Development of an efficient photocatalytic system for CO2 reduction using rhenium(l) complexes based on mechanistic studies
Development of an efficient photocatalytic system for CO2 reduction using rhenium(l) complexes based on mechanistic studies
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DOI：
10.1021/ja077752e
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发表时间：
2008-02-13
影响因子：
15
通讯作者：
Ishitani, Osamu
中科院分区：
文献类型：
--
作者：
Takeda, Hiroyuki;Koike, Kazuhide;Ishitani, Osamu
通过对三种铼(l)配合物fac[Re(bpy)(CO)(3) l] (l = SCN- (1-NCS)、Cl- （1-CI)和CN- (1-CN)）光催化还原CO2的反应机理进行了详细的比较研究。相应的单电子还原物（OER）在反应中起着两个重要作用：(a)在失去单齿配体(L)后捕获CO2， （b)在不失去L的情况下，另一个OER将第二个电子提供给CO2。在1-NICS的情况下，相应的OER在光催化反应中具有这两种能力，导致CO形成效率更高（量子产率为0.30），而1-CI的量子产率为0.16），因为OER物种的寿命太短，无法在光催化反应中积累。另一方面，1-CN没有表现出光催化能力，因为相应的OER物质不能解离CN-配体。在此基础上，采用fac-[Re(bpy)(CO)(3)(CH3CN)]（+）和fac-[re4,4 '-(MeO)(2)bpy}(CO)(3){P(OEt)(3)}]（+）的混合体系成功地开发了最有效的光催化体系，其CO生成的优化量子产率为0.59。
The reaction mechanism of photocatalytic CO2 reduction using rhenium(l) complexes has been investigated by means of a detailed comparison of the photocatalyses of three rhenium(l) complexes, fac[Re(bpy)(CO)(3)L] (L = SCN- (1-NCS), Cl- (1-CI), and CN- (1-CN)). The corresponding one-electron-reduced species (OER) of the complexes play two important roles in the reaction: (a) capturing CO2 after loss of the monodentate ligand (L) and (b) donation of the second electron to CO2 by another OER without loss of L. In the case of 1-NICS, the corresponding OER has both of the capabilities in the photocatalytic reaction, resulting in more efficient CO formation (with a quantum yield of 0.30) than that of 1-CI (quantum yield of 0.16), for which OER species have too short a lifetime to accumulate during the photocatalytic reaction. On the other hand, 1-CN showed no photocatalytic ability, because the corresponding OER species does not dissociate the CN- ligand. Based on this mechanistic information, the most efficient photocatalytic system was successfully developed using a mixed system with fac-[Re(bpy)(CO)(3)(CH3CN)](+) and fac-[Re4,4'-(MeO)(2)bpy}(CO)(3){P(OEt)(3)}](+), for which the optimized quantum yield for CO formation was 0.59.