Photocatalytic Hydrogen Evolution from Hexaniobate Nanoscrolls and Calcium Niobate Nanosheets Sensitized by Ruthenium(II) Bipyridyl Complexes

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• 作者：Kazuhiko Maeda ; Miharu Eguchi ; Seung-Hyun Anna Lee ; W. Justin Youngblood ; Hideo Hata ; Thomas E. Mallouk
• 刊名：Journal of Physical Chemistry C
• 出版年：2009
• 出版时间：May 7, 2009
• 年：2009
• 卷：113
• 期：18
• 页码：7962-7969
• 全文大小：262K
• 年卷期：v.113,no.18(May 7, 2009)
• ISSN：1932-7455

文摘

Hexaniobate nanoscrolls (NS-H₄Nb₆O₁₇) and acid-restacked calcium niobate nanosheets (R-HCa₂Nb₃O₁₀) were compared as oxide semiconductors in photocatalytic assemblies for H₂ production using ethylenediaminetetraacetic acid (EDTA) as a sacrificial electron donor and platinum (Pt) nanoparticles as catalysts. Ru(bpy)₃²⁺ and Ru(bpy)₂(4,4′-(PO₃H₂)₂bpy)²⁺ (bpy = 2,2′-bipyridine) were employed as visible light sensitizers (abbreviated as Ru²⁺ and RuP²⁺, respectively). RuP²⁺, which is anchored by a covalent linkage to the NS-H₄Nb₆O₁₇ surface, functions more efficiently than the electrostatically bound Ru²⁺ complex, because of more efficient electron injection from the excited sensitizer to NS-H₄Nb₆O₁₇. RuP²⁺-sensitized NS-H₄Nb₆O₁₇ and R-HCa₂Nb₃O₁₀ both produce H₂ photocatalytically using visible light (λ > 420 nm) with initial apparent quantum yields of 20−25%. At the optimum sensitizer concentration and Pt loading, the photochemical hydrogen evolution process is primarily limited by the efficiency of light absorption and charge injection from the photoexcited sensitizer into the oxide semiconductor particles. The dependence of the hydrogen evolution rate on Pt loading suggests that the scavenging of conduction band electrons by Pt is substantially faster than charge recombination or EDTA reduction of the oxidized sensitizer under optimized conditions.