New tricks for an old dog: Visible light-driven hydrogen production from water catalyzed by fac-and mer-geometrical isomers of tris(thiosemicarbazide) cobalt(Ⅲ)  

面式、经式异构体的钴-氨基硫脲配合物作为催化剂应用于可见光催化分解水产氢（英文）

作　　者：Yang Zhao Yongheng Wang Qiaoyu Wu Jinqing Lin Shenghui Wu Wenjuan Hou Ruibo Wu Genggeng Luo 赵阳;王永恒;吴荞宇;林金清;吴升晖;侯文娟;巫瑞波;骆耿耿(华侨大学材料科学与工程学院,福建厦门361021;中山大学药学院,广东广州510006;华侨大学分析测试中心,福建厦门361021)

机构地区：[1]College of Materials Science and Engineering, Huaqiao University, Xiamen 361021, Fujian, China [2]Instrumental Analysis Center, Huaqiao University, Xiamen 361021, Fujian, China [3]School of Pharmaceutical Sciences, East Campus, Sun Yat‐sen University, Guangzhou 510006, Guangdon, China

出　　处：《Chinese Journal of Catalysis》2018年第3期517-526,共10页催化学报（英文）

基　　金：supported by the National Natural Science Foundation of China (21641011, 21773313);the Natural Science Foundation of Fujian Province (2015J01053, 2016J01060);Program for New Century Excellent Talents in Fujian Province University;Promotion Program for Young and Middle-aged Teacher in Science, Technology Research of Huaqiao University (ZQN-PY104)~~

摘　　要：Increasing interest has been paid to the development of earth‐abundant metal complexes as promising surrogates of platinum for the electrocatalytically and photocatalytically driven hydrogen evolution reaction.In this work,we report on molecular H2‐evolving catalysts based on two octahedral complexes of cobalt thiosemicarbazide,fac‐[Co(Htsc)3]Cl3·3H2O(C1,Htsc=thiosemicarbazide)and mer‐[Co(Htsc)3]Cl3·4H2O(C2),which have facial(fac)and meridional(mer)geometry,respectively.Electrochemical studies confirmed that both C1and C2are active electrocatalysts in MeOH solution using acetic acid as the proton source,with the same overpotential of^640mV and TOF of^210s–1.The complex C1also exhibits electrocatalytic activity for hydrogen evolution reaction in aqueous media free of organic solvent with a moderate overpotential(560mV).Visible light‐driven hydrogen evolution experiments were carried out in combination with fluorescein as photosensitizer and triethylamine as sacrificial reductant in homogeneous environments.Our studies showed that both C1and C2can be used as efficient proton‐reduction catalysts in purely aqueous solution and have the same photocatalytic activities.A TOF of125h–1with a TON of900for photocatalytic H2generation using C1and C2in water were achieved for the noble‐metal‐free homogeneous system.It should be noted that this is the first reported study investigating the effect on the catalytic hydrogen production performance of using fac‐and mer‐isomers of molecular catalysts.近年来,作为替代贵金属铂催化剂的铁、钴和镍等非贵金属配合物分子催化剂,由于合成容易、结构调控方便以及具有良好的催化活性等特点,成为均相光催化分解水产氢领域的研究热点.其中,钴配合物具有结构简单、成本低廉、容易合成以及具有理想的氧化还原电位等优势,更是光催化分解水产氢领域的优先研究对象.由于稳定性及溶解度的问题,在已报道的研究工作中,大部分钴配合物测试环境均在有机溶剂或有机溶剂/水混合溶剂中.因此,寻找水溶性良好的钴配合物催化剂成为了目前的均相光催化分解水产氢领域的研究焦点之一.在此之前,氨基硫脲配合物已经广泛用于生物和制药等研究,例如:抗氧化、抗菌以及抗病毒等领域.而在人工光合产氢领域采用氨基硫脲配合物作为催化剂的例子则比较罕见.在该项研究中,我们报道了一对水溶性较好(>40 mg mL^(–1),20°C)且具有几何异构特征的八面体钴-氨基硫脲配合物作为光、电催化质子还原产氢的分子催化剂.这对几何异构体分别为:面式异构体[Co(Htsc)_3]Cl_3·3H_2O(C1,Htsc=氨基硫脲配体)和经式异构体[Co(Htsc)_3]Cl_3·4H_2O(C2).我们将几何异构体C1和C2作为水还原分子催化剂,与有机光敏剂荧光素一起构筑了不含贵金属成分的光催化分解水产氢体系.在三乙胺作为牺牲剂及纯水环境中,体系展现出了良好的光催化制氢性能.可见光照15 h后,体系产氢相对于催化剂的TON接近900.对比实验结果表明,具有这对几何异构的C1和C2具有相似的光催化产氢性能,暗示其催化机理的相似性.汞中毒实验结果表明,光催化分解水产氢过程中并没有钴纳米胶体形成,可以确定这是一个均相光催化分解水产氢体系.在纯水环境下,我们将C1和C2与传统的钴配合物(钴肟配合物:[Co(dmgH)_2pyCl](dmg H=丁二酮肟,py=吡啶);联吡啶钴配合物:[Co(bpy)_3Cl_2](bpy=2,2'-联吡啶)

关 键 词：THIOSEMICARBAZIDE Cobalt complexes Molecular catalysis Geometric isomers PHOTOCATALYSIS 

分 类 号：O643.36[理学—物理化学] TQ116.2[理学—化学]