Photocatalytic hydrogen evolution with ruthenium polypyridine sensitizers: unveiling the key factors to improve efficiencies
Photocatalytic hydrogen evolution with ruthenium polypyridine sensitizers: unveiling the key factors to improve efficiencies
复制标题
DOI：
10.1039/c6dt01221c
复制
发表时间：
2016-01-01
影响因子：
4
通讯作者：
Natali, Mirco
中科院分区：
文献类型：
--
作者：
Deponti, Elisa;Natali, Mirco
旨在评估新分子催化剂的光化学析氢研究通常利用Ru（bpy）（3）（2+）（其中bpy = 2，2 '-联吡啶）作为参考光敏剂，这要归功于其合适的光学和氧化还原性质。原则上，光催化性能的额外改进也可以通过仔细调节基于铼的敏化剂的物理和/或电化学特性来实现。在这里，我们描述了一系列的钌多吡啶配合物作为光敏剂（Ru 1 -4），钴肟催化剂，和抗坏血酸作为牺牲电子供体组成的光催化析氢的均相分子系统。已经解决了联吡啶配体的4，4 '位置的合适的官能化，以改变发色团的氧化还原性质，而不是它们的光学性质。一个仔细和详细的动力学表征的相关过程的基础上，氢的演变的催化剂已被解决，以合理化所观察到的行为。结果表明，由两个2，2 '-联吡啶和一个4，4'-二甲基-2，2 '-联吡啶组成的钌配合物（Ru 2）的性能优于标准的Ru（bpy）（3）（2+）（Ru 1），结合了结构和氧化还原性质的正确平衡，因此可作为新型放氢催化剂研究的替代基准光敏剂。
Photochemical hydrogen evolution studies aimed at evaluating new molecular catalysts have usually exploited Ru(bpy)(3)(2+) (where bpy = 2,2'-bipyridine) as the reference photosensitizer, thanks to its suitable optical and redox properties. In principle, an additional improvement of the photocatalytic performances can be achieved also by a careful adjustment of the photophysical and/or electrochemical characteristics of the ruthenium-based sensitizer. Herein we describe homogeneous molecular systems for photocatalytic hydrogen evolution composed of a series of ruthenium polypyridine complexes as the photosensitizers (Ru1-4), a cobaloxime catalyst, and ascorbic acid as the sacrificial electron donor. Suitable functionalizations of the 4,4' positions of bipyridine ligands have been addressed in order to modify the redox properties of the chromophores rather than their optical ones. A careful and detailed kinetic characterization of the relevant processes at the basis of hydrogen evolving photocatalysis has been addressed to rationalize the observed behavior. The results show that the ruthenium complex involving two 2,2'-bipyridines and one 4,4'-dimethyl-2,2'-bipyridine (Ru2) may outperform the standard Ru(bpy)(3)(2+) (Ru1), combining the right balance of structural and redox properties, thus posing as an alternative benchmark photosensitizer for the study of new hydrogen evolving catalysts.