Department of Chemical Engineering, Center for Electrochemistry, Texas Materials Institute, Center for Nano and Molecular Science, University of Texas at Austin, 1 University Station C0400 Austin, Texas 78712-0231, USA.
Nano Lett. 2012 Jan 11;12(1):26-32. doi: 10.1021/nl2028188. Epub 2011 Dec 1.
We report hydrothermal synthesis of single crystalline TiO(2) nanowire arrays with unprecedented small feature sizes of ~5 nm and lengths up to 4.4 μm on fluorine-doped tin oxide substrates. A substantial amount of nitrogen (up to 1.08 atomic %) can be incorporated into the TiO(2) lattice via nitridation in NH(3) flow at a relatively low temperature (500 °C) because of the small cross-section of the nanowires. The low-energy threshold of the incident photon to current efficiency (IPCE) spectra of N-modified TiO(2) samples is at ~520 nm, corresponding to 2.4 eV. We also report a simple cobalt treatment for improving the photoelectrochemical (PEC) performance of our N-modified TiO(2) nanowire arrays. With the cobalt treatment, the IPCE of N-modified TiO(2) samples in the ultraviolet region is restored to equal or higher values than those of the unmodified TiO(2) samples, and it remains as high as ~18% at 450 nm. We propose that the cobalt treatment enhances PEC performance via two mechanisms: passivating surface states on the N-modified TiO(2) surface and acting as a water oxidation cocatalyst.
我们报告了在掺氟氧化锡基底上通过水热合成具有前所未有的小尺寸（约 5nm）和高达 4.4μm 的单晶 TiO2 纳米线阵列。由于纳米线的横截面较小，在 NH3 流中于相对较低的温度（500°C）下通过氮化可以将大量的氮（高达 1.08 原子%）掺入 TiO2 晶格中。氮掺杂 TiO2 样品的入射光子到电流效率（IPCE）光谱的低能量阈值在约 520nm，对应于 2.4eV。我们还报告了一种简单的钴处理方法，用于提高我们的氮掺杂 TiO2 纳米线阵列的光电化学（PEC）性能。通过钴处理，氮掺杂 TiO2 样品在紫外区域的 IPCE 恢复到与未改性 TiO2 样品相等或更高的值，在 450nm 时仍高达约 18%。我们提出钴处理通过两种机制增强了 PEC 性能：钝化氮掺杂 TiO2 表面的表面态和作为水氧化共催化剂。
