Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami Osawa, Hachioji, Tokyo 192-0397, Japan.
Dalton Trans. 2019 Jan 2;48(2):688-695. doi: 10.1039/c8dt03502d.
The dye-sensitized photoelectrochemical cells (DSPECs) incorporating a family of ruthenium complexes [RuII(bipyP)(bipy)2] (P1), [RuII(bipyP)(dmb)2] (P2), [RuII(bipyP)(dtbb)2] (P3) and [RuII(bipyP)(dnb)2] (P4), where bipyP = 2,2'-bipyridine-4,4'-diphosphonic acid, bipy = 2,2'-bipyridine, dmb = 4,4'-dimethyl-2,2'-bipyridine, dtbb = 4,4'-di-tert-butyl-2,2'-bipyridine, and dnb = 4,4'-dinonyl-2,2'-bipyridine, were fabricated in a dye-only system (do-DSPEC) and in a system where the electrolyte solution was loaded with EDTA sacrificial agent (sa-DSPEC). The increasing number of the alkyl chains of the ancillary bipy ligand shifts the ground- and excited-state potentials to the more negative values, although the introduction of the longer nonyl chain in P4 shows the opposite effect. In do-DSPECs, the photocurrent and hydrogen production performance follows the order P4 > P3 > P2 > P1, which correlates well with the degree of the excited-state quenching by electron injection to the conduction band of TiO2. The photoelectrochemistry of the sa-DSPECs reveals 10 times as many photocurrents as that measured in do-DSPECs, suggesting the ability of the hole to oxidize EDTA molecule. The hydrogen production performance of sa-DSPECs over five hours follows the order P2 > P1 > P3 > P4, which is consistent with the RuIII/RuII reorganization energies and the hole mobility on the TiO2 surface. The present study provides evidence that the subtle alkyl chain variation of the ruthenium photosensitizers can fine tune the electron injection capacity, RuIII/RuII self-exchange energetics and photostability of the complexes, which significantly influence the performance of the DSPECs.
将一系列钌配合物[RuII(bipyP)(bipy)2]（P1）、[RuII(bipyP)(dmb)2]（P2）、[RuII(bipyP)(dtbb)2]（P3）和[RuII(bipyP)(dnb)2]（P4）掺入染料敏化光电化学电池（DSPEC）中，其中 bipyP = 2,2'-联吡啶-4,4'-二膦酸，bipy = 2,2'-联吡啶，dmb = 4,4'-二甲基-2,2'-联吡啶，dtbb = 4,4'-二叔丁基-2,2'-联吡啶，dnb = 4,4'-二正辛基-2,2'-联吡啶，在染料仅系统（do-DSPEC）和电解质溶液中负载 EDTA 牺牲剂的系统（sa-DSPEC）中制备。辅助 bipy 配体的烷基链数目的增加将基态和激发态电势移向更负的值，尽管在 P4 中引入更长的壬基链显示出相反的效果。在 do-DSPEC 中，光电流和氢气产生性能遵循 P4 > P3 > P2 > P1 的顺序，这与电子注入到 TiO2 导带中对激发态的淬灭程度很好地相关。sa-DSPEC 的光电化学表明，光电流是在 do-DSPEC 中测量的光电流的 10 倍，这表明空穴能够氧化 EDTA 分子。sa-DSPEC 在五个小时内的氢气产生性能遵循 P2 > P1 > P3 > P4 的顺序，这与 RuIII/RuII 重组能和 TiO2 表面上的空穴迁移率一致。本研究提供的证据表明，钌敏化剂的细微烷基链变化可以精细调节电子注入能力、RuIII/RuII 自交换能和配合物的光稳定性，这对 DSPEC 的性能有显著影响。
