文献类型：期刊文献

英文题名：Improvement of Hematite as Photocatalyst by Doping with Tantalum

作者：Zhang, Xinsheng[1,2];Li, Huicheng[2];Wang, Shijun[1];Fan, Fu-Ren F.[1];Bard, Allen J.[1]

机构：[1]Univ Texas Austin, Dept Chem & Biochem, Ctr Electrochem, Austin, TX 78712 USA;[2]E China Univ Sci & Technol, State Key Lab Chem Engn, Shanghai 200237, Peoples R China

年份：2014

卷号：118

期号：30

起止页码：16842

外文期刊名：JOURNAL OF PHYSICAL CHEMISTRY C

收录：;EI(收录号：20143318053138);WOS:【SCI-EXPANDED(收录号:WOS:000339930900066)】；

基金：We thank Drs. Yanqing Cong, Hyun Seo Park, Chongyang Liu, Xiaole (Joy) Chen, Sung Ki Cho, and others in this group for their helpful discussions. We also thank Dr. Vincent Lynch, Department of Chemistry and Dr. Hugo Steinfink, Department of Chemical Engineering for their valuable advice about XRD characterization. X.Z. was financially supported by the National Scholarship Fund of the China Scholarship Council (No. 2009674514). This work was funded by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences of the U.S. Department of Energy through Grant DE-FG02-09ER16119.

语种：英文

外文关键词：Fluorine compounds - Nanocomposites - Tin oxides - Scanning probe microscopy - Photoelectrochemical cells - Scanning electron microscopy - Oxide films - Semiconductor doping - Substrates - Tantalum oxides

摘要：The use of tantalum as a highly effective dopant for hematite photoelectrochemistry (PEC) has shown contradictory results in previous reports. We show here through screening of different compositions by scanning electrochemical microscopy that Ta doping significantly improves the PEC performance of dropcast films on fluorine-doped tin oxide (FTO). In studies with larger electrodes, a 2% Ta-doped hematite photoanode fabricated at 500 degrees C shows the highest improvement of photoactivity, which is similar to 32 times higher than pure hematite even under visible light. At fabrication temperature higher than 500 degrees C (e.g., 600, 680 degrees C), the substrate FTO becomes more resistive and the dopant Ta prefers to segregate from the bulk phase (alpha-Fe2O3) and forms tantalum fluoride oxide (TaO2F), which may act as charge-carrier recombination centers, and the corresponding Ta-doped samples show much lower photoactivities. Ta-doped hematite samples show stronger (110) diffraction as compared with the pure alpha-Fe2O3. We show that the doping of Ta induced a preferential growth along the {001} basal plane, which has been reported to have good conductivity. We found the conductivity of the Ta-doped hematite was improved up to at least about one order of magnitude after the incorporation of Ta, with the improved carrier mobility decreasing recombination of the photogenerated holes and electrons.