Understanding the photocatalytic–activity–defects relationship of titanium oxynitride nanotubes (TiON-NTs) is important for tailoring their photocatalytic performance. Herein, we fabricated highly ordered and vertically aligned nanotube arrays of TiON-NT-functionalized with iridium nanoparticles denoted as (Ir/TiON-NTs) for solar-driven water splitting. Positron annihilation lifetime spectroscopy (PALS) and variable-energy positron annihilation spectroscopy (VEPAS) were performed to quantify the vacancy-type defects of Ir/TiON-NTs relative to TiON-NTs and TiO₂-NTs. The results display that the Ir/TiON-NTs exhibit abundant defects such as small nitrogen vacancies, larger size vacancy clusters, and small voids. The obtained photocurrent density of the Ir/TiON-NTs (11.3 mA cm⁻²) is about 3.97, 5, and 11.89 times higher than that of Ir/TiO₂-NTs, TiON-NTs, and TiO₂-NTs, respectively. The Mott–Schottky analysis revealed the highest significant negative shift in the band potential and the lowest donor density of Ir/TiON-NTs compared to its counterparts. This result is attributed to the unique structural and compositional merits of Ir/TiON-NTs despite the abundant defects, which delay the charge recombination and improve the photocatalytic activity. The presented study may open new frontiers on engineering the defects of metal oxynitrides with metal-based catalysts for photocatalytic applications.

中文翻译：

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铱纳米粒子敏化的氮氧化钛纳米管的量身定制制造，用于太阳能驱动的水分解：光催化-活性-缺陷关系的实验见解

了解氧氮化钛纳米管（TiON-NTs）的光催化-活性-缺陷关系对于调整其光催化性能非常重要。在本文中，我们制备了高度有序且垂直排列的用铱纳米粒子表示的（Ir / TiON-NTs）官能化的TiON-NT，用于太阳能驱动的水分解。进行正电子an没寿命谱（PALS）和可变能量正电子an没谱（VEPAS）来量化Ir / TiON-NTs相对于TiON-NTs和TiO ₂ -NTs的空位型缺陷。结果表明，Ir / TiON-NTs表现出大量的缺陷，例如较小的氮空位，较大的空位团簇和较小的空隙。获得的Ir / TiON-NTs的光电流密度（11.3 mA cm ^-2）分别比Ir / TiO ₂ -NTs，TiON-NTs和TiO ₂ -NTs高3.97倍，5倍和11.89倍。莫特-肖特基分析显示，与之相比，Ir / TiON-NTs的带电势具有最高的显着负移，而Ir / TiON-NTs的供体密度最低。尽管存在大量缺陷，但该结果归因于Ir / TiON-NTs的独特结构和组成优点，从而延迟了电荷重组并提高了光催化活性。提出的研究可能为利用光催化应用的金属基催化剂工程化金属氧氮化物的缺陷开辟新的领域。