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Three cobalt triaryl corroles bearing an electron‐withdrawing or electron‐donating group at 10‐meso‐phenyl were synthesized and characterized. Two of them are new cobalt corroles prepared in this study. These cobalt corroles were characterized using high‐resolution mass spectrometry, UV–Vis., nuclear magnetic resonance, X‐ray photoelectron spectroscopy, and single‐crystal X‐ray structure determination. All synthesized cobalt corroles efficiently catalyzed the hydrogen evolution reaction (HER) in neutral aqueous media at an overpotential of 838 mV. The HER activity of these cobalt corroles significantly depended on the virtue of peripheral substituents. [ABSTRACT FROM AUTHOR]

Four free‐base corroles (F15C, F12C, F10C, F8C) and their cobalt(III) complexes were used as homogeneous electrocatalysts for hydrogen evolution using acetic acid, trifluoroacetic acid and water as proton sources. Free‐base corrole was firstly reported as electrocatalyst for H2 evolution. The results showed that free‐base corrole was active in electrocatalytic hydrogen evolution reaction (HER) in trifluoroacetic acid. And cobalt(III) corroles bearing hydroxyethyl amino groups were more efficient in HER as compared to their benchmark corroles. The catalytic active species of four tested cobalt(III) corroles were CoII‐H in acetic acid/dimethylformamide solvent. In water solution, both CoIII‐H and CoII‐H may be involved in HER. Interestingly, when trifluoroacetic acid was used as proton source, CoII‐H was the mainly active intermediate for F15CCo and F10CCo, and CoIII‐H for F12CCo and F8CCo, respectively. As for the free‐base corrole, (·Cor)H4 and [(·Cor)H3]– were the catalytic active species. [ABSTRACT FROM AUTHOR]

Catalytic activities for hydrogen (H2) evolution of cobalt 5,10,15-tris(phenyl)corrole (1) and 5,10,15-tris(4-nitrophenyl)corrole (2) (in homogeneous system was examined from acetic acid and water. In phosphate buffer solution (pH 7.0), the hydrogen evolution turnover frequency (TOF) for 1 and 2 were 62 and 150 h−1 at the overpotential of −1.53 V versus Ag/AgCl. In acetic acid media, hydrogen evolution TOF for 1 and 2 were 56 and 127 h−1, respectively, at an overpotential of 961 mV versus Ag/AgNO3. In the practical electrocatalytic hydrogen evolution experiment at −1.45 V (vs. Ag/AgCl) overpotential for 1 h, the TOF were 76 and 188 h−1 for 1 and 2, respectively. No observable decomposition of the catalyst could be observed after electrolysis for 72 h with a glassy carbon electrode. [ABSTRACT FROM AUTHOR]