Yao Liang, Rodríguez-Camargo Andrés, Xia Meng, Mücke David, Guntermann Roman, Liu Yongpeng, Grunenberg Lars, Jiménez-Solano Alberto, Emmerling Sebastian T, Duppel Viola, Sivula Kevin, Bein Thomas, Qi Haoyuan, Kaiser Ute, Grätzel Michael, Lotsch Bettina V
Nanochemistry Department, Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany.
Department of Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
J Am Chem Soc. 2022 Jun 15;144(23):10291-10300. doi: 10.1021/jacs.2c01433. Epub 2022 Jun 3.
As covalent organic frameworks (COFs) are coming of age, the lack of effective approaches to achieve crystalline and centimeter-scale-homogeneous COF films remains a significant bottleneck toward advancing the application of COFs in optoelectronic devices. Here, we present the synthesis of colloidal COF nanoplates, with lateral sizes of ∼200 nm and average heights of 35 nm, and their utilization as photocathodes for solar hydrogen evolution. The resulting COF nanoplate colloid exhibits a unimodal particle-size distribution and an exceptional colloidal stability without showing agglomeration after storage for 10 months and enables smooth, homogeneous, and thickness-tunable COF nanofilms via spin coating. Photoelectrodes comprising COF nanofilms were fabricated for photoelectrochemical (PEC) solar-to-hydrogen conversion. By rationally designing multicomponent photoelectrode architectures including a polymer donor/COF heterojunction and a hole-transport layer, charge recombination in COFs is mitigated, resulting in a significantly increased photocurrent density and an extremely positive onset potential for PEC hydrogen evolution (over +1 V against the reversible hydrogen electrode), among the best of classical semiconductor-based photocathodes. This work thus paves the way toward fabricating solution-processed large-scale COF nanofilms and heterojunction architectures and their use in solar-energy-conversion devices.
随着共价有机框架材料（COFs）逐渐成熟，缺乏实现结晶且厘米级均匀的COF薄膜的有效方法仍然是推进COFs在光电器件中应用的一个重大瓶颈。在此，我们展示了横向尺寸约为200 nm且平均高度为35 nm的胶体COF纳米片的合成及其作为光阴极用于太阳能制氢的应用。所得的COF纳米片胶体呈现单峰粒径分布且具有出色的胶体稳定性，储存10个月后未出现团聚现象，并能通过旋涂形成光滑、均匀且厚度可调的COF纳米薄膜。制备了包含COF纳米薄膜的光电极用于光电化学（PEC）太阳能制氢转换。通过合理设计包括聚合物给体/COF异质结和空穴传输层的多组分光电极结构，COFs中的电荷复合得到缓解，从而显著提高了光电流密度，并使PEC析氢的起始电位极为正向（相对于可逆氢电极超过 +1 V），在基于经典半导体的光阴极中表现优异。因此，这项工作为制备溶液处理的大规模COF纳米薄膜和异质结结构及其在太阳能转换器件中的应用铺平了道路。
