The role of the domain size and titanium dopant in nanocrystalline hematite thin films for water photolysis

doi:https://doi.org/10.1039/C5NR05894E

Title: The role of the domain size and titanium dopant in nanocrystalline hematite thin films for water photolysis

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Abstract

Here we develop a novel technique for preparing high quality Ti-doped hematite thin films for photoelectrochemical (PEC) water splitting, through sputtering deposition of metallic iron films from an iron target embedded with titanium (dopants) pellets, followed by a thermal oxidation step that turns the metal films into doped hematite. It is found that the hematite domain size can be tuned from ~10 nm to over 100 nm by adjusting the sputtering atmosphere from more oxidative to mostly inert. The better crystallinity at a larger domain size ensures excellent PEC water splitting performance, leading to record high photocurrent from pure planar hematite thin films on FTO substrates. Titanium doping further enhances the PEC performance of hematite photoanodes. The photocurrent is improved by 50%, with a titanium dopant concentration as low as 0.5 atom%. As a result, it is also found that the role of the titanium dopant in improving the PEC performance is not apparently related to the films’ electrical conductivity which had been widely believed, but is more likely due to the passivation of surface defects by the titanium dopants.

Authors:

Yan, Danhua ^[1]; Tao, Jing ^[2]; Kisslinger, Kim ^[2]; Cen, Jiajie ^[3]; Wu, Qiyuan ^[3]; Orlov, Alexander ^[3]; Liu, Mingzhao ^[2]

Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States)
Brookhaven National Lab. (BNL), Upton, NY (United States)
Stony Brook Univ., Stony Brook, NY (United States)

Publication Date:: 2015-10-13

Research Org.:: Brookhaven National Lab. (BNL), Upton, NY (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)

OSTI Identifier:: 1224784

Alternate Identifier(s):: OSTI ID: 1237187

Report Number(s):: BNL-108520-2015-JA; BNL-111762-2016-JA
Journal ID: ISSN 2040-3364; NANOHL; R&D Project: 16064; KC0403020

Grant/Contract Number:: SC00112704

Resource Type:: Journal Article: Accepted Manuscript

Journal Name:: Nanoscale

Additional Journal Information:: Journal Name: Nanoscale; Journal ID: ISSN 2040-3364

Publisher:: Royal Society of Chemistry

Country of Publication:: United States

Language:: English

Subject:: 77 NANOSCIENCE AND NANOTECHNOLOGY; photoelectrochemical water splitting; strontium titanate; indirect band gap semiconductor; graded doping; Center for Functional Nanomaterials

Citation Formats


                    Yan, Danhua, Tao, Jing, Kisslinger, Kim, Cen, Jiajie, Wu, Qiyuan, Orlov, Alexander, and Liu, Mingzhao. The role of the domain size and titanium dopant in nanocrystalline hematite thin films for water photolysis.  United States: N. p., 2015. 
        Web.  doi:10.1039/C5NR05894E.

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                    Yan, Danhua, Tao, Jing, Kisslinger, Kim, Cen, Jiajie, Wu, Qiyuan, Orlov, Alexander, & Liu, Mingzhao. The role of the domain size and titanium dopant in nanocrystalline hematite thin films for water photolysis.  United States.  https://doi.org/10.1039/C5NR05894E

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                    Yan, Danhua, Tao, Jing, Kisslinger, Kim, Cen, Jiajie, Wu, Qiyuan, Orlov, Alexander, and Liu, Mingzhao. Tue .  
        "The role of the domain size and titanium dopant in nanocrystalline hematite thin films for water photolysis".  United States.  https://doi.org/10.1039/C5NR05894E.  https://www.osti.gov/servlets/purl/1224784.

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@article{osti_1224784,

  title        = {The role of the domain size and titanium dopant in nanocrystalline hematite thin films for water photolysis},

  author       = {Yan, Danhua and Tao, Jing and Kisslinger, Kim and Cen, Jiajie and Wu, Qiyuan and Orlov, Alexander and Liu, Mingzhao},

  abstractNote = {Here we develop a novel technique for preparing high quality Ti-doped hematite thin films for photoelectrochemical (PEC) water splitting, through sputtering deposition of metallic iron films from an iron target embedded with titanium (dopants) pellets, followed by a thermal oxidation step that turns the metal films into doped hematite. It is found that the hematite domain size can be tuned from ~10 nm to over 100 nm by adjusting the sputtering atmosphere from more oxidative to mostly inert. The better crystallinity at a larger domain size ensures excellent PEC water splitting performance, leading to record high photocurrent from pure planar hematite thin films on FTO substrates. Titanium doping further enhances the PEC performance of hematite photoanodes. The photocurrent is improved by 50%, with a titanium dopant concentration as low as 0.5 atom%. As a result, it is also found that the role of the titanium dopant in improving the PEC performance is not apparently related to the films’ electrical conductivity which had been widely believed, but is more likely due to the passivation of surface defects by the titanium dopants.},

  doi          = {10.1039/C5NR05894E},

  url          = {https://www.osti.gov/biblio/1224784},
  journal      = {Nanoscale},

  issn         = {2040-3364},

  number       = ,

  volume       = ,

  place        = {United States},

  year         = {2015},

  month        = {10}

}

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