TBOT to form a novel hierarchical branched mesoporous structure (SHMT). After calcination, the obtained composites exhibit a unique 3D flower-like structure, which consists of numerous mesoporous rutile TiO₂ branches with uniform cylindrical mesopores (≈9 nm). More importantly, the SnO₂ NCs are homogeneously distributed in the mesoporous TiO₂ matrix, forming numerous n-n heterojunctions. Due to the unique textual structures, the SHMT-based gas sensors show excellent gas sensing performance with fast response/recovery dynamics, high sensitivity, and selectivity toward ethanol.

SUBMITTER: Zhao T

PROVIDER: S-EPMC6918105 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Hierarchical Branched Mesoporous TiO2-SnO2 Nanocomposites with Well-Defined n-n Heterojunctions for Highly Efficient Ethanol Sensing.

Zhao Tao T Qiu Pengpeng P Fan Yuchi Y Yang Jianping J Jiang Wan W Wang Lianjun L Deng Yonghui Y Luo Wei W

Advanced science (Weinheim, Baden-Wurttemberg, Germany) 20191024 24

The direct assembly of functional nanoparticles into a highly crystalline mesoporous semiconductor with oriented configurations is challenging but of significance. Herein, an evaporation induced oriented co-assembly strategy is reported to incorporate SnO2 nanocrystals (NCs) into a 3D branched mesoporous TiO2 framework by using poly(ethylene oxide)-block-polystyrene (PEO-b-PS) as the template, SnO2 NCs as the direct tin source, and titanium butoxide (TBOT) ...[more]

PMID: 31871868

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Project description:Perfluorooctanoic acid (PFOA), a typical perfluorinated carboxylic acid, is an emerging type of permanent organic pollutants that are regulated by the Stockholm Convention. The degradation of PFOA, however, is quite challenging largely due to the ultra-high stability of C-F bonds. Compared with other techniques, photocatalytic degradation offers the potential advantages of simple operation under mild conditions as well as exceptional decomposition and defluorination efficiency. Titanium dioxide (TiO2) is one of the most frequently used photocatalysts, but so far, the pristine nanosized TiO2 (e.g., the commercial P25) has been considered inefficient for PFOA degradation, since the photo-generated hydroxyl radicals from TiO2 are not able to directly attack C-F bonds. Mesoporous Sb2O3/TiO2 heterojunctions were therefore rationally designed in this work, of which the confined Sb2O3 nanoparticles in mesoporous TiO2 framework could not only tune the band structure and also increase the number of active sites for PFOA degradation. It was found that, after loading Sb2O3, the absorption of UV light was enhanced, indicating a higher efficiency of light utilization; while the band gap was reduced, which accelerated the separation of photo-generated charge carriers; and most importantly, the valence band edge of the Sb2O3/TiO2 heterojunction was significantly lifted so as to prevent the occurrence of hydroxyl radical pathway. Under the optimal ratio of Sb2O3-TiO2, the resulting catalysts managed to remove 81.7% PFOA in 2 h, with a degradation kinetics 4.2 times faster than the commercial P25. Scavenger tests and electron spin resonance spectra further revealed that such improvement was mainly attributed to the formation of superoxide radicals and photo-generated holes, in which the former drove the decarboxylation from C7F15COOH-C7F15 •, and the latter promoted the direct electron transfer for the conversion of C7F15COO--C7F15COO•. The Sb2O3/TiO2 photocatalysts were highly recyclable, with nearly 90% of the initial activity being retained after five consecutive cycles, guaranteeing the feasibility of long-term operation.

Dataset Information

Hierarchical Branched Mesoporous TiO₂-SnO₂ Nanocomposites with Well-Defined n-n Heterojunctions for Highly Efficient Ethanol Sensing.

Publications

Hierarchical Branched Mesoporous TiO<sub>2</sub>-SnO<sub>2</sub> Nanocomposites with Well-Defined n-n Heterojunctions for Highly Efficient Ethanol Sensing.

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