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Tunable sol-gel synthesis of TiO2 aerogels with adjustable surface area and open porosity applied in photocatalytic reactions

Rose, Alexandra and Hofmann, Anja and Voepel, Pascal and Marschall, Roland and Milow, Barbara (2022) Tunable sol-gel synthesis of TiO2 aerogels with adjustable surface area and open porosity applied in photocatalytic reactions. Seventh International Conference on Multifunctional, Hybrid and Nanomaterials, 2022-10-19 - 2022-10-22, Genua, Italien.

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TiO2 aerogels are nanostructured materials which offer many advantages regarding the microstructural and semiconducting properties favored for photocatalytic applications. Active reaction sites on the high surface area of TiO2 aerogels are much better accessible through the high porosity of the material. This characteristic favors the adsorption and diffusion of reactants. Besides, the interconnected network of the aerogels, which offers long diffusion pathways for photogenerated electrons, the structural defects e.g. surface defects provide charge carrier traps for electrons leading to an improved charge separation and charge carrier storage capability. A novel acid-catalyzed sol-gel synthesis route for mesoporous TiO2 aerogels is presented. High surface areas and pore volumes can be obtained for the as-synthesized TiO2 aerogels based on alkoxide precursor hydrolysis and condensation with subsequent supercritical drying. X-ray diffraction and TEM analysis reveal the semi-crystalline character of the as-synthesized TiO2 aerogel besides the typical mesoporous structure and high surface area with narrow pore size distribution. Varying calcination temperatures of the TiO2 aerogels lead to a decrease of porosity and surface area but an increase of crystallinity. Photocatalytic experiments show the ability of the aerogels to store photogenerated electrons over several hours. This can be related to the high surface area and presumably high amount of surface defects. XPS results of the as-synthesized aerogel reveal the presence of Ti3+ states which is associated with surface defects e.g oxygen vacancies serving as electron traps. The effect of electron storage decreases with temperature treatments of the as-synthesized TiO2 aerogel, whereas the hydrogen evolution rate increases. This can be traced back to an improved interconnection of the TiO2 nanocrystals and therefore improved charge separation. The presented TiO2 aerogel is a potential candidate also for other photocatalytic reactions e.g. nitrogen reduction to ammonia (A. Rose et al, ChemRxiv, DOI: 10.26434/chemrxiv-2021-vxkpq-v2, 2022).

Item URL in elib:https://elib.dlr.de/190496/
Document Type:Conference or Workshop Item (Poster)
Title:Tunable sol-gel synthesis of TiO2 aerogels with adjustable surface area and open porosity applied in photocatalytic reactions
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Voepel, PascalUNSPECIFIEDhttps://orcid.org/0000-0001-8233-7261UNSPECIFIED
Marschall, RolandUNSPECIFIEDhttps://orcid.org/0000-0002-1057-0459UNSPECIFIED
Milow, BarbaraUNSPECIFIEDhttps://orcid.org/0000-0002-6350-7728UNSPECIFIED
Date:19 October 2022
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Keywords:TiO2 aerogel, electron storage, photocatalysis, hydrogen production, nitrogen reduction
Event Title:Seventh International Conference on Multifunctional, Hybrid and Nanomaterials
Event Location:Genua, Italien
Event Type:international Conference
Event Start Date:19 October 2022
Event End Date:22 October 2022
HGF - Research field:Energy
HGF - Program:Materials and Technologies for the Energy Transition
HGF - Program Themes:Chemical Energy Carriers
DLR - Research area:Energy
DLR - Program:E VS - Combustion Systems
DLR - Research theme (Project):E - Materials for Chemical Energy Carriers
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Aerogels and Aerogel Composites
Deposited By: Rose, Alexandra
Deposited On:29 Nov 2022 08:41
Last Modified:24 Apr 2024 20:51

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