Photochemical reduction of CO2 with ascorbate in aqueous solution using vesicles acting as photocatalysts
Photochemical reduction of CO2 with ascorbate in aqueous solution using vesicles acting as photocatalysts
复制标题
DOI：
10.1039/c3pp50429h
复制
发表时间：
2014-01-01
影响因子：
3.1
通讯作者：
Murata, Shigeru
中科院分区：
文献类型：
--
作者：
Ikuta, Naoya;Takizawa, Shin-ya;Murata, Shigeru
本文报道了一种新型的可见光催化体系，以抗坏血酸(HASC(-))为电子源，将分散在溶液中的DPPC微囊作为光催化剂，将CO2还原为CO。在囊泡中加入了金属络合物[Ru(Dtb)(Bpy)(2)](2+)和Re(Dtb)(CO)(3)Cl(dtb=4，4‘-二叔丁基-2，2’-联吡啶)，它们分别作为光敏剂和催化剂还原CO2。反应始于Ru与HASC(-)的(MLCT)-M-3激发态的还原猝灭，然后电子从还原的Ru络合物转移到Re络合物，得到具有催化CO2还原能力的单电子还原的Re物种。为了寻找最佳的CO生成条件，考察了囊泡溶液中金属络合物和HASC(-)的浓度对CO生成初始速率v(I)的影响。因此，我们得到了与Re催化剂类似的V(I)的3.5mmolh(-1)和190的CO生成转化率。根据v(I)对入射光强的依赖关系，我们得出结论：在该体系中，HASC(-)光催化还原CO2为CO只需要一个光子，并提出HASC(-)不仅向Ru络合物的激发态提供电子，还向参与CO2还原催化循环的Re-CO2加合物提供电子。
We report a novel system of visible-light-driven CO2 reduction to CO in an aqueous solution, in which DPPC vesicles dispersed in the solution act as a photocatalyst using ascorbate (HAsc(-)) as an electron source. In the vesicles metal complexes [Ru(dtb)(bpy)(2)](2+) and Re(dtb)(CO)(3)Cl (dtb = 4,4'-ditridecyl-2,2'-bipyridyl) are incorporated, which act as a photosensitizer and a catalyst for CO2 reduction, respectively. The reaction is initiated with the reductive quenching of the (MLCT)-M-3 excited state of the Ru complex with HAsc(-), followed by an electron transfer from the reduced Ru complex to the Re complex to give a oneelectron reduced Re species having catalytic ability for CO2 reduction. In order to search for optimum conditions for the CO production, the dependence of the initial rate of CO formation, v(i), on the concentration of the metal complexes and HAsc(-) in the vesicle solution was examined. Consequently, we obtained similar to 3.5 mu mol h(-1) and 190 for v(i) and the turnover number for CO formation with respect to the Re catalyst, respectively. On the basis of the dependence of v(i) on the incident light intensity, we have concluded that the photocatalytic reduction of CO2 to CO with HAsc(-) in this system requires only one photon, and propose that HAsc(-)donates an electron not only to the excited state of the Ru complex, but also to the Re-CO2 adduct involved in the catalytic cycle for CO2 reduction.