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Tubular Morphology Surviving and Doping Engineering of Sn/P-Codoped Hematite for Photoelectrochemical Water Oxidation

Abstract

Tubular hematite with high concentration and uniformity doping has been regarded as promising material for photoelectrochemical water oxidation. However, the high-temperature annealing commonly used for activating doped hematite inevitably causes deformation of tubular structure and increase in trap states. In the present work, Sn-doped tubular hematite on fluorine-doped tin oxide (FTO) is successfully evoluted at 750 °C from a Sn-coated FeOOH tube precursor. Sn/P codoping, which is hardly considered for hematite, is also achieved via a gas phase reaction in phosphide atomsphere. The tubular morphology allows dopant diffusing from both inner and outer surface, thus, reducing the doping profile in the radial direction. The even distribution of Sn and P synergetically increases the carrier denisty of hematite by one order of magnitude, which shortens width of depletion layer to ca. 2.3 nm (comparing with 19.3 nm for pristine sample ) and thus leads to prolonged carrier lifetime and efficent charge separation. In addition, such codoping protocol does not introduce extra surface trap states, as evidencd by increased charge injection efficency and surface kinetic analysis using intensity modulated photocurrent spectroscopy (IMPS). As a result, the morphology and doping engineered hematite exhibits the photocurrent of 0.9 mA·cm-2 at 1.23 V and 3.8 mA·cm-2 at 2.0 V vs RHE under AM 1.5 G illumination (100 mW·cm-2) in 1.0 M NaOH, representing 4.5 and 4.8-fold enhancement, respectively, as compared with photocurrent of undoped hematite. Present method is shown to be effective for preparing multi elements doped hematite nanotubes; and might find broad application in development of other nanotubular photoelectrodes with or without doping for efficient and robust water oxidation.

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Publication details

The article was received on 01 Oct 2018, accepted on 05 Dec 2018 and first published on 06 Dec 2018


Article type: Paper
DOI: 10.1039/C8DT03959C
Citation: Dalton Trans., 2018, Accepted Manuscript
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    Tubular Morphology Surviving and Doping Engineering of Sn/P-Codoped Hematite for Photoelectrochemical Water Oxidation

    S. Duan, Y. Geng, X. pan, X. Yao, Y. Zhao, X. Li, C. Tao and D. Qin, Dalton Trans., 2018, Accepted Manuscript , DOI: 10.1039/C8DT03959C

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