Synthesis of Ta3N5 Nanotube Arrays Modified with Electrocatalysts for Photoelectrochemical Water Oxidation

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• 作者：Yanqing Cong ; Hyun S. Park ; Shijun Wang ; Hoang X. Dang ; Fu-Ren F. Fan ; C. Buddie Mullins ; Allen J. Bard
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：July 12, 2012
• 年：2012
• 卷：116
• 期：27
• 页码：14541-14550
• 全文大小：525K
• 年卷期：v.116,no.27(July 12, 2012)
• ISSN：1932-7455

文摘

Tantalum nitride (Ta₃N₅) is a promising material for photoelectrochemical (PEC) water oxidation with a narrow band gap (2.1 eV) that can effectively utilize visible light in the solar spectrum. Ta₃N₅ nanotube (NT) arrays were synthesized on a Ta foil by electrochemical anodization followed by an ammonia treatment at 800 掳C. The photocurrent of nanostructured Ta₃N₅ was over 3 times higher than that of a dense regular Ta₃N₅ film in 0.1 M Na₂SO₄ aqueous solution at pH 11. Several electrocatalysts (IrO₂ nanoparticles (NPs), Co₃O₄ NPs, cobalt phosphate, and Pt NPs) were used to modify Ta₃N₅ NTs for PEC water oxidation. The photocurrent of Ta₃N₅ NTs modified with IrO₂ and Co₃O₄ was ca. four times higher than that of unmodified NTs. Cobalt phosphate also showed a positive improvement for PEC water oxidation on Ta₃N₅ NTs, whereas Pt was ineffective. Scanning electrochemical microscopy was used to measure the faradaic efficiency of the Ta₃N₅ photoanodes for water oxidation, which can reach as high as 88% for a Co₃O₄鈥揟a₃N₅ NTs photoanode, but is less than 15% at best, for Ta₃N₅ without the electrocatalyst. The results indicate that cobalt oxide and cobalt phosphate are promising candidates as electrocatalysts on Ta₃N₅ for water oxidation because Co is an earth-abundant material.