高性能光催化剂的构建一直在探索。共价有机骨架(COFs),尤其是酮-胺连接的COF,有很多优点,如可调带隙,π-π堆叠结构,优异的可见光响应能力,高比表面积,载流子的高迁移率,良好的物理和化学稳定性,等等,在光催化太阳能转化和制氢方面显示出强大的潜在应用。两个类似的共价三嗪骨架(CTF),T3H-CTF和T3N-CTF,已在溶剂热条件下通过2,4,6-三羟基苯-1,3,5-三碳烯(MOP)与相应的三嗪基芳胺之间的席夫碱缩合反应合成。对于T3N-CTF,中心三嗪单元的外围芳族连接基是吡啶单元,代替T3H-CTF装置中的苯装置。T3N-CTF的产氢速率(HPR)为6485.05μmolg-1h-1,远高于T3H-CTF(2028.06μmolg-1h-1)。因此,T3N-CTF在405nm处的表观量子产率(AQY)为12.2%,明显高于T3H-CTF(4.12%)。实验和理论结果表明,扩大光吸收范围,扩大的表面积,与T3H-CTF相比,T3N-CTF的电荷载流子的分离和传输效率得到了均匀的诱导,最终促进了可见光诱导的析氢反应(HER)。这项工作提出了一种通过引入吡啶N原子来调节共轭COF的电子特征来增强固有HER活性的新方法。
The construction of high-performance photocatalyst has always been explored. Covalent organic frameworks (COFs), especially keto-amine-linked COFs, have many advantages, such as adjustable bandgaps, π-π stacking structure, excellent response ability to visible light, high specific surface area, high mobility of carrier carriers, good physical and chemical stability, and so on, showing strong potential applications in photocatalytic solar energy conversion and hydrogen production. Two analogous covalent triazine frameworks (CTFs), T3H-CTF and T3N-CTF, have been synthesized via Schiff-base condensation reactions between 2,4,6-trihydroxybenzene-1,3,5-tricarbalehyde (MOP) and the corresponding triazine-based aromatic amines under solvothermal condition. For T3N-CTF, the peripheral aromatic linker to the central triazine unit was the pyridine unit, instead of the benzene unit in the T3H-CTF unit. T3N-CTF had a hydrogen production rate (HPR) of 6485.05 μmol g-1 h-1 , much higher than that of T3H-CTF (2028.06 μmol g-1 h-1 ). Accordingly, T3N-CTF had a much higher apparent quantum yield (AQY) of 12.2 % than that of T3H-CTF (4.12 %) at 405 nm. The experimental and theoretical results showed that the extended light absorption range, enlarged surface area, and enhanced separation and transportation efficiencies of charge carriers of T3N-CTF compared with T3H-CTF were uniformly induced by the introduction of peripheral nitrogen atoms into the skeleton of former CTF, which eventually boosted the visible-light induced hydrogen evolution reaction (HER). The work suggests a new method for enhancing the intrinsic HER activity by modulating the electronic features of the conjugated COFs by the introduction of pyridinic N atoms.