Visible-light-driven photocatalytic system based on a nickel complex over CdS materials for hydrogen production from water

Abstract

Based on that the evolution of renewable H2 by using a photochemical method requires photoinduced electron transfer (ET) from a light harvester to an electrocatalyst in water, we present a nickel complex, [BzPyN(CH3)2]2[Ni(i-mnt)2] 1 (i-mnt2−=2,2-dicyanoethylene-1,1-dithiolate) that acts as both an electrocatalyst and a photocatalyst for H2 generation from water via an unstable nickel hydride intermediate. As an electrocatalyst, this nickel complex can catalyze hydrogen generation from a neutral buffer with a turnover frequency (TOF) of 577.4mol of hydrogen per mole of catalyst per hour (mol H2/mol catalyst/h) at an overpotential (OP) of 837.6mV. As a photocatalyst, combining with CdS nanorods (CdS NRs) as a photosensitizer, and ascorbic acid (H2A) as a sacrificial electron donor, it can photocatalyze hydrogen evolution in heterogeneous environments and can work for 100h. Under an optimal condition, the highest hydrogen evolution turnover number (TON) reaches 85820mol of H2 per mol of catalyst during 70h irradiation, and the highest apparent quantum yield (AQY) is ∼23% at 420nm. And possible cycles for H2 production by the electrocatalytic and photocatalytic systems are afforded.