Catalytic performance of a square planar nickel complex for electrochemical- and photochemical-driven hydrogen evolution from water

A square planar nickel complex bearing salicylketoxime (SAO), Ni-SAO has been synthesized and well characterized by ESI-MS and single-crystal X-ray diffraction, etc. Ni-SAO exhibits good activity in both electrocatalytic and photocatalytic hydrogen evolution reaction (HER). Under an overpotential (OP) of 837.6 mV, Ni-SAO can electrocatalyze hydrogen evolution from a neutral aqueous buffer with a turnover frequency (TOF) of 1428 mol of hydrogen per mole of catalyst per hour (mol H2 /mol catalyst/h). Moreover, under blue light (lambda = 469 nm), a three-component system containing Ni-SAO as a catalyst, CdS nanorods (CdS NRs) as a photosensitizer, and ascorbic acid (H2A) as a sacrificial electron donor also can afford hydrogen with a turnover number (TON) of 8138 mol H2 per mol of catalyst (mol of cat-(1)) during 48 h irradiation. The highest apparent quantum yield (AQY) is about 16.5% at 469 nm.