Hot Electron Collection on Brookite Nanorods Lateral Facets for Plasmon-Enhanced Water Oxidation

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• 作者：Alberto Naldoni ; Tiziano Montini ; Francesco Malara ; Marta M. Mróz ; Alessandro Beltram ; Tersilla Virgili ; Chiara L. Boldrini ; Marcello MarelliIsmael Romero-Ocaña ; Juan José Delgado ; Vladimiro Dal Santo ; Paolo Fornasiero
• 刊名：ACS Catalysis
• 出版年：2017
• 出版时间：February 3, 2017
• 年：2017
• 卷：7
• 期：2
• 页码：1270-1278
• 全文大小：619K
• ISSN：2155-5435

文摘

Photocatalytic reactions could enhance the share of chemicals produced through renewable sources. The efficiency of photocatalysts drastically depends on light absorption, on the surface energy of the crystals, and on the properties of the nanobuilding blocks assembled in devices. Here, we show that photoelectrochemical water oxidation on brookite TiO₂ nanorods is greatly enhanced by engineering the location of Au nanoparticles deposition. Brookite photoanodes show a very low onset potential for water oxidation to H₂O₂ of −0.2 V_RHE due to energetics of exposed crystal facets. By combining electrochemical measurements and ultrafast optical spectroscopy, we link the water oxidation activity with electron–hole recombination phenomena. The preferential Au decoration at the electrode/water interface produces highly enhanced photocurrent, while when Au is distributed along the whole film thickness, the activity is depressed with respect to pure brookite. In the latter case, Au nanoparticles act as recombination centers with plasmonic carriers recombining on the same time scale of their generation (fs). Conversely, Au surface decoration enables a hot electrons lifetime 4 orders of magnitude longer (ns) due to efficient hopping on brookite lateral facets, thus providing an efficient path for plasmon-enhanced solar water oxidation.