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Matter F, Niederberger M. Optimization of Mass and Light Transport in Nanoparticle-Based Titania Aerogels. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2023; 35:7995-8008. [PMID: 37840780 PMCID: PMC10568969 DOI: 10.1021/acs.chemmater.3c01218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 08/31/2023] [Indexed: 10/17/2023]
Abstract
Aerogels composed of preformed titania nanocrystals exhibit a large surface area, open porosity, and high crystallinity, making these materials appealing for applications in gas-phase photocatalysis. Recent studies on nanoparticle-based titania aerogels have mainly focused on optimizing their composition to improve photocatalytic performance. Little attention has been paid to modification at the microstructural level to control fundamental properties such as gas permeability and light transmittance, although these features are of fundamental importance, especially for photocatalysts of macroscopic size. In this study, we systematically control the porosity and transparency of titania gels and aerogels by adjusting the particle loading and nonsolvent fraction during the gelation step. Mass transport and light transport were assessed by gas permeability and light attenuation measurements, and the results were related to the microstructure determined by gas sorption analysis and scanning electron microscopy. Mass transport through the aerogel network was found to proceed primarily via Knudsen diffusion leading to relatively low permeabilities in the range of 10-5-10-6 m2/s, despite very high porosities of 96-99%. While permeability was found to depend mainly on particle loading, the optical properties are predominantly affected by the amount of nonsolvent during gelation, allowing independent tuning of mass and light transport.
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Affiliation(s)
- Fabian Matter
- Laboratory for Multifunctional
Materials, Department of Materials, ETH
Zurich, Vladimir-Prelog-Weg 5, 8093 Zurich, Switzerland
| | - Markus Niederberger
- Laboratory for Multifunctional
Materials, Department of Materials, ETH
Zurich, Vladimir-Prelog-Weg 5, 8093 Zurich, Switzerland
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2
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Matter F, Niederberger M. The Importance of the Macroscopic Geometry in Gas-Phase Photocatalysis. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2105363. [PMID: 35243811 PMCID: PMC9069382 DOI: 10.1002/advs.202105363] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Indexed: 05/04/2023]
Abstract
Photocatalysis has the potential to make a major technological contribution to solving pressing environmental and energy problems. There are many strategies for improving photocatalysts, such as tuning the composition to optimize visible light absorption, charge separation, and surface chemistry, ensuring high crystallinity, and controlling particle size and shape to increase overall surface area and exploit the reactivity of individual crystal facets. These processes mainly affect the nanoscale and are therefore summarized as nanostructuring. In comparison, microstructuring is performed on a larger size scale and is mainly concerned with particle assembly and thin film preparation. Interestingly, most structuring efforts stop at this point, and there are very few examples of geometry optimization on a millimeter or even centimeter scale. However, the recent work on nanoparticle-based aerogel monoliths has shown that this size range also offers great potential for improving the photocatalytic performance of materials, especially when the macroscopic geometry of the monolith is matched to the design of the photoreactor. This review article is dedicated to this aspect and addresses some issues and open questions that arise when working with macroscopically large photocatalysts. Guidelines are provided that could help develop novel and efficient photocatalysts with a truly 3D architecture.
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Affiliation(s)
- Fabian Matter
- Laboratory for Multifunctional MaterialsDepartment of MaterialsETH ZurichVladimir‐Prelog‐Weg 5Zurich8093Switzerland
| | - Markus Niederberger
- Laboratory for Multifunctional MaterialsDepartment of MaterialsETH ZurichVladimir‐Prelog‐Weg 5Zurich8093Switzerland
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3
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Niu Y, Li F, Zhao W, Cheng W. Fabrication and application of macroscopic nanowire aerogels. NANOSCALE 2021; 13:7430-7446. [PMID: 33928971 DOI: 10.1039/d0nr09236c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Assembly of nanowires into three-dimensional macroscopic aerogels not only bridges a gap between nanowires and macroscopic bulk materials but also combines the benefits of two worlds: unique structural features of aerogels and unique physical and chemical properties of nanowires, which has triggered significant progress in the design and fabrication of nanowire-based aerogels for a diverse range of practical applications. This article reviews the methods developed for processing nanowires into three-dimensional monolithic aerogels and the applications of the resultant nanowire aerogels in many emerging fields. Detailed discussions are given on gelation mechanisms involved in every preparation method and the pros and cons of the different methods. Furthermore, we systematically scrutinize the application of nanowire-based aerogels in the fields of thermal management, energy storage and conversion, catalysis, adsorbents, sensors, and solar steam generation. The unique benefits offered by nanowire-based aerogels in every application field are clarified. We also discuss how to improve the performance of nanowire-based aerogels in those fields by engineering the compositions and structures of the aerogels. Finally, we provide our perspectives on future development of nanowire-based aerogels.
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Affiliation(s)
- Yutong Niu
- College of Materials, Xiamen University, 422 Siming South Road, Xiamen, Fujian 361005, China.
| | - Fuzhong Li
- College of Materials, Xiamen University, 422 Siming South Road, Xiamen, Fujian 361005, China.
| | - Wuxi Zhao
- College of Materials, Xiamen University, 422 Siming South Road, Xiamen, Fujian 361005, China.
| | - Wei Cheng
- College of Materials, Xiamen University, 422 Siming South Road, Xiamen, Fujian 361005, China. and Fujian Key Laboratory of Materials Genome, Xiamen University, China
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Alekseev ES, Alentiev AY, Belova AS, Bogdan VI, Bogdan TV, Bystrova AV, Gafarova ER, Golubeva EN, Grebenik EA, Gromov OI, Davankov VA, Zlotin SG, Kiselev MG, Koklin AE, Kononevich YN, Lazhko AE, Lunin VV, Lyubimov SE, Martyanov ON, Mishanin II, Muzafarov AM, Nesterov NS, Nikolaev AY, Oparin RD, Parenago OO, Parenago OP, Pokusaeva YA, Ronova IA, Solovieva AB, Temnikov MN, Timashev PS, Turova OV, Filatova EV, Philippov AA, Chibiryaev AM, Shalygin AS. Supercritical fluids in chemistry. RUSSIAN CHEMICAL REVIEWS 2020. [DOI: 10.1070/rcr4932] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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5
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Natsathaporn P, Jenjob R, Pattanasattayavong P, Yiamsawas D, Crespy D. Photocatalytic degradation of pesticides by nanofibrous membranes fabricated by colloid-electrospinning. NANOTECHNOLOGY 2020; 31:215603. [PMID: 31995794 DOI: 10.1088/1361-6528/ab713d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Photocatalytic degradation of organic pollutants is a promising way to clean wastewater. Herein, we develop and compare two processes for fabricating nanofibrous membranes with photocatalytic properties. Hybrid nanofibers are produced by colloid-electrospinning and composed of metal oxide nanoparticles on sintered SiO2 nanoparticles. The latter serves as support for the photocatalyst and preserves the structural integrity of nanofibers. Adsorption of metal salts on crosslinked polymer/SiO2 fibers followed by calcination allows for the obtention of fibers with large amounts of metal oxide. Nanofibrous membranes with supported ZnO, In2O3, or mixture of both, display photocatalytic activity upon UV irradiation. The membranes can degrade a dye and an organophosphate pesticide more effectively than membranes directly fabricated from the calcination of metal oxides.
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Affiliation(s)
- Papada Natsathaporn
- Department of Materials Science and Engineering, School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong 21210, Thailand
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Hierarchical microfibrillar gels from evaporation-induced anisotropic self-assembly of in situ-generated nanocrystals. J Colloid Interface Sci 2020; 558:78-84. [PMID: 31585224 DOI: 10.1016/j.jcis.2019.09.110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Revised: 09/26/2019] [Accepted: 09/27/2019] [Indexed: 12/17/2022]
Abstract
Whilst nanocrystal gels may be formed via destabilization of pre-functionalized nanocrystal dispersions, gelation via assembly of unfunctionalized nanocrystals into fibrillar networks remains a significant challenge. Here, we show that gels with hierarchical microfibrillar networks are formed from anisotropic self-assembly of in situ-generated mesolamellar nanocrystals upon evaporation of ZnO nanofluids. The obtained gels display the thermo-reversible behavior characteristic of a non-covalent physical gel. We elucidate a three-stage gelation mechanism. In the pre-nucleation stage, the cloudy ZnO nanofluid transforms into a transparent stable suspension, comprising multi-branched networks of aggregates self-assembled from in situ-generated layered zinc hydroxide (LZH) nanocrystals upon solvent evaporation. In the subsequent nucleation and anisotropic 1D fibre growth stage, further evaporation triggers nucleation and growth of 1D nanofibers through reorganization of the nanocrystal aggregates, before rapid nanofibre bundling leading to microfibrillar networks in the ultimate gelation stage. Our results provide mechanistic insights for hierarchical self-assembly of nanocrystals into fibrillar gels and open up facile fabrication routes using reactive transition metal-oxide nanofluids for new functional fibres and gels.
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Xu Y, Guo Q, Huang L, Feng H, Zhang C, Xu H, Wang M. Toward Efficient Preconcentrating Photocatalysis: 3D g-C 3N 4 Monolith with Isotype Heterojunctions Assembled from Hybrid 1D and 2D Nanoblocks. ACS APPLIED MATERIALS & INTERFACES 2019; 11:31934-31942. [PMID: 31402642 DOI: 10.1021/acsami.9b09290] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The macroscopic integration of the microscopic catalyst is one of the most promising strategies for photocatalytic technology in facing practical applications. However, in addition to the unsatisfactory photoactivated exciton separation, a new problem restricting the catalytic efficiency is the unmatched kinetics between the reactant diffusion and the photochemical reaction. Here, we report an isotype heterojunctional three-dimensional g-C3N4 monolith which is assembled from the hybrid building blocks of the nanowires and nanosheets. Benefiting from its hierarchically porous network and abundant heterojunctions, this catalytic system exhibits inherently promoted efficiency in light absorption and exciton separation, thus leading to a desirably improved photocatalytic performance. Furthermore, thanks to the structural and functional advantages of the constructed g-C3N4 monolith, a novel strategy of preconcentrating photocatalysis featuring the successive filtration, adsorption, and photocatalysis has been further developed, which could technically coordinate the kinetic differences and result in over-ten-time enhancement on the efficiency compared with the traditional photocatalytic system. Beyond providing new insights into the structural design and innovative application of the monolithic photocatalyst, this work may further open up novel technological revolutions in sewage treatment, air purification, microbial control, etc.
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Affiliation(s)
- Yingfeng Xu
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling , Hangzhou 310013 , P. R. China
| | - Qiaoqi Guo
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling , Hangzhou 310013 , P. R. China
| | - Le Huang
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling , Hangzhou 310013 , P. R. China
| | - Huajun Feng
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling , Hangzhou 310013 , P. R. China
| | - Chen Zhang
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai , 200050 , P. R. China
| | | | - Meizhen Wang
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling , Hangzhou 310013 , P. R. China
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8
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Gelation of plasmonic metal oxide nanocrystals by polymer-induced depletion attractions. Proc Natl Acad Sci U S A 2018; 115:8925-8930. [PMID: 30127030 DOI: 10.1073/pnas.1806927115] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Gelation of colloidal nanocrystals emerged as a strategy to preserve inherent nanoscale properties in multiscale architectures. However, available gelation methods to directly form self-supported nanocrystal networks struggle to reliably control nanoscale optical phenomena such as photoluminescence and localized surface plasmon resonance (LSPR) across nanocrystal systems due to processing variabilities. Here, we report on an alternative gelation method based on physical internanocrystal interactions: short-range depletion attractions balanced by long-range electrostatic repulsions. The latter are established by removing the native organic ligands that passivate tin-doped indium oxide (ITO) nanocrystals while the former are introduced by mixing with small PEG chains. As we incorporate increasing concentrations of PEG, we observe a reentrant phase behavior featuring two favorable gelation windows; the first arises from bridging effects while the second is attributed to depletion attractions according to phase behavior predicted by our unified theoretical model. Our assembled nanocrystals remain discrete within the gel network, based on X-ray scattering and high-resolution transmission electron microscopy. The infrared optical response of the gels is reflective of both the nanocrystal building blocks and the network architecture, being characteristic of ITO nanocrystals' LSPR with coupling interactions between neighboring nanocrystals.
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Yang Y, Zhang Q, Zhang R, Ran T, Wan W, Zhou Y. Compressible and Recyclable Monolithic g-C 3N 4/Melamine Sponge: A Facile Ultrasonic-Coating Approach and Enhanced Visible-Light Photocatalytic Activity. Front Chem 2018; 6:156. [PMID: 29868559 PMCID: PMC5968098 DOI: 10.3389/fchem.2018.00156] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 04/19/2018] [Indexed: 12/03/2022] Open
Abstract
Powdery photocatalysts seriously restrict their practical application due to the difficult recycle and low photocatalytic activity. In this work, a monolithic g-C3N4/melamine sponge (g-C3N4/MS) was successfully fabricated by a cost-effective ultrasonic-coating route, which is easy to achieve the uniform dispersion and firm loading of g-C3N4 on MS skeleton. The monolithic g-C3N4/MS entirely inherits the porous structure of MS and results in a larger specific surface area (SSA) than its powdery counterpart. Benefit from this monolithic structure, g-C3N4/MS gains more exposed active sites, enhanced visible-light absorption and separation of photogenerated carriers, thus achieving noticeable photocatalytic activity on nitric oxide (NO) removal and CO2 reduction. Specifically, NO removal ratio is as high as 78.6% which is 4.5 times higher than that of the powdery g-C3N4, and yield rate of CO and CH4 attains 7.48 and 3.93 μmol g−1 h−1. Importantly, the features of low-density, high porosity, good elasticity, and firmness, not only endow g-C3N4/MS with flexibility in various environmental applications, but also make it easy to recycle and stable for long-time application. Our work provides a feasible approach to fabricate novel monolithic photocatalysts with large-scale production and application.
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Affiliation(s)
- Ye Yang
- The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Chengdu, China.,State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, China
| | - Qian Zhang
- The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Chengdu, China
| | - Ruiyang Zhang
- The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Chengdu, China
| | - Tao Ran
- The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Chengdu, China
| | - Wenchao Wan
- The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Chengdu, China
| | - Ying Zhou
- The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Chengdu, China.,State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, China
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10
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Rechberger F, Niederberger M. Synthesis of aerogels: from molecular routes to 3-dimensional nanoparticle assembly. NANOSCALE HORIZONS 2017; 2:6-30. [PMID: 32260673 DOI: 10.1039/c6nh00077k] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Colloidal nanocrystals are extensively used as building blocks in nanoscience, and amazing results have been achieved in assembling them into ordered, close-packed structures. But in spite of great efforts, the size of these structures is typically restricted to a few micrometers, and it is very hard to extend them into the macroscopic world. In comparison, aerogels are macroscopic materials, highly porous, disordered, ultralight and with immense surface areas. With these distinctive characteristics, they are entirely contrary to common nanoparticle assemblies such as superlattices or nanocrystal solids, and therefore cover a different range of applications. While aerogels are traditionally synthesized by molecular routes based on aqueous sol-gel chemistry, in the last few years the gelation of nanoparticle dispersions became a viable alternative to improve the crystallinity and to widen the structural, morphological and compositional complexity of aerogels. In this Review, the different approaches to inorganic non-siliceous and non-carbon aerogels are addressed. We start our discussion with wet chemical routes involving molecular precursors, followed by processing methods using nanoparticles as building blocks. A unique feature of many of these routes is the fact that a macroscopic, often monolithic body is produced by pure self-assembly of nanosized colloids without the need for any templates.
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Affiliation(s)
- Felix Rechberger
- Laboratory for Multifunctional Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, CH-8093 Zurich, Switzerland.
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11
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Li Y, Zhang Q, Li X, Bai H, Li W, Zeng T, Xi G. Ligand-free and size-controlled synthesis of oxygen vacancy-rich WO3−x quantum dots for efficient room-temperature formaldehyde gas sensing. RSC Adv 2016. [DOI: 10.1039/c6ra20531c] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The present work provides an effective synthetic route for oxygen vacancy-rich WO3−x QDs. More importantly, the WO3−x QDs displayed high formaldehyde sensitivity with a detection limit of 1.5 ppm at room temperature.
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Affiliation(s)
- Yahui Li
- Nanomaterials and Nanoproducts Research Center
- Chinese Academy of Inspection and Quarantine
- Beijing
- China
| | - Qiqi Zhang
- Nanomaterials and Nanoproducts Research Center
- Chinese Academy of Inspection and Quarantine
- Beijing
- China
| | - Xinshi Li
- Nanomaterials and Nanoproducts Research Center
- Chinese Academy of Inspection and Quarantine
- Beijing
- China
| | - Hua Bai
- Nanomaterials and Nanoproducts Research Center
- Chinese Academy of Inspection and Quarantine
- Beijing
- China
| | - Wentao Li
- Nanomaterials and Nanoproducts Research Center
- Chinese Academy of Inspection and Quarantine
- Beijing
- China
| | - Tingting Zeng
- Nanomaterials and Nanoproducts Research Center
- Chinese Academy of Inspection and Quarantine
- Beijing
- China
| | - Guangcheng Xi
- Nanomaterials and Nanoproducts Research Center
- Chinese Academy of Inspection and Quarantine
- Beijing
- China
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