Synthesis and Characterization of [Ni(H₂O)(7-P^Ph₂N^ArSO3)₂](NaBF₄) for Light-Driven Quantum Dot-Catalyst Hydrogen Evolution

Light-driven hydrogen generation from water is a route to carbon-neutral fuels. However, the integrated light absorbers and catalysts must be compatible and functional under the same conditions. A sulfate-functionalized complex, [Ni(H₂O)(7-P^Ph₂N^ArSO3)₂](NaBF₄), where P^Ph₂N^ArSO3 = 4-(3,6-diphenyl-1,3,6-azadiphosphepan-1-yl)benzenesulfonate), was synthesized and characterized. A solid-state structure from single-crystal X-ray crystallography is also reported. The electrocatalytic activity for hydrogen evolution of this complex in 7:3 H₂O:CH₃CN was characterized by cyclic voltammetry and controlled potential electrolysis, with a maximum observed rate of 83 s^-1. Density functional theory was used to characterize the favorable binding of the sulfate functionalities to cadmium sulfide quantum dots. Experimental assembly of these catalysts onto cadmium sulfide quantum dots was successful. Both fast electron transfer and light-driven pH-dependent hydrogen evolution were observed.