TiO2 nanotubes decorated with Au nanoparticles for Photocatalytic Hydrogen Generation under UV-Visible and Visible Light Irradiations

Abstract The development of stable and active TiO2 nanotubes (NTs) decorated with plasmonic gold nanoparticles (Au NPs) represents a strategy for charge-transfer processes improvements. However, organic capping ligands used for Au NPs synthesis usually remain on the surface of the metal, leading to poor Schottky junctions between Au and TiO2. Herein, we report on the synthesis of a nanotubular matrix of TiO2 decorated with gold without the need of ligands. The Au NPs mean diameter (12 nm) was similar to all the samples prepared, no matter the metal loading. Such materials enabled to use the metal as a cocatalyst for photogeneration of H2under UV and visible light irradiations. We found an optimum metal loading (2.6 wt% Au) that enabled an improvement of 760% on the H2 production when compared to the bare TiO2 NTs under UV-Vis irradiation. In addition, such catalyst was able to perform photogeneration of H2 under visible irradiation, which was not conceivable before the metal immobilization over the TiO2 NTs. The yield obtained was comparable to the observed when the catalyst was used under UV-Vis conditions. The produced materials were fully characterized by UV-Vis, XRD, TEM, and SEM.

摘要 采用等离子体金纳米颗粒（Au NPs）修饰稳定且高活性的二氧化钛纳米管（NTs），是优化电荷转移过程的可行策略。然而，用于金纳米颗粒合成的有机封端配体通常会残留于金属表面，导致金与二氧化钛之间的肖特基结性能不佳。本文报道了无需配体即可制备负载金的二氧化钛纳米管基体材料。无论金属负载量如何，所有制备样品的金纳米颗粒平均粒径均稳定在12 nm。此类材料可将金属作为助催化剂，用于紫外及可见光辐照下的光催化产氢过程。研究发现最优金属负载量为2.6 wt% Au，在紫外-可见光辐照下，其产氢性能较裸二氧化钛纳米管提升760%。此外，该催化剂可在可见光辐照下实现光催化产氢，而此前在二氧化钛纳米管表面负载金属之前，该过程无法实现。其产氢收率与该催化剂在紫外-可见光条件下使用时的观测结果相当。所制备的材料通过紫外-可见光谱、X射线衍射（XRD）、透射电子显微镜（TEM）及扫描电子显微镜（SEM）完成了全面表征。