A nickel complex of 2,2-dicyanoethylene-1,1-dithiolate, a catalyst for electrochemical and photochemical driven hydrogen evolution

Abstract

The reaction of NiCl2, K2(i-mnt) (i-mnt2−= 2,2-dicyanoethylene-1,1-dithiolate) and 1-benzyl-4-amino-pyridinium bromide [BzPyNH2]Br affords a nickel complex, [BzPyNH2]2[Ni(i-mnt)2], a molecular catalyst for electrochemical and photochemical driven hydrogen evolution. As an electrocatalyst, [BzPyNH2]2[Ni(i-mnt)2] can electrocatalyze hydrogen generation from a neutral buffer with a turnover frequency (TOF) of 556 (±3) mol of hydrogen per mole of catalyst per hour (mol H2/mol catalyst/h) at an overpotential (OP) of 837.6 mV. As a photocatalyst, combining with CdS nanorods (CdS NRs) as a photosensitizer, and ascorbic acid (H2A) as a sacrificial electron donor, [BzPyNH2]2[Ni(i-mnt)2] photocatalyzes hydrogen evolution in heterogeneous environments with a turnover number (TON) of 18420 (±5) mol H2 per mol of catalyst during 60 h irradiation. The highest apparent quantum yield (AQY) is ∼10% at 469 nm. Several chemical and physical methods are employed to understand catalytic procedures for H2 production.