在 CdS 量子点-固氮酶系统中调整用于光催化 N2 到 NH3 还原的电子转移途径,Sustainable Energy & Fuels

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在 CdS 量子点-固氮酶系统中调整用于光催化 N2 到 NH3 还原的电子转移途径
Sustainable Energy & Fuels ( IF 5.0 ) Pub Date : 2022-03-30 , DOI: 10.1039/d2se00148a
Artavazd Badalyan ₁ , Zhi-Yong Yang ₁ , Maowei Hu ₁ , T. Leo Liu ₁ , Lance C. Seefeldt ₁

Affiliation

在生物混合系统中将非生物光敏剂与纯化酶相结合，为利用光完成具有挑战性的化学转化提供了一条有希望的途径，并为有效的太阳能-化学能转换的合理光催化系统设计提供了见解。在这项工作中，我们展示了一种混合光催化系统，通过将硫化镉量子点 (CdS QDs) 和来自_Azotobacter vinelandii，由铁蛋白（FeP）和钼铁蛋白（MoFeP）组成。来自 CdS QD 的光激发电子由电子转移介质通过 FeP 传递到催化 MoFeP。整个系统针对 CdS QD 上的配体、介质和反应条件进行了优化。使用 β-巯基乙醇作为 QD 配体可获得最佳结果。介体测试表明 1,1'-双(3-磺基丙基)-4,4'-联吡啶 (SPr) ₂ V (-0.4 V vs. NHE) 支持质子和 N ₂还原为 H ₂和氨催化通过固氮酶。然而，在 1,1'-三亚甲基-2,2'-联吡啶 TQ 存在下（-0.54 V vs.NHE）作为介质，固氮酶催化产生了明显更多的产物。UV-vis 和原位电位研究表明，由于显着更负的溶液电位允许有效减少 FeP，因此 TQ 实现了更好的性能。结果，将吸收的光子转化为氨的量子产率达到 16%，远远超过之前报道的基于固氮酶的系统。这项工作揭示了调整光催化系统中电子转移途径的重要性，并说明了一种有效的光敏剂和 N ₂还原催化剂电子耦合的策略。

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Tailoring electron transfer pathway for photocatalytic N2-to-NH3 reduction in a CdS quantum dots-nitrogenase system

The combination of abiotic photosensitizers with purified enzymes in a biohybrid system offers a promising pathway to utilizing light to accomplish challenging chemical transformations and provides insights into the rational photocatalytic system design for efficient solar-to-chemical energy conversion. In this work, we demonstrate a hybrid photocatalytic system for ammonia production from N₂ by combining cadmium sulfide quantum dots (CdS QDs) and Mo-nitrogenase from Azotobacter vinelandii, composed of the iron protein (FeP) and the molybdenum-iron protein (MoFeP). Photoexcited electrons from the CdS QD are delivered by an electron transfer mediator through the FeP to the catalytic MoFeP. The complete system was optimized for the ligand on the CdS QDs, mediators, and reaction conditions. The best results were achieved with β-mercaptoethanol as a QD ligand. The mediator test revealed that 1,1′-bis(3-sulfonatopropyl)-4,4′-bipyridinium (SPr)₂V (−0.4 V vs. NHE) supports the reduction of protons and N₂ to H₂ and ammonia catalyzed by nitrogenase. However, in the presence of 1,1′-trimethylene-2,2′-bipyridinium TQ (−0.54 V vs. NHE) as a mediator, nitrogenase catalysis resulted in remarkably more products. The UV-vis and in situ potentiometric studies revealed that better performance with TQ is achieved due to the significantly more negative solution potential allowing for efficient reduction of FeP. As a result, the quantum yield for conversion of absorbed photons to ammonia attains 16%, far exceeding that of previously reported nitrogenase-based systems. This work reveals the importance of tuning the electron transfer pathways in photocatalytic systems and illustrates a potent strategy for efficient electronic coupling of a photosensitizer and an N₂ reduction catalyst.

更新日期：2022-03-30

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