The facile design of highly efficient photosensitizers is fundamentally crucial for the construction of efficient photocatalytic H₂-evolving systems. In this work, we employed substituted 2-(thiophen-2-yl) pyridine (C^N) and 2,2′-bipyridine (N^N) ligands to afford a series of iridium complexes. Interestingly, by introducing heavy halogen group -Br, the triplet state lifetime of affording photosensitizer was significantly enhanced to 4273 ns, which is 54 times to that of unmodified one (77 ns). While coupling with Ni-substituted polyoxometalate Ni₄(SiW₉)₂ catalyst and triethanolamine electron donor, the bromine-modified photosensitizer can effectively drive hydrogen generation with a turnover number of ∼ 1400 under visible light irradiation. Spectroscopic studies reveal that the -Br modified iridium complex exhibits larger Stern − Volmer constants for both reductive and oxidative quenching processes. Mechanistic analyses demonstrate the advantages of long-lived excited states and good photostability of bromine modified photosensitizer, the efficient electron transfer process, and the well-matched energy levels between all three catalytic components for efficient hydrogen production.

高效光敏剂的简易设计对于构建高效的光催化产氢_系统至关重要。在这项工作中，我们使用取代的 2-(thiophen-2-yl) 吡啶 (C^N) 和 2,2'-联吡啶 (N^N) 配体来提供一系列铱配合物。有趣的是，通过引入重卤素基团-Br，提供光敏剂的三重态寿命显着提高至 4273 ns，是未修饰光敏剂（77 ns）的 54 倍。与 Ni 取代的多金属氧酸盐Ni ₄ (SiW ₉ ) _2偶联时催化剂和三乙醇胺电子供体，溴改性光敏剂可以在可见光照射下有效地驱动氢气生成，周转数约为1400。光谱研究表明，-Br 修饰的铱络合物在还原和氧化淬火过程中都表现出更大的 Stern − Volmer 常数。机理分析证明了溴改性光敏剂的长寿命激发态和良好的光稳定性、高效的电子转移过程以及所有三种催化组分之间良好匹配的能级以实现高效制氢的优点。