Department of Electrical and Computer Engineering, University of Alberta, 9211-116 St, Edmonton, AB, Canada T6G 1H9.
Nanotechnology. 2018 Jan 5;29(1):014002. doi: 10.1088/1361-6528/aa9823.
Anodically formed, vertically oriented, self-organized cylindrical TiO nanotube arrays composed of the anatase phase undergo an interesting morphological and phase transition upon flame annealing to square-shaped nanotubes composed of both anatase and rutile phases. This is the first report on heterojunctions consisting of metal nanoparticles (NPs) deposited on square-shaped TiO nanotube arrays (STNAs) with mixed rutile and anatase phase content. A simple photochemical deposition process was used to form Cu, CuPt, and Pt NPs on the STNAs, and an enhancement in the visible light photoelectrochemical water splitting performance for the NP-decorated STNAs was observed over the bare STNAs. Under narrow band illumination by visible photons at 410 nm and 505 nm, Cu NP-decorated STNAs performed the best, producing photocurrents 80% higher and 50 times higher than bare STNAs, respectively. Probing the energy level structure at the NP-STNA interface using ultraviolet photoelectron spectroscopy revealed Schottky barrier formation in the NP-decorated STNAs, which assists in separating the photogenerated charge carriers, as also confirmed by longer charge carrier lifetimes in NP-decorated STNAs. While all the NP-decorated STNAs showed enhanced visible light absorption compared to the bare STNAs, only the Cu NPs exhibited a clear plasmonic behavior with an extinction cross section that peaked at 550 nm.
经阳极氧化形成、垂直取向、自组织的 TiO 纳米管阵列由锐钛矿相组成，在火焰退火后会经历有趣的形态和相转变，形成由锐钛矿相和金红石相组成的方形纳米管。这是首例关于由沉积在具有混合锐钛矿和金红石相含量的方形 TiO 纳米管阵列（STNAs）上的金属纳米颗粒（NPs）组成的异质结的报道。采用简单的光化学沉积工艺在 STNAs 上形成 Cu、CuPt 和 Pt NPs，并观察到 NP 修饰的 STNAs 在可见光光解水产氢性能方面优于裸 STNAs。在 410nm 和 505nm 可见光光子的窄带照射下，Cu NP 修饰的 STNAs 的性能最佳，分别产生比裸 STNAs 高 80%和 50 倍的光电流。使用紫外光电子能谱探测 NP-STNA 界面的能级结构，发现 NP 修饰的 STNAs 中形成肖特基势垒，这有助于分离光生载流子，这也得到 NP 修饰的 STNAs 中载流子寿命更长的证实。虽然所有 NP 修饰的 STNAs 与裸 STNAs 相比都表现出增强的可见光吸收，但只有 Cu NPs 表现出明显的等离子体行为，消光截面在 550nm 处达到峰值。
