Dual modification of hematite photoanode by Sn-doping and Nb2O5 layer for water oxidation

Tae Hwa Jeon, Alok D. Bokare, Dong Suk Han, Ahmed Abdel-Wahab, Hyunwoong Park, Wonyong Choi

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Porous hematite (α-Fe2O3) films doped with Sn(IV) and coated with an ultrathin (∼2 nm thick) Nb2O5 passivation layer were synthesized, and the photoelectrochemical (PEC) water oxidation performance and durability of the hematite were examined in detail. As compared to hematite samples modified by either doping or passivation, dual-modified hematite exhibited a promising PEC water oxidation performance under AM 1.5 irradiation. A stable photocurrent was maintained under prolonged irradiation over 24 h, while O2 was produced from water with a Faradaic efficiency of over 80% without showing any sign of deactivation. This performance and durability could be decoupled into separate effects of Sn doping and Nb2O5 layer via in-depth surface characterization and electrochemical analyses. Sn doping increased the donor density (Nd) of bare hematite by a factor of 20 and significantly improved its conductivity, leading to enhanced charge transfer efficiency. The Nb2O5 layer exerted an effect similar to Sn doping because of the diffusion of a fraction of Nb(V) into the hematite lattice during the annealing process at 700 °C. The primary effect of the Nb2O5 layer is to passivate the hematite surface and make the surface more reactive toward the oxygen evolution through water oxidation. These effects are synergistically combined in the dual-modified hematite electrode.

Original languageEnglish
Pages (from-to)591-599
Number of pages9
JournalApplied Catalysis B: Environmental
Volume201
DOIs
Publication statusPublished - 1 Feb 2017

Fingerprint

Hematite
hematite
Doping (additives)
oxidation
Oxidation
Water
water
durability
Passivation
irradiation
Durability
Irradiation
ferric oxide
annealing
Photocurrents
Charge transfer
electrode
conductivity
Annealing
Oxygen

Keywords

  • Oxygen evolution
  • Photoanode modification
  • Photoelectrochemistry
  • Solar fuel
  • Water splitting

ASJC Scopus subject areas

  • Catalysis
  • Environmental Science(all)
  • Process Chemistry and Technology

Cite this

Dual modification of hematite photoanode by Sn-doping and Nb2O5 layer for water oxidation. / Jeon, Tae Hwa; Bokare, Alok D.; Han, Dong Suk; Abdel-Wahab, Ahmed; Park, Hyunwoong; Choi, Wonyong.

In: Applied Catalysis B: Environmental, Vol. 201, 01.02.2017, p. 591-599.

Research output: Contribution to journalArticle

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AB - Porous hematite (α-Fe2O3) films doped with Sn(IV) and coated with an ultrathin (∼2 nm thick) Nb2O5 passivation layer were synthesized, and the photoelectrochemical (PEC) water oxidation performance and durability of the hematite were examined in detail. As compared to hematite samples modified by either doping or passivation, dual-modified hematite exhibited a promising PEC water oxidation performance under AM 1.5 irradiation. A stable photocurrent was maintained under prolonged irradiation over 24 h, while O2 was produced from water with a Faradaic efficiency of over 80% without showing any sign of deactivation. This performance and durability could be decoupled into separate effects of Sn doping and Nb2O5 layer via in-depth surface characterization and electrochemical analyses. Sn doping increased the donor density (Nd) of bare hematite by a factor of 20 and significantly improved its conductivity, leading to enhanced charge transfer efficiency. The Nb2O5 layer exerted an effect similar to Sn doping because of the diffusion of a fraction of Nb(V) into the hematite lattice during the annealing process at 700 °C. The primary effect of the Nb2O5 layer is to passivate the hematite surface and make the surface more reactive toward the oxygen evolution through water oxidation. These effects are synergistically combined in the dual-modified hematite electrode.

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