Balancing electron transfer rate and driving force for efficient photocatalytic hydrogen production in CdSe/CdS nanorod–[NiFe] hydrogenase assemblies,Energy & Environmental Science

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Balancing electron transfer rate and driving force for efficient photocatalytic hydrogen production in CdSe/CdS nanorod–[NiFe] hydrogenase assemblies
Energy & Environmental Science ( IF 32.4 ) Pub Date : 2017-09-14 00:00:00 , DOI: 10.1039/c7ee01738c
Bryant Chica _{1,

2,

3,

4} , Chang-Hao Wu _{4,

5,

6,

7} , Yuhgene Liu _{1,

2,

3,

4} , Michael W. W. Adams _{4,

6,

7,

8} , Tianquan Lian _{1,

2,

3,

4} , R. Brian Dyer _{1,

2,

3,

4}

Affiliation

We describe a hybrid photocatalytic system for hydrogen production consisting of nanocrystalline CdSe/CdS dot-in-rod (DIR) structures coupled to [NiFe] soluble hydrogenase I (SHI) from Pyrococcus furiosus. Electrons are shuttled to the catalyst by a redox mediator, either methyl viologen (MV²⁺, E₀ = −446 mV vs. NHE) or propyl-bridged 2-2′-bipyridinium (PDQ²⁺, E₀ = −550 mV vs. NHE). We demonstrate nearly equal photoreduction efficiencies for the two mediators, despite extracting ∼100 mV of additional driving force for proton reduction by PDQ²⁺. Femtosecond to microsecond transient absorption reveals that while electron transfer (ET) from the DIR to PDQ²⁺ is slower than for MV²⁺, in both cases the ET process is complete by 1 ns and thus it efficiently outcompetes radiative decay. Long-lived charge separation is observed for both mediators, resulting in similar net efficiencies of photoreduction. Whereas both mediators are readily photoreduced, only PDQ²⁺ yields measurable H₂ production, demonstrating the importance of optimizing the electron shuttling pathway to take advantage of the available reducing power of the DIR excited state. H₂ production in the PDQ²⁺ system is highly efficient, with an internal quantum efficiency (IQE) as high as 77% and a TON_SHI of 1.1 × 10⁶ under mild (RT, pH = 7.35) conditions.

中文翻译：

在CdSe / CdS纳米棒– [NiFe]氢化酶组件中平衡电子传递速率和驱动力以有效地光催化制氢

我们描述了一种混合的光催化制氢系统，该系统由纳米晶体CdSe / CdS点对点（DIR）结构与激烈热球菌[NiFe]可溶性加氢酶I（SHI）耦合而成。电子通过甲基紫精（MV 2 ⁺，E ₀ = -446 mV vs. NHE）或丙基桥接的2-2'-联吡啶（PDQ 2 ⁺，E ₀ = -550 mV ）的氧化还原介体穿梭到催化剂上与NHE）。我们展示了两种介体的光还原效率几乎相同，尽管通过PDQ ²⁺提取了约100 mV的额外驱动力来进行质子还原。。飞秒到微秒的瞬态吸收表明，虽然从DIR到PDQ ^2+的电子转移（ET）慢于MV ²⁺，但在两种情况下ET过程都完成了1 ns，因此它有效地超过了辐射衰减。两种介体均观察到长寿命电荷分离，从而导致相似的净光还原效率。尽管两种介体都易于光还原，但只有PDQ ²⁺产生可测量的H ₂生成量，这表明优化电子穿梭路径以利用DIR激发态的可用还原能力的重要性。PDQ ²⁺中的H ₂产生该系统非常高效，在温和（RT，pH = 7.35）条件下，内部量子效率（IQE）高达77％，TON _SHI为1.1×10 ⁶。

更新日期：2017-10-11

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