Code 6100, Chemistry Division and ‡Code 6300, Material Science & Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States.
Langmuir. 2017 Sep 19;33(37):9444-9454. doi: 10.1021/acs.langmuir.7b01117. Epub 2017 Aug 1.
We use plasmonic Au-TiO aerogels as a platform in which to marry synthetically thickened particle-particle junctions in TiO aerogel networks to Au∥TiO interfaces and then investigate their cooperative influence on photocatalytic hydrogen (H) generation under both broadband (i.e., UV + visible light) and visible-only excitation. In doing so, we elucidate the dual functions that incorporated Au can play as a water reduction cocatalyst and as a plasmonic sensitizer. We also photodeposit non-plasmonic Pt cocatalyst nanoparticles into our composite aerogels in order to leverage the catalytic water-reducing abilities of Pt. This Au-TiO/Pt arrangement in three dimensions effectively utilizes conduction-band electrons injected into the TiO aerogel network upon exciting the Au SPR at the Au∥TiO interface. The extensive nanostructured high surface-area oxide network in the aerogel provides a matrix that spatially separates yet electrochemically connects plasmonic nanoparticle sensitizers and metal nanoparticle catalysts, further enhancing solar-fuels photochemistry. We compare the photocatalytic rates of H generation with and without Pt cocatalysts added to Au-TiO aerogels and demonstrate electrochemical linkage of the SPR-generated carriers at the Au∥TiO interfaces to downfield Pt nanoparticle cocatalysts. Finally, we investigate visible light-stimulated generation of conduction band electrons in Au-TiO and TiO aerogels using ultrafast visible pump/IR probe spectroscopy. Substantially more electrons are produced at Au-TiO aerogels due to the incorporated SPR-active Au nanoparticle, whereas the smaller population of electrons generated at Au-free TiO aerogels likely originate at shallow traps in the high surface-area mesoporous aerogel.
我们使用等离子体 Au-TiO 气凝胶作为平台，将 TiO 气凝胶网络中的合成增稠粒子-粒子结与 Au∥TiO 界面结合，然后研究它们在宽带（即 UV+可见光）和仅可见光激发下对光催化氢（H）生成的协同影响。通过这种方式，我们阐明了掺入的 Au 可以发挥的双重功能，即作为水还原助催化剂和等离子体敏化剂。我们还将非等离子体 Pt 助催化剂纳米颗粒光沉积到我们的复合气凝胶中，以利用 Pt 的催化水还原能力。这种 Au-TiO/Pt 在三维空间中的排列有效地利用了在 Au∥TiO 界面激发 AuSPR 时注入 TiO 气凝胶网络的导带电子。气凝胶中广泛的纳米结构高表面积氧化物网络提供了一个矩阵，该矩阵在空间上分离但在电化学上连接等离子体纳米颗粒敏化剂和金属纳米颗粒催化剂，进一步增强了太阳能燃料光化学。我们比较了添加 Pt 助催化剂前后 Au-TiO 气凝胶的 H 生成光催化速率，并证明了 SPR 产生的载流子在 Au∥TiO 界面与下游 Pt 纳米颗粒助催化剂之间的电化学连接。最后，我们使用超快可见泵/IR 探针光谱研究了 Au-TiO 和 TiO 气凝胶中导带电子在可见光刺激下的产生。由于掺入的 SPR 活性 Au 纳米颗粒，Au-TiO 气凝胶中产生了更多的电子，而在没有 Au 的 TiO 气凝胶中产生的电子数量较少，可能源自高表面积介孔气凝胶中的浅陷阱。
