Enhanced durability of cyclometalated Ir(III) photosensitizer through intramolecular p-p interaction for robust photocatalytic hydrogen evolution

Developing photosensitizers with high durability is desirable to boost the practical application of photocatalytic hydrogen evolution. Herein, referring to the successful strategy in the field of light-emitting electrochemical cells, the reported Ir(III) complex with intramolecular p -p interaction, Ir2, is used as a photosensitizer to explore its durability. Photocatalytic hydrogen evolution experiment exhibits that the durability of Ir2 is significantly improved with the duration of 39 h, which is three times longer than that of the classical Ir(III) complex Ir1 (ca. 13 h) under the same condition. As revealed by theoretical calculation, the incorporation of intramolecular p-p interaction inhibits the rupture of metal-ligand bond in the excited state, thereby reducing the possibility of complex degradation. This is a novel approach to achieve a durable Ir(III) photosensitizer, which stimulates new molecular engineering endeavors. The finding proves the applicability of molecular design strategy in the field of light-emitting electrochemical cells to the photocatalytic hydrogen evolution system, thus boosting the cross integration of different disciplines.