Charge transfer mechanism in titanium-doped microporous silica for photocatalytic water-splitting applications

Sapp, Wendi; Koodali, Ranjit; Kilin, Dmitri

doi:10.3390/catal6030034

Title: Charge transfer mechanism in titanium-doped microporous silica for photocatalytic water-splitting applications

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Abstract

Solar energy conversion into chemical form is possible using artificial means. One example of a highly-efficient fuel is solar energy used to split water into oxygen and hydrogen. Efficient photocatalytic water-splitting remains an open challenge for researchers across the globe. Despite significant progress, several aspects of the reaction, including the charge transfer mechanism, are not fully clear. Density functional theory combined with density matrix equations of motion were used to identify and characterize the charge transfer mechanism involved in the dissociation of water. A simulated porous silica substrate, using periodic boundary conditions, with Ti⁴⁺ ions embedded on the inner pore wall was found to contain electron and hole trap states that could facilitate a chemical reaction. A trap state was located within the silica substrate that lengthened relaxation time, which may favor a chemical reaction. A chemical reaction would have to occur within the window of photoexcitation; therefore, the existence of a trapping state may encourage a chemical reaction. Furthermore, this provides evidence that the silica substrate plays an integral part in the electron/hole dynamics of the system, leading to the conclusion that both components (photoactive materials and support) of heterogeneous catalytic systems are important in optimization of catalytic efficiency.

Authors:

Sapp, Wendi ^[1]; Koodali, Ranjit ^[1]; Kilin, Dmitri ^[2]

Univ. of South Dakota, Vermillion, SD (United States)
Univ. of South Dakota, Vermillion, SD (United States); North Dakota State Univ., Fargo, ND (United States)

Publication Date:: Mon Feb 29 00:00:00 EST 2016

Research Org.:: Univ. of California, Oakland, CA (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:: 1257976

Grant/Contract Number:: AC02-05CH11231

Resource Type:: Accepted Manuscript

Journal Name:: Catalysts

Additional Journal Information:: Journal Volume: 6; Journal Issue: 3; Journal ID: ISSN 2073-4344

Publisher:: MDPI

Country of Publication:: United States

Language:: English

Subject:: 14 SOLAR ENERGY; water-splitting; heterogeneous catalysis; charge transfer; DFT; non-adiabatic dynamics

Citation Formats


                    Sapp, Wendi, Koodali, Ranjit, and Kilin, Dmitri. Charge transfer mechanism in titanium-doped microporous silica for photocatalytic water-splitting applications.  United States: N. p., 2016. 
Web.  doi:10.3390/catal6030034.

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                    Sapp, Wendi, Koodali, Ranjit, & Kilin, Dmitri. Charge transfer mechanism in titanium-doped microporous silica for photocatalytic water-splitting applications.  United States.  https://doi.org/10.3390/catal6030034

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                    Sapp, Wendi, Koodali, Ranjit, and Kilin, Dmitri. Mon .  
"Charge transfer mechanism in titanium-doped microporous silica for photocatalytic water-splitting applications".  United States.  https://doi.org/10.3390/catal6030034.  https://www.osti.gov/servlets/purl/1257976.

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@article{osti_1257976,

  title        = {Charge transfer mechanism in titanium-doped microporous silica for photocatalytic water-splitting applications},

  author       = {Sapp, Wendi and Koodali, Ranjit and Kilin, Dmitri},

  abstractNote = {Solar energy conversion into chemical form is possible using artificial means. One example of a highly-efficient fuel is solar energy used to split water into oxygen and hydrogen. Efficient photocatalytic water-splitting remains an open challenge for researchers across the globe. Despite significant progress, several aspects of the reaction, including the charge transfer mechanism, are not fully clear. Density functional theory combined with density matrix equations of motion were used to identify and characterize the charge transfer mechanism involved in the dissociation of water. A simulated porous silica substrate, using periodic boundary conditions, with Ti4+ ions embedded on the inner pore wall was found to contain electron and hole trap states that could facilitate a chemical reaction. A trap state was located within the silica substrate that lengthened relaxation time, which may favor a chemical reaction. A chemical reaction would have to occur within the window of photoexcitation; therefore, the existence of a trapping state may encourage a chemical reaction. Furthermore, this provides evidence that the silica substrate plays an integral part in the electron/hole dynamics of the system, leading to the conclusion that both components (photoactive materials and support) of heterogeneous catalytic systems are important in optimization of catalytic efficiency.},

  doi          = {10.3390/catal6030034},

  journal      = {Catalysts},

  number       = 3,

  volume       = 6,

  place        = {United States},

  year         = {Mon Feb 29 00:00:00 EST 2016},

  month        = {Mon Feb 29 00:00:00 EST 2016}

}

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