Substituent Effect on Ligand-Centered Electrocatalytic Hydrogen Evolution of Phosphorus Corroles

There have been few reports on the substituent effect of main-group-element corrole complexes as ligand-centered homogeneous electrocatalysts for the hydrogen evolution reaction (HER). The key to comprehend the catalytic mechanism and develop efficient catalysts is the elucidation of the effects of electronic structure on the performance of energy-related small molecules. In this work, the "push-pull" electronic effect of the substituents on electrocatalytic HER of phosphorus corroles was investigated by using 5,10,15-tris(phenyl) corrole phosphorus (1P), 10-pentafluorophenyl-5,15-bis(phenyl) corrole phosphorus (2P), 10-phenyl-5,15-bis(pentafluorophenyl) corrole phosphorus (3P), 5,10,15-tris(pentafluorophenyl) corrole phosphorus (4P) complexes bearing hydroxyl axial ligands and different numbers of fluorine atoms on the meso-aryl substituents. The results revealed that the catalytic HER activity of phosphorus corroles decreased with the increasing of fluorine atom numbers, it follows in the order 1P>2P>3P>4P. Density functional theory (DFT) calculations show that the corrole 1P has the lowest free energy barrier in catalytic HER.