Disentangling the Role of Surface Chemical Interactions on Interfacial Charge Transport at BiVO 4 Photoanodes

doi:10.1021/acsami.8b11366

Title: Disentangling the Role of Surface Chemical Interactions on Interfacial Charge Transport at BiVO ₄ Photoanodes

Abstract

Chemical transformations that occur on photoactive materials, such as photoelectrochemical water splitting, are strongly influenced by the surface properties as well as by the surrounding environment. Herein, we elucidate the effects of oxygen and water surface adsorption on band alignment, interfacial charge transfer, and charge-carrier transport by using complementary Kelvin probe measurements and photoconductive atomic force microscopy on bismuth vanadate. By observing variations in surface potential, we show that adsorbed oxygen acts as an electron-trap state at the surface of bismuth vanadate, whereas adsorbed water results in formation of a dipole layer without inducing interfacial charge transfer. The apparent change of trap state density under dry or humid nitrogen, as well as under oxygen-rich atmosphere, proves that surface adsorbates influence charge-carrier transport properties in the material. The finding that oxygen introduces electronically active states on the surface of bismuth vanadate may have important implications for understanding functional characteristics of water splitting photoanodes, devising strategies to passivate interfacial trap states, and elucidating important couplings between energetics and charge transport in reaction environments.

Authors:

Eichhorn, Johanna ^[1];

^[1];

^[2];

^[1]

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Technische Univ. Munchen, Garching (Germany)

Publication Date:: 2018-09-19

Research Org.:: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

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

OSTI Identifier:: 1477400

Grant/Contract Number:: AC02-05CH11231

Resource Type:: Accepted Manuscript

Journal Name:: ACS Applied Materials and Interfaces

Additional Journal Information:: Journal Volume: 10; Journal Issue: 41; Journal ID: ISSN 1944-8244

Publisher:: American Chemical Society (ACS)

Country of Publication:: United States

Language:: English

Subject:: 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats


                    Eichhorn, Johanna, Kastl, Christoph, Schwartzberg, Adam M., Sharp, Ian D., and Toma, Francesca M. Disentangling the Role of Surface Chemical Interactions on Interfacial Charge Transport at BiVO 4 Photoanodes.  United States: N. p., 2018. 
        Web.  doi:10.1021/acsami.8b11366.

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                    Eichhorn, Johanna, Kastl, Christoph, Schwartzberg, Adam M., Sharp, Ian D., & Toma, Francesca M. Disentangling the Role of Surface Chemical Interactions on Interfacial Charge Transport at BiVO 4 Photoanodes.  United States.  doi:10.1021/acsami.8b11366.

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                    Eichhorn, Johanna, Kastl, Christoph, Schwartzberg, Adam M., Sharp, Ian D., and Toma, Francesca M. Wed .  
        "Disentangling the Role of Surface Chemical Interactions on Interfacial Charge Transport at BiVO 4 Photoanodes".  United States.  doi:10.1021/acsami.8b11366.  https://www.osti.gov/servlets/purl/1477400.

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@article{osti_1477400,

  title        = {Disentangling the Role of Surface Chemical Interactions on Interfacial Charge Transport at BiVO 4 Photoanodes},

  author       = {Eichhorn, Johanna and Kastl, Christoph and Schwartzberg, Adam M. and Sharp, Ian D. and Toma, Francesca M.},

  abstractNote = {Chemical transformations that occur on photoactive materials, such as photoelectrochemical water splitting, are strongly influenced by the surface properties as well as by the surrounding environment. Herein, we elucidate the effects of oxygen and water surface adsorption on band alignment, interfacial charge transfer, and charge-carrier transport by using complementary Kelvin probe measurements and photoconductive atomic force microscopy on bismuth vanadate. By observing variations in surface potential, we show that adsorbed oxygen acts as an electron-trap state at the surface of bismuth vanadate, whereas adsorbed water results in formation of a dipole layer without inducing interfacial charge transfer. The apparent change of trap state density under dry or humid nitrogen, as well as under oxygen-rich atmosphere, proves that surface adsorbates influence charge-carrier transport properties in the material. The finding that oxygen introduces electronically active states on the surface of bismuth vanadate may have important implications for understanding functional characteristics of water splitting photoanodes, devising strategies to passivate interfacial trap states, and elucidating important couplings between energetics and charge transport in reaction environments.},

  doi          = {10.1021/acsami.8b11366},

  journal      = {ACS Applied Materials and Interfaces},

  number       = 41,

  volume       = 10,

  place        = {United States},

  year         = {2018},

  month        = {9}

}

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DOI: 10.1021/acsami.8b11366

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Figure 1: Oxygen and water adsorption on BiVO₄ in dark conditions. (a) Time-resolved contact potential difference (CPD) measurements after exposure to humidity. The baseline in dry nitrogen environment is set to zero. Upon increasing the relative humidity to about 40%, the equilibrium ΔCPD is about -27 mV. (b) Schematic bandmore »

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Title: Disentangling the Role of Surface Chemical Interactions on Interfacial Charge Transport at BiVO 4 Photoanodes

Abstract

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Title: Disentangling the Role of Surface Chemical Interactions on Interfacial Charge Transport at BiVO ₄ Photoanodes