Effect of metal centers of complexes bearing bipyridine ligand for electrochemical‐ and photochemical‐driven hydrogen evolution

Abstract

In this work, two complexes with bipyridine ligand, [Co (bpy)2(SCN)2] 1 and [Ni (bpy)2(SCN)2] 2 have been prepared and well determined by single crystal X‐crystallography, power X‐ray diffraction (XRD), IR spectra, and so forth. Both exhibit good catalytic activity for electrochemical‐ and photochemical driven‐hydrogen evolution. Complexes 1 and 2 can electro‐catalyze H2 evolution from a neutral buffer (pH 7.0) with a turnover frequency (TOF) of 699.6 and 1469 mol H2/mol catalyst/h at an overpotential (OP) of 837.6 mV, respectively. Under blue light (λ = 469 nm), together with CdS nanorods (CdS NRs) as a photosensitizer, and ascorbic acid as a sacrificial electron donor, complexes 1 and 2 also can photo‐catalyze H2 evolution from water. Under an optimal condition, the turnover numbers (TONs) reach 10,600 (complex 1) and 15,180 (complex 2) mol of H2 per mol of catalyst during 48‐h irradiation, respectively. The average apparent quantum yields (AQYs) of complex 1 and complex 2 are 15.07% and 22.7%, respectively. Electrochemical and photochemical investigations show that the nickel complex has a higher activity for hydrogen evolution than that of the cobalt complex. These results can provide a new insight into design and manufacture of new H2‐production catalyst.