The design of metal catalysts for the production of H2, a clean and renewable fuel, required understanding of the electronic and steric factors on catalytic properties such as overpotential and turnover frequency (TOF). Studies of Co catalysts for H2 evolution have shown that Co catalysts with higher redox potentials from structural modification display little change in overpotential for H2 evolution and require stronger acid for catalysis. Co catalysts with lower overpotentials from ligand modifications generally show decreased turnover frequency for H2 evolution. In order to explore the electronic and steric effects of ligand scaffold on the catalytic properties for H2 evolution by cobalt complex with a pentadentate ligand, N,N-bis(2-pyridinylmethyl)-2,2'-bipyridine-6-methanamine (DPA-Bpy), we replaced the pyridyls in DPA-Bpy with more electron-withdrawing isoquinoline groups. In contrast to what have been reported before, our study demonstrate that the higher redox potential of Co center, resulting from replacement of pyridyls with isoquinoline groups, leads to significant lower overpotential and higher TOF, as well as enhanced stability for electrocatalytic H2 production in neutral aqueous solution.

Electronic tuning of H2 production catalyzed by Co complexes with pentadentate ligands

249th National Meeting (2015)

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