Two new cyclometalated Ir(III) diimine complexes were used as photosensitizers for homogeneous hydrogen evolution reaction (HER). These complexes were characterized by electrochemistry, ultraviolet–visible absorption, time-resolved and steady-state photoluminescence spectroscopy as well as by theoretical methods. The metal–ligand-to-ligand charge transfer character of their lowest excited state was shown to be competent for efficient H2 photoproduction in the presence of [Co(dmgH)2(py)Cl] as the hydrogen evolution catalyst, triethanolamine as the sacrificial electron donor, and HBF4 as the proton source. Under optimized experimental conditions, both complexes displayed HER over a period of more than 90 h, with turnover numbers reaching up to 11,650, 10,600, and 174 molH2 molPS–1 under blue-, green-, and red-light irradiation, respectively. Both complexes showed higher stability and efficiency vs HER than most of the previously described systems of the same kind.
De Kreijger, S., Schott, O., Troian-Gautier, L., Cauët, E., Hanan, G. S., & Elias, B. (2022). Red Absorbing Cyclometalated Ir(III) Diimine Photosensitizers Competent for Hydrogen Photocatalysis. Inorganic Chemistry, 61(13), 5245-5254. https://doi.org/10.1021/acs.inorgchem.1c03727 (Original work published 2022)