基于两个钴(Ⅱ)配合物分子器件的光催化产氢性能及电子转移机理

Photocatalytic H2 evolution performance and electron transfer mechanism based on two novel cobalt(Ⅱ)photochemical molecular devices

本文以钴(II)配合物([Co(dmbpy)_(3)]Cl_(2)(dmbpy=4,4'-dimethyl-2,2'-联吡啶基)和有机染料罗丹明-6G(R-6G)及曙红Y(EY^(2-))合成了两个分子器件D1和D2,通过MS、^(1)HNMR、元素分析等手段目标分子器件的结构进行表征,并通过荧光光谱和循环伏安实验测试了其性能。然后,以目标分子器件为光催化剂,三乙胺(TEA)为牺牲剂,在体积比为1∶1的CH_(3)CN/H_(2)O溶液中,构建了均相的光催化产氢体系。在D2浓度为4×10^(-4)mol·L^(-1),TEA浓度为25%(V/V),pH为10.0的最佳产氢条件下,经过150min的可见光(λ>420 nm)照射,最大产氢量为205.5±9.5μmol(25TON,vs.D2)。此外,还通过荧光光谱实验和循环伏安实验简要讨论了本文所构建的产氢体系的电子转移机理。结果表明,本文所构建的产氢体系可能需要经历三个途径(A,B和C)来实现光催化产氢,而EY^(2-)-[b]-Co^(III)H是最重要的产氢中间体。

Two photochemical molecular devices(PMDs)D1 and D2 have been synthesized by the self-assembly of cobalt(Ⅱ)complex[Co(dmbpy)_(3)]Cl_(2)(dmbpy=4,4’-dimethyl-2,2’-bipyridyl)and organic xanthene dye EosinY(EY^(2-))and Rhodamine-6G(R-6G),the structures were characterized by MS,^(1)HNMR,Elemental analyses,and the performances were tested by fluorescence spectra and cyclic voltammetry.Then,a homogeneous photocatalytic system was constructed for hydrogen production using the target PMD as photocatalyst and trimethylamine(TEA)as a sacrificial electron donor in CH_(3)CN/H_(2)O(V∶V,1∶1).The maximum H_(2) evolution of 205.5±9.5μmol(25TON,vs.D2)was recorded under the optimal conditions with D2 of 4×10^(-4) mol·L^(-1),TEA of 25%(V/V)and pH 10.0 in CH_(3)CN/H_(2)O(V∶V,1∶1)after 150min of irradiation(λ>420 nm).Furthermore,the mechanism of H_(2) evolution in the present system was also briefly discussed by fluorescence spectrum and cyclic voltammetry.The mechanism investigation indicated that three pathways(A,B and C)might be undergone three pathways to realize photocatalytic hydrogen evolution for the present hydrogen production system,and EY^(2-)-[b]-Co^(III)H species is the most important hydrogen production intermediate.