Visible-light-driven hydrogen (H2) production from water is a promising strategy to convert and store solar energy as chemical energy. Covalent organic frameworks (COFs) are front runners among different classes of organic photocatalysts. The photocatalytic activity of COFs depends on numerous factors such as the electronic band gap, crystallinity, surface area, exciton migration, stability of transient species, charge separation and transport, etc. However, it is challenging to fine tune all of these factors simultaneously to enhance the photocatalytic activity. Hence, in this report, an effort has been made to understand the interplay of these factors and identify the key factors for efficient photocatalytic H2 production through a structure-property-activity relationship. Careful molecular engineering allowed us to optimize all of the above plausible factors impacting the overall catalytic activities of a series of isoreticular COFs. The present study determines three prime factors: light absorption, charge carrier generation, and its transport, which influence the photocatalytic H2 production of COFs to a much greater extent than the other factors.
Bibliographical noteFunding Information:
This work was partly supported by a Grant-in-Aid for Scientific Research (no. 26102011, 15K21721, 17H06439, 19F19044, and 18H03918) from the Japan Society for the Promotion of Science (JSPS). M.S., A.K., I.B, and T.H. thank the high-performance computing center, ZIH Dresden, for computer time and recourses and Deutsche Forschungsgemeinschaft for financial support (SPP 1928, HE 3543/31-1). It is our pleasure to thank Prof. Koichi Eguchi for allowing T.K. to perform the nitrogen sorption isotherm. We thank Prof. Hiroki Kurata and Mr. Tsutomu Kiyomura for HR-TEM analysis. Dr. Y. Tsutsui, Dr. T. Sakurai, and Dr. W. Masuda are acknowledged for fruitful discussions.
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry