Effects of Cocatalyst on Carrier Dynamics of a Titanate Photocatalyst with Layered Perovskite Structure

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• 作者：Mitsunori Yabuta ; Tomoaki Takayama ; Kenji Shirai ; Kazuya Watanabe ; Akihiko Kudo ; Toshiki Sugimoto ; Yoshiyasu Matsumoto
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：May 22, 2014
• 年：2014
• 卷：118
• 期：20
• 页码：10972-10979
• 全文大小：365K
• 年卷期：v.118,no.20(May 22, 2014)
• ISSN：1932-7455

文摘

Cocatalysts are usually needed to improve photoconversion efficiency in water splitting with heterogeneous photocatalysts. Here, we show that NiO_x (0 < x < 1) nanoparticles loaded on a layered perovskite, BaLa₄Ti₄O₁₅ (BLT), serve as an effective electron sink. We have measured the time profiles of transient absorption (TA) of BLT with and without loading NiO_x cocatalyst in air and in water in a wide wavelength range from 400 nm to 4 渭m upon excitation with a femtosecond pulse at 266 nm. TA at 4 渭m indicates that photogenerated electrons are rapidly transferred to cocatalyst within 1 ps. The time profile of TA at 402 nm from sub-渭s to 10 ms contributed by surface photoholes is affected by loading of cocatalyst and redox reactions with water. Fittings of the decay profiles of TA at 402 nm with a trap鈥揹etrap kinetic model indicate that the oxidation of water appreciably starts at around 1 ms after the pump pulse, while the reduction of water takes place prior to oxidation in much early time domains. This implies that the redox reactions take place under substantial imbalance between electron and hole densities.