Cobalt Schiff-base complexes for electrocatalytic hydrogen generation.

Two cobalt(iii) complexes containing inexpensive Schiff-base ligands have been found to be active for proton reduction at low overpotentials. The dinitro and tetranitro derivatized Schiff-base complexes show catalytic activity at -0.96 V and -1.1 V vs. Fc+/Fc, respectively, resulting in overpotentials of 120 mV and 280 mV. Foot-of-the-wave analysis is used to examine the kinetic properties of these complexes, yielding a theoretical TOFmax of up to 4100 s-1. Experimental TOFs of 7 s-1and 3 s-1 are observed. Catalytic Tafel plots are also presented in order to benchmark the relationship between turnover frequency and overpotential.

Hydrogen evolution catalyzed by a cobalt complex containing an asymmetric Schiff-base ligand.

A cobalt(iii) complex containing an asymmetric Schiff-base ligand has been found to be active for proton reduction. Catalysis occurs at -1.2 V vs. Fc(+)/Fc (0.56 V vs. NHE), resulting in an overpotential of 350 mV. Additionally, the complex is active with a turnover frequency of 420 s(-1). An enhancement in activity is observed upon addition of water.