Effect of Oxygen Content on the Photoelectrochemical Activity of Crystallographically Preferred Oriented Porous Ta3N5 Nanotubes

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• 作者：Sherdil Khan ; Maximiliano J. M. Zapata ; Daniel L. Baptista ; Renato V. Gon莽alves ; Jesum A. Fernandes ; Jairton Dupont ; Marcos J. L. Santos ; S茅rgio R. Teixeira
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：August 27, 2015
• 年：2015
• 卷：119
• 期：34
• 页码：19906-19914
• 全文大小：610K
• ISSN：1932-7455

文摘

Crystallographically preferred oriented porous Ta₃N₅ nanotubes (NTs) were synthesized by thermal nitridation of vertically oriented, thick-walled Ta₂O₅ NTs, strongly adhered to the substrate. The adherence on the substrate and the wall thickness of the Ta₂O₅ NTs were fine-tuned by anodization, thereby helping to preserve their tubular morphology for nitridation at higher temperatures. Samples were studied by scanning electron microscopy, high-resolution electron microscopy, X-ray diffraction, Rietveld refinements, ultraviolet鈥搗isible spectrophotometry, X-ray photoelectron spectroscopy, photoluminescence spectra, and electrochemical techniques. Oxygen content in the structure of porous Ta₃N₅ NTs strongly influenced their photoelectrochemical activity. Structural analyses revealed that the nitridation temperature has crystallographically controlled the preferential orientation along the (110) direction, reduced the oxygen content in the crystalline structure and the tubular matrix, and increased the grain size. The preferred oriented porous Ta₃N₅ NTs optimized by the nitridation temperature presented an enhanced photocurrent of 7.4 mA鈥痗m^鈥? at 1.23 V vs RHE under AM 1.5 (1 Sun) illumination. Hydrogen production was evaluated by gas chromatography, resulting in 32.8 渭mol of H₂ in 1 h from the pristine porous Ta₃N₅ NTs. Electrochemical impedance spectroscopy has shown an effect of nitridation temperature on the interfacial charge transport resistance at the semiconductor鈥搇iquid interface; however, the flat band of Ta₃N₅ NTs remained unchanged.