摘要：Covalent organic frameworks(COFs)have lately emerged as a blooming class of potential materials for photocatalytic water splitting because of their high crystallinity,huge surface areas,and structural ***,the photocatalytic performance for most pure COFs face some limitations factors,such as the significant recombination of photogenerated carriers and slow charge ***,a novel thioether-functionalized pyrene-based COF(S_(4)-COF)was effectively produced and chosen as a support for the immobilization of ultrafine gold nanoparticles(Au NPs).S_(4)-COF photocatalyst with Au as cocatalyst demonstrates remarkable photocatalytic activity with a H_(2) generation rate of 1377μmol g^(−1) h^(−1) under visible light(>420 nm),which is ca.4.5-fold increase comparing to that of pure S_(4)-COF(302μmol g^(−1) h^(−1)).Au NPs anchored on S_(4)-COF possess an ultrafine size distribution ranging from 1.75 to 6.25 nm with an average size centered at 3.8 nm,which benefits from the coordination interaction between thioether groups and ***,the produced Au@S_(4)-COF can generate a stable photocatalytic H_(2) generation during the four recycles and preserve its crystallinity structure after the stability *** Au NPs anchored on the S_(4)-COF photocatalyst can greatly accelerate the separation of photogenerated carriers and increase charge transfer because of the combined function of Au NPs and thioether *** a method can not only prevent the aggregation of Au NPs onto thioether-containing COFs to achieve long-term photostability but also allow uniform dispersion for an ordered structure of *** work provides a rational strategy for designing and preparing COF-based photocatalysts for solar-driven H_(2) production.

摘要：由于析氧反应的内在动力学缓慢,开发高效的光催化析氧反应催化剂,以利用太阳能进行光催化分解水产氧,面临着巨大的挑战.本研究设计了一种新型的“主-客体”光催化系统,通过简单的预负载将单位点钌(Ru)分子催化剂引入共价三嗪框架(CTFs)的孔道内.其中,CTFs作为光敏剂和光催化载体,单核钌配合物Ru-bda-Isoq作为分子水氧化催化剂.在可见光照射下,Ru-bda-Isoq@CTF-Bph在5h内平均析氧速率达到2308μmol g^(-1)h^(-1),其性能超过了大多数有机光催化剂.同时,研究还发现多孔光敏剂与分子催化剂之间的结构匹配起着非常关键的作用.该体系具有广泛的适用性,这一策略有助于高效水氧化光催化系统的设计.

摘要：Porous organic polymers(POPs)are an emerging class of porous materials,having many promising applications in a variety of *** them,covalent triazine frameworks(CTFs)featuring conjugated and porous structures can be well applied in *** achieve high optoelectronic performance,usually the design and synthesis of CTFs based on appropriate building blocks is *** we report the synthesis of two fluorescent CTFs based on typical fluorescent building blocks,in which CTF-Py constructed from a pyrene(Py)building block was reported for the first time,showing prospective applications in the sensing of nitroaromatics with high sensitivity,and photocatalytic water splitting and carbon dioxide reduction with high performance in comparison with other porous organic materials.

摘要：氢能是重要的清洁能源,如何低成本获取氢能是其走向实际应用的重要挑战.利用太阳能驱动半导体光催化剂分解水制氢是解决这一挑战的理想途径之一.光催化全解水包括两个半反应,即析氢反应(HER)和析氧反应(OER).其中,光催化OER半反应涉及四个电子的转移(包括O–H键断裂和O–O键形成),其动力学速率远低于两电子转移的HER半反应,因此被认为是光催化全解水的决速步骤.欲实现高效光催化全解水,首先需解决光催化OER半反应动力学缓慢的问题,因此开发高效的OER光催化剂成为当务之急.受单原子催化剂的启发,本文设计并合成了联吡啶基共价三嗪框架(CTF-Bpy),因CTF-Bpy骨架上存在周期性的联吡啶官能团作为金属配位位点,并且有很好的结晶性以及合适的能带结构,是良好的光催化OER反应载体材料.然后通过简单的浸渍配位处理,将单位点的钴作为助催化剂引入到CTF-Bpy中,并用于光催化OER.X射线光电子能谱和X射线近边吸收光谱结果表明,钴是以单位点的Co^(2+)形式存在的.在可见光(λ≥420 nm)照射下,CTF-Bpy-Co在初始1 h内的平均析氧速率为3359μmolg^(–1)h^(–1),5 h内的平均析氧速率为1503μmolg^(–1)h^(–1),光催化性能超过大多数多孔有机聚合物基光催化剂.在420 nm单波长氙灯照射下,CTF-Bpy-Co的光催化析氧表观量子产率(AQY)为0.466%.此外,CTF-Bpy-Co可实现连续析氧40 h,总析氧量可达到180μmol.为明确单位点钴在光催化OER中所起的重要作用,采用相同钴含量的不同形式钴基粒子(游离的Co^(2+),Co,CoO,Co_(2)O_(3)和Co(OH)_(2))作为助催化剂引入CTF-Bpy骨架中进行对比.结果发现,配位的CTF-Bpy-Co表现出最好的光催化析氧效果,表明单位点钴在光催化OER中具有较大的优势.采用密度泛函理论研究了CTF-Bpy-Co的差分电荷密度,并结合上述实验结果提出了CTF-Bpy-Co光催化OER的机理:在可见光激发下,CTF-Bpy-Co光催化剂产生了光生电子和空穴,然后光生电子和空穴被分离并转移到光催化剂与水之间的界面.差分电荷密度证实了电子主要分布于三嗪位点周围,被Ag^(+)迅速捕获生成Ag纳米颗粒;空穴主要分布在Bpy-Co附近,单位点钴可以作为空穴的捕获中心,迅速将Co^(2+)氧化为更高价态的Co^(3+),并与界面上的水分子发生氧化反应产生氧气回到基态,完成整个光催化分解水反应循环.综上所述,为了解决光催化OER的瓶颈问题,本文提出了在催化剂中引入单位点金属助催化剂的策略,显著提升了光催化析氧性能.本研究也为实现更高效的无牺牲剂条件下的光催化全解水提供参考.