A nickel pyridine-selenolate complex for the photocatalytic evolution of hydrogen from aqueous solutions

Abstract A nickel pyridine-selenolate complex, [Ni(4,4′-dmbpy)(2-pySe)2] (1, where 4,4′-dmbpy = 4,4'-dimethyl-2,2'-bipyridine, and 2-pySe = pyridine-2-selenolate), has been synthesized, and investigated for photocatalytic production of H2 from aqueous solution. Electrochemical studies showed that the nickel complex 1 can efficiently electrocatalyze H2 evolution from weakly acidic solutions. Under visible-light irradiation (λ > 420 nm), the complex 1 displays impressive H2 evolution activity with a TON of 1340 (based on a catalyst) in a noble-metal-free system, which contains fluorescein (Fl) as photosensitizer and triethylamine (TEA) as sacrificial electron donor in acetonitrile-water solution. It should be noted that complex 1 is the rare example of nickel pyridine-selenolate complex as photocatalyst for water reduction.