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

被引:51
作者
Jeon, Tae Hwa [1 ]
Bokare, Alok D. [1 ]
Han, Dong Suk [2 ]
Abdel-Wahab, Ahmed [2 ]
Park, Hyunwoong [3 ]
Choi, Wonyong [1 ]
机构
[1] Pohang Univ Sci & Technol POSTECH, Sch Environm Sci & Engn, Pohang 37673, South Korea
[2] Texas A&M Univ Qatar, Chem Engn Program, Doha 23874, Qatar
[3] Kyungpook Natl Univ, Sch Energy Engn, Daegu 41566, South Korea
基金
新加坡国家研究基金会;
关键词
Solar fuel; Photoelectrochemistry; Water splitting; Photoanode modification; Oxygen evolution; SENSITIZED SOLAR-CELLS; ALPHA-FE2O3; THIN-FILMS; DOPED HEMATITE; PHOTOELECTROCHEMICAL PERFORMANCE; ELECTRODES; PHOTOOXIDATION; SEMICONDUCTOR; ACTIVATION; DIFFUSION; NANORODS;
D O I
10.1016/j.apcatb.2016.08.059
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Porous hematite (alpha-Fe2O3) films doped with Sn(IV) and coated with ah ultrathin (similar to 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 O-2 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 (N-d) 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 degrees 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. (C) 2016 Elsevier B.V. All rights reserved.
引用
收藏
页码:591 / 599
页数:9
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