Yiu Sze-Chun, Ho Po-Yu, Kwok Yan-Yi, He Xiaojie, Wang Yi, Yu Wai-Hong, Ho Cheuk-Lam, Huang Shuping
Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University Hung Hom, Hong Kong, P. R. China.
PolyU Shenzhen Research Institute, Shenzhen, P. R. China.
Chemistry. 2022 Apr 1;28(19):e202104575. doi: 10.1002/chem.202104575. Epub 2022 Mar 4.
Weak light absorption of common Ir(III) complexes (e. g., using phenylpyridine as the ligand) has hindered their applications in photocatalytic hydrogen generation from water as an efficient photosensitizer. To address this issue, a series of cyclometalated Ir(III) complexes (Ir1-Ir5), featuring different electron-donating substituents to enhance the absorptivity, have been synthesized and studied as photosensitizers (PSs) for light-driven hydrogen production from water. Ir6-Ir7 were prepared as fundamental systems for comparisons. Electron donors, including 9-phenylcarbazole, triphenylamine, 4,4'-dimethoxytriphenylamine, 4,4'-di(N-hexylcarbazole)triphenylamine moieties were introduced on 6-(thiophen-2-yl)phenanthridine-based cyclometalating (C^N) ligands to explore the donor effect on the hydrogen evolution performance of these cationic Ir(III) complexes. Remarkably, Ir4 with 4,4'-dimethoxytriphenylamine achieved the highest turn-over number (TON) of 12 300 and initial turnover frequency (TOF ) of 394 h , with initial activity (activity ) of 547 000 μmol g h and initial apparent quantum yield (AQY ) of 9.59 %, under the illumination of blue light-emitting diodes (LEDs) for 105 hours, which demonstrated a stable three-component photocatalytic system with high efficiency. The TON (based on n(H )/n(PSr)) in this study is the highest value reported to date among the similar photocatalytic systems using Ir(III) complexes with Pt nanoparticles as catalyst. The great potential of using triphenylamine-based Ir(III) PSs in boosting photocatalytic performance has also been shown.
常见铱（III）配合物（例如，以苯基吡啶为配体）的弱光吸收特性阻碍了它们作为高效光敏剂在光催化水制氢中的应用。为了解决这一问题，已合成了一系列具有不同供电子取代基以增强吸光性的环金属化铱（III）配合物（Ir1-Ir5），并将其作为光驱动水制氢的光敏剂（PSs）进行研究。制备了Ir6-Ir7作为比较的基础体系。在基于6-（噻吩-2-基）菲啶的环金属化（C^N）配体上引入了包括9-苯基咔唑、三苯胺、4,4'-二甲氧基三苯胺、4,4'-二（N-己基咔唑）三苯胺部分在内的电子供体，以探究供体对这些阳离子铱（III）配合物析氢性能的影响。值得注意的是，含有4,4'-二甲氧基三苯胺的Ir4在蓝色发光二极管（LED）照射105小时的条件下，实现了最高的周转数（TON）为12300和初始周转频率（TOF）为394 h⁻¹，初始活性（activity₀）为547000 μmol g⁻¹ h⁻¹，初始表观量子产率（AQY₀）为9.59%，这证明了其为一个高效稳定的三元光催化体系。本研究中的TON（基于n(H₂)/n(PS₀)）是迄今为止在使用铱（III）配合物与铂纳米颗粒作为催化剂的类似光催化体系中报道的最高值。使用基于三苯胺的铱（III）PSs在提高光催化性能方面的巨大潜力也已得到展现。
