Shylin Sergii I, Pavliuk Mariia V, D'Amario Luca, Fritsky Igor O, Berggren Gustav
Department of Chemistry -Ångström Laboratory, Uppsala University, P. O. Box 523, 75120 Uppsala, Sweden.
Faraday Discuss. 2019 Jul 4;215(0):162-174. doi: 10.1039/c8fd00167g.
An efficient water oxidation system is a prerequisite for developing solar energy conversion devices. Using advanced time-resolved spectroscopy, we study the initial catalytic relevant electron transfer events in the light-driven water oxidation system utilizing [Ru(bpy)3]2+ (bpy = 2,2'-bipyridine) as a light harvester, persulfate as a sacrificial electron acceptor, and a high-valent iron clathrochelate complex as a catalyst. Upon irradiation by visible light, the excited state of the ruthenium dye is quenched by persulfate to afford a [Ru(bpy)3]3+/SO4˙- pair, showing a cage escape yield up to 75%. This is followed by the subsequent fast hole transfer from [Ru(bpy)3]3+ to the FeIV catalyst to give the long-lived FeV intermediate in aqueous solution. In the presence of excess photosensitizer, this process exhibits pseudo-first order kinetics with respect to the catalyst with a rate constant of 3.2(1) × 1010 s-1. Consequently, efficient hole scavenging activity of the high-valent iron complex is proposed to explain its high catalytic performance for water oxidation.
高效的水氧化系统是开发太阳能转换装置的先决条件。利用先进的时间分辨光谱技术，我们研究了以[Ru(bpy)₃]²⁺（bpy = 2,2'-联吡啶）作为光捕获剂、过硫酸盐作为牺牲电子受体以及高价铁笼形配合物作为催化剂的光驱动水氧化系统中与催化相关的初始电子转移事件。在可见光照射下，钌染料的激发态被过硫酸盐猝灭，生成[Ru(bpy)₃]³⁺/SO₄˙⁻对，其笼逃逸产率高达75%。随后，[Ru(bpy)₃]³⁺中的空穴快速转移至FeIV催化剂，在水溶液中生成长寿命的FeV中间体。在存在过量光敏剂的情况下，该过程相对于催化剂呈现出假一级动力学，速率常数为3.2(1) × 10¹⁰ s⁻¹。因此，提出高价铁配合物具有高效的空穴清除活性来解释其对水氧化的高催化性能。
