School of Chemical Engineering, UNSW Australia , Sydney, New South Wales 2052, Australia.
Department of Engineering, Macquarie University , Sydney, New South Wales 2109, Australia.
ACS Appl Mater Interfaces. 2017 Sep 13;9(36):30575-30582. doi: 10.1021/acsami.7b06265. Epub 2017 Aug 31.
Au nanoparticles with different sizes (10, 20, 30, and 50 nm) were synthesized using a seed-assisted approach and anchored onto Pt/TiO employing 3-mercaptopropionic acid as the organic linker. The sizes of the Au nanoparticles were controlled within a narrow range so that the size-dependent surface plasmonic resonance effect on sensitizing Pt/TiO can be thoroughly studied. We found that 20 nm Au nanoparticles (Au) gave the best performance in sensitizing Pt/TiO to generate H under visible-light illumination. Photoelectrochemical measurements indicated that Au-Pt/TiO exhibited the most efficient "hot" electrons separation among the studied catalysts, correlating well with the photocatalytic activity. The superior performance of Au-supported Pt/TiO (Au-Pt/TiO) compared with Au anchored to TiO (Au/TiO) revealed the important role of Pt as a cocatalyst for proton reduction. To elucidate how the visible-light excited hot electrons in Au nanoparticles involved in the proton-reduction reaction process, Au/TiO was irradiated by visible light (λ > 420 nm) with the presence of Pt precursor (HPtCl) in a methanol aqueous solution under deaerated condition. Energy-dispersive X-ray spectroscopy mapping analysis on the recovered sample showed that Pt ions could be reduced on the surfaces of both Au nanoparticles and TiO support. This observation indicated that the generated hot electrons on Au nanoparticles were injected into the TiO conduction band, which were then subsequently transferred to Pt nanoparticles where proton reduction proceeded. Besides, the excited hot electrons could also participate in the proton reduction on Au nanoparticles surface.
采用种子辅助法合成了不同尺寸（10、20、30 和 50nm）的金纳米粒子，并利用 3-巯基丙酸作为有机配体将其锚定在 Pt/TiO 上。金纳米粒子的尺寸控制在较窄的范围内，以便可以彻底研究尺寸相关的表面等离子体共振效应对 Pt/TiO 的敏化作用。我们发现 20nm 金纳米粒子（Au）在敏化 Pt/TiO 产生可见光照射下的 H 方面表现出最佳性能。光电化学测量表明，在研究的催化剂中，Au-Pt/TiO 表现出最有效的“热”电子分离，与光催化活性很好地相关。与锚定在 TiO 上的 Au（Au/TiO）相比，负载 Au 的 Pt/TiO（Au-Pt/TiO）的性能优越，这表明 Pt 作为质子还原助催化剂的重要作用。为了阐明 Au 纳米粒子中可见光激发的热电子如何参与质子还原反应过程，在甲醇水溶液中，在不存在氧的条件下，用 Pt 前体（HPtCl）照射 Au/TiO。对回收样品进行的能谱 X 射线映射分析表明，Pt 离子可以在 Au 纳米粒子和 TiO 载体的表面上被还原。这一观察结果表明，Au 纳米粒子上产生的热电子被注入 TiO 导带中，然后被转移到进行质子还原的 Pt 纳米粒子上。此外，激发的热电子也可以参与 Au 纳米粒子表面的质子还原。
