Presentation Title

Deposition of Thin Films on the Inside Surfaces of Mesoporous Materials by Atomic Layer Deposition

Faculty Mentor

Francisco Zaera

Start Date

18-11-2017 12:30 PM

End Date

18-11-2017 1:30 PM

Location

BSC-Ursa Minor 120

Session

Poster 2

Type of Presentation

Poster

Subject Area

engineering_computer_science

Abstract

The deposition of thin films inside mesoporous materials allows for materials to be transformed into active catalysts. In this experiment, titanium dioxide (TiO2) was grown and deposited into the ordered mesoporous silica (OMS) SBA-15 through atomic layer deposition in order to work as a binding agent for future deposition of nanoparticles. SBA-15 (Santa Barbara Amorphous), a nontoxic, white pigmented powder was the OMS of interest due to its large surface area, tunable pore size (7-10 nm), and thermal stability. Although the growth of TiO2 on surfaces using specific precursors is a widely known method, deposition inside mesoporous materials introduces several new complications not properly addressed to date; the most notable being limited diffusivity; rapid excess exposures, for instance, can cause the pores to be plugged, disrupting uniform film growth. In order to assure evenly distributed layers of TiO2 throughout, the process of ALD was carried out using two alternating reactants ([tetrakis (dimethylamido) titanium (IV)]-TDMAT-, which was vaporized at 40°C, and deionized water) and a purge-gas (N2). Each ALD cycle consisted of a TDMAT exposure of 20 minutes at 1 mTorr, followed by a purge with N2 gas for 50 minutes at 1000 mTorr, exposure to deionized water for 10 minutes at 8 mTorr, and finally, a second purge for another 50 minutes. Several samples with increasing TiO2 film thicknesses were prepared by using various number of ALD cycles, and characterized by acquiring appropriate BET adsorption isotherms. It was found that the pore dimensions do decrease uniformly with increasing number of ALD cycles, assuring uniform growth of TiO2 inside of the SBA-15. Future work consisting of deposition of Au nanoparticles inside the TiO2 /SBA-15 samples will allow for the manufacturing of the targeted catalyst.

Summary of research results to be presented

BET analysis was used in order to differentiate the amount of TiO2 present as each cycle was carried out. Graphical representations were obtained, in which average pore diameter,adsorption, and desorption differences varied, and thus, set an idealized exposure interval in order to grow TiO2 uniformly inside of the SBA-15.

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Nov 18th, 12:30 PM Nov 18th, 1:30 PM

Deposition of Thin Films on the Inside Surfaces of Mesoporous Materials by Atomic Layer Deposition

BSC-Ursa Minor 120

The deposition of thin films inside mesoporous materials allows for materials to be transformed into active catalysts. In this experiment, titanium dioxide (TiO2) was grown and deposited into the ordered mesoporous silica (OMS) SBA-15 through atomic layer deposition in order to work as a binding agent for future deposition of nanoparticles. SBA-15 (Santa Barbara Amorphous), a nontoxic, white pigmented powder was the OMS of interest due to its large surface area, tunable pore size (7-10 nm), and thermal stability. Although the growth of TiO2 on surfaces using specific precursors is a widely known method, deposition inside mesoporous materials introduces several new complications not properly addressed to date; the most notable being limited diffusivity; rapid excess exposures, for instance, can cause the pores to be plugged, disrupting uniform film growth. In order to assure evenly distributed layers of TiO2 throughout, the process of ALD was carried out using two alternating reactants ([tetrakis (dimethylamido) titanium (IV)]-TDMAT-, which was vaporized at 40°C, and deionized water) and a purge-gas (N2). Each ALD cycle consisted of a TDMAT exposure of 20 minutes at 1 mTorr, followed by a purge with N2 gas for 50 minutes at 1000 mTorr, exposure to deionized water for 10 minutes at 8 mTorr, and finally, a second purge for another 50 minutes. Several samples with increasing TiO2 film thicknesses were prepared by using various number of ALD cycles, and characterized by acquiring appropriate BET adsorption isotherms. It was found that the pore dimensions do decrease uniformly with increasing number of ALD cycles, assuring uniform growth of TiO2 inside of the SBA-15. Future work consisting of deposition of Au nanoparticles inside the TiO2 /SBA-15 samples will allow for the manufacturing of the targeted catalyst.