The Power of Controlling the Catalytic Centers in Boosting the Photocatalytic Hydrogen Evolution Performance of 2D-COFs

Carolina Gimbert-Suriñach^a, Pau Sarró^a, David Reyes-Mesa^a, Albert Granados^a, Adelina Vallribera^a, Roser Pleixats^a

^aDepartment of Chemistry and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universitat Autònoma de Barcelona, Cerdanyola del Vallès, 08193 Barcelona, Spain

Proceedings of The Future of Hydrogen: Science, Applications and Energy Transition (H2Future25)

Production

Ibiza, Spain, 2025 May 5th - 7th

Organizers: Teresa Andreu, Bahareh Khezri and Jose Mata

Contributed talk, Pau Sarró, presentation 020
Publication date: 27th March 2025

Generation of hydrogen through water splitting using visible-light irradiation in a photoelectrochemical cell (PEC) configuration has been a well-known topic since the 1970’s. Initially, inorganic semiconductor materials such as TiO₂ were exploited[1,2] thanks to their suitable electronic configuration and stability under photochemical conditions. However, limitations in solar to hydrogen efficiency has hampered their implementation into high performing devices. On the other hand, organic semiconductors have more recently emerged as promising materials to be used in this field. Prominent examples of this family of semiconductors are 2D-covalent organic frameworks (COFs), which are reticular materials with high crystallinity and porosity.[3,4] They have been applied to photocatalysis including visible light-induced HER with great success.[5,6] One of the advantages of COF materials is their versatility to control chemical and electronic structure, allowing to rationally design better photocatalytic materials by enhancing solar light harvesting, charge separation, interaction with co-catalysts or dispersibility in water.[7-11]

In this work, we have developed a new catalytic system for the photogeneration of hydrogen, based on an enamine linked 2D-COF containing thiazolo[5,4-d]thiazole moieties together with isolated metallic co-catalysts and ascorbic acid as sacrificial electron donor (SED), which resulted in benchmarking values in terms of catalytic rate for hydrogen generation. The catalytic system offers significant advantages compared to the known strategies –which rely on the in-situ formation of the catalytic species–,since it allows to tune and change each component separately and study its effect independently of one another. In this line, we have used advanced spectroscopic techniques to ascertain key aspects of the charge transfer processes between the different components that allowed us to understand preferred mechanistic pathways and to push the photocatalysis performance to the limit.

References:

[1] Fujishima, A.; Honda, K. Electrochemical Photolysis of Water at a Semiconductor Electrode. Nature 1972, 238, 37–38.

[2] Chen, X.; Shen, S.; Guo, L.; Mao, S. S. Semiconductor-based Photocatalytic Hydrogen Generation. Chem. Rev. 2010, 110, 6503–6570.

[3] Côté, A. P.; Benin, A. I.; Ockwig, N. W.; O’Keeffe, M.; Matzger, A. J.; Yaghi, O. M. Porous, Crystalline, Covalent Organic Frameworks. Science 2005, 310, 1166–1170.

[4] Geng, K.; He, T.; Liu, R.; Dalapati, S.; Tan, K. T.; Li, Z.; Tao, S.; Gong, Y.; Jiang, Q.; Jiang, D. Covalent Organic Frameworks: Design, Synthesis, and Functions. Chem. Rev. 2020, 120, 8814–8933.

[5] Stegbauer, L.; Schwinghammer, K.; Lotsch, B. V. A Hydrazone-Based Covalent Organic Framework for Photocatalytic Hydrogen Production. Chem. Sci. 2014, 5, 2789-2793.

[6] Rodríguez-Camargo, A.; Endo, K.; Lotsch, B. V. Celebrating Ten Years of Covalent Organic Frameworks for Solar Energy Conversion: Past, Present and Future. Angew. Chem. Int. Ed. 2024, e202413096.

[7] Vyas, V. S.; Haase, F.; Stegbauer, L.; Savasci, G.; Podjaski, F.; Ochsenfeld, C.; Lotsch, B. V. A Tunable Azine Covalent Organic Framework Platform for Visible Light-Induced Hydrogen Generation. Nat. Commun. 2015, 6, 8508.

[8] Biswal, B. P.; Vignolo-González, H. A.; Banerjee, T.; Grunenberg, L.; Savasci, G.; Gottschling, K.; Nuss, J.; Ochsenfeld, C.; Lotsch, B. V. Sustained Solar H2 Evolution from a Thiazolo[5,4-d]thiazole-Bridged Covalent Organic Framework and Nickel-Thiolate Cluster in Water. J. Am. Chem. Soc. 2019, 141, 11082–11092.

[9] Ghosh, S.; Nakada, A.; Springer, M. A.; Kawaguchi, T.; Suzuki, K.; Kaji, H.; Baburin, I.; Kuc, A.; Heine, T.; Suzuki, H.; Abe, R.; Seki, S. Identification of Prime Factors to Maximize the Photocatalytic Hydrogen Evolution of Covalent Organic Frameworks. J. Am. Chem. Soc. 2020, 142, 9752–9762.

[10] Subramaniyan, S.; Xin, H.; Kim, F. S.; Murari, N. M.; Courtright, B. A. E.; Jenekhe, S. A. Thiazolothiazole Donor–Acceptor Conjugated Polymer Semiconductors for Photovoltaic Applications. Macromolecules 2014, 47, 4199–4209.

[11] Shen, R.; Li, X.; Qin, C.; Zhang, P.; Li, X. Efficient Photocatalytic Hydrogen Evolution by Modulating Excitonic Effects in Ni‐intercalated Covalent Organic Frameworks. Adv. Energy Mater. 2023, 13, 2203695.

Acknowledgements:

Grant PID2021-128496OB-I00 funded by MICIU/AEI/10.13039/501100011033/INVESTIGO contract 200076ID5 and Grant 2021SGR00064 funded by AGUAR-Generalitat de Catalunya

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