title: A hydrogen-evolving Ni(P2N2)2 electrocatalyst covalently attached to a glassy carbon electrode: preparation, characterization, and catalysis. comparisons with the homogeneous analogue.
abstract: A hydrogen-evolving homogeneous Ni(P2N2)2 electrocatalyst with peripheral ester groups has been covalently attached to a 1,2,3-triazolyllithium-terminated planar glassy carbon electrode surface. Coupling proceeds with both the Ni(0) and the Ni(II) complexes. X-ray photoemission spectra show excellent agreement between the Ni(0) coupling product and its parent complex, and voltammetry of the surface-confined system shows that a single species predominates with a surface density of 1.3 × 10(-10) mol cm(-2), approaching the value estimated for a densely packed monolayer. With the Ni(II) system, both photoemission and voltammetric data show speciation to unidentified products on coupling, and the surface density is 6.7 × 10(-11) mol cm(-2). The surface-confined Ni(0) complex is an electroctalyst for hydrogen evolution, showing the onset of catalytic current at the same potential as the soluble parent complex. Decomposition of the surface-confined species is observed in acidic acetonitrile. This is interpreted to reflect the lability of the Ni(II)-phosphine interaction and the basicity of the free phosphine and bears on concurrent efforts to implement surface-confined Ni(P2N2)2 complexes in electrochemical or photoelectrochemical devices.
authors: Center for Molecular Electrocatalysis, Physical Sciences Division, K2-57, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States.
authors: Atanu K
authors: AK
authors: Das
authors: Mark H
authors: MH
authors: Engelhard
authors: R Morris
authors: RM
authors: Bullock
authors: John A S
authors: JA
authors: Roberts