Porphyrin Small Molecules for Photocatalytic Hydrogen Evolution

Abstract

Recently, photocatalytic hydrogen evolution (PHE) has been intensively researched for producing H2 as a clean energy and renewable fuel. Over the last few decades, porphyrins and their derivatives have received immense interest for artificial photosynthesis which mimics the natural photosynthesis of plants. To apply porphyrins as photosensitizer in PHE, we first reported that the conjugation of naphthalimide (NI) chromophore to the Zn(II)-porphyrin ring enhanced the PHE of porphyrin photosensitizers.1 This is mainly because a Förster resonance energy transfer (FRET) from the NI energy donor to the porphyrin ring energy acceptor improves the light-harvesting property and stabilizes the photoexcited singlet states of porphyrin with a longer electron lifetime, and further facilitates an efficient photoinduced hole-electron separation and fast migration in the photocatalytic systems. Next, we further demonstrated that that NI-conjugated Pt(II)-porphyrins are capable of undergoing highly efficient cocatalyst-free PHE due to the FRET and the long-lived triplet excited states of Pt(II)-porphyrin. At the same time, the conjugation of Ir-complex onto Zn(II)-porphyrin through a phenyl linkage, leads to a synergistic effect of aggregation-induced emission (AIE), aggregation caused by quenching (ACQ) inhibition, and FRET.2 As a result, this complex exhibits highly efficient cocatalyst-free PHE because of efficient UV-visible light-harvesting, longer photoexcited electron lifetime, and thereby more efficient electron transfer from the photoexcited porphyrin to the proton for water reduction.


References

1. Bodedla, G. B.; Li, L. L.; Che, Y. Y.; Jiang, Y. J.; Huang, J.; Zhao, J. Z.; Zhu, X. J. Chem. Commun. 2018, 54 (82), 11614-11617.
2. Zheng, K. L.; Bodedla, G. B.; Hou, Y. Q.; Zhang, J.; Liang, R. H.; Zhao, J. Z.; Phillips, D. L.; Zhu, X. J. J. Mater. Chem. A 2022, 10 (8), 4440-4445.


Biography

Prof. Zhu Xunjin is currently a Associate Professor at the Department of Chemistry, Hong Kong Baptist University. Prof. Zhu obtained his PhD degree in 2006 at the Department of Chemistry, Hong Kong Baptist University, and worked as post-doctoral fellow from 2006 to 2010 at the University of Texas at Austin and Georgia Institute of Technology, next, started his academic career as Research Assistant Professor and Assistant Professor from 2010 to 2019 at the Department of Chemistry, Hong Kong Baptist University. His current research interests focus on the design and synthesis of porphyrin materials for various green technologies, ranging from organic solar cells, artificial photosynthesis, to electrocatalysis.