Carrier dynamics of a visible-light-responsive Ta3N5 photoanode for water oxidation

Ahmed Ziani, Ela Nurlaela, Dattatray Dhawale, Diego Alves Silva, Erkki Alarousu, Omar F. Mohammed, Kazuhiro Takanabe

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Abstract

The physicochemical properties of a tantalum nitride (Ta3N5) photoanode were investigated in detail to understand the fundamental aspects associated with the photoelectrochemical (PEC) water oxidation. The Ta3N5 thin films were synthesized using DC magnetron sputtering followed by annealing in air and nitridation under ammonia (NH3). A polycrystalline structure with a dense morphology of the monoclinic Ta3N5 films was obtained. A relatively low absorption coefficient (104 to 105 cm-1) in the visible light range was measured for Ta3N5, consistent with the nature of the indirect band-gap. Ultra-fast spectroscopic measurements revealed that the Ta3N5 with different thicknesses films possess low transport properties and fast carrier recombination (<10 ps). These critical kinetic properties of Ta3N5 as a photoanode may necessitate high overpotentials to achieve appreciable photocurrents for water oxidation (onset ∼0.6 V vs. RHE).

Original languageEnglish
Pages (from-to)2670-2677
Number of pages8
JournalPhysical Chemistry Chemical Physics
Volume17
Issue number4
DOIs
Publication statusPublished - 28 Jan 2015
Externally publishedYes

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ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Ziani, A., Nurlaela, E., Dhawale, D., Silva, D. A., Alarousu, E., Mohammed, O. F., & Takanabe, K. (2015). Carrier dynamics of a visible-light-responsive Ta3N5 photoanode for water oxidation. Physical Chemistry Chemical Physics, 17(4), 2670-2677. https://doi.org/10.1039/c4cp05616g