Willner Benjamin J, Aitchison Catherine M, Podjaski Filip, Lu Wanpeng, Tian Junfu, Durrant James R, McCulloch Iain
Department of Chemistry, Chemistry Research Laboratory, Oxford University, 12 Mansfield Road, Oxford OX1 3TA, U.K.
Department of Chemistry and Centre for Processable Electronics, Imperial College London, 80 Wood Lane, London W12 0BZ, U.K.
J Am Chem Soc. 2024 Nov 13;146(45):30813-30823. doi: 10.1021/jacs.4c08549. Epub 2024 Oct 30.
Increasing the interface area between organic semiconductor photocatalysts and electrolyte by fabricating nanoparticles has proven to be an effective strategy to increase photocatalytic hydrogen production activity. However, it remains unclear if increasing the interface by the introduction of porosity has as clear benefits for activity. To better inform future photocatalyst design, a series of polymers of intrinsic microporosity (PIMs) with the same conjugated backbone were synthesized as a platform to independently modulate the variables of porosity and relative hydrophilicity through the use of hydrophilic alcohol moieties protected by silyl ether protecting groups. When tested in the presence of ascorbic acid and photodeposited Pt, a strong correlation between the porosity and photocatalytic activity was found, with the more wettable analogue of two polymers of almost the same surface area delivering 7.3 times greater activity, while controlling for other variables. Transient absorption spectroscopic (TAS) investigation showed efficient intrinsic charge generation within 10 ps in two of the porous polymers, even without the presence of ascorbic acid or Pt. Detectable hole polarons were found to be immediately extracted by added ascorbic acid, suggesting the generation of reactive charges at regions readily accessible to electrolyte in the porous structures. This study directs organic semiconductor photocatalysts design toward more hydrophilic functionality for addressing exciton and charge recombination bottlenecks and clearly demonstrates the advantages of wettable porosity as a design principle.
通过制备纳米颗粒来增加有机半导体光催化剂与电解质之间的界面面积，已被证明是提高光催化产氢活性的有效策略。然而，通过引入孔隙率来增加界面是否对活性有同样明显的益处仍不清楚。为了更好地指导未来的光催化剂设计，合成了一系列具有相同共轭主链的固有微孔聚合物（PIMs）作为平台，通过使用受硅醚保护基团保护的亲水性醇部分来独立调节孔隙率和相对亲水性变量。在抗坏血酸和光沉积铂存在的情况下进行测试时，发现孔隙率与光催化活性之间存在很强的相关性，在控制其他变量的同时，两种表面积几乎相同的聚合物中更易润湿的类似物的活性高出7.3倍。瞬态吸收光谱（TAS）研究表明，即使不存在抗坏血酸或铂，两种多孔聚合物在10皮秒内也能有效产生本征电荷。发现可检测到的空穴极化子会立即被添加的抗坏血酸提取，这表明在多孔结构中电解质易于到达的区域会产生活性电荷。这项研究将有机半导体光催化剂的设计导向更具亲水性的功能，以解决激子和电荷复合瓶颈，并清楚地证明了可润湿孔隙率作为一种设计原则的优势。
