Electrocatalytic and Photocatalytic Hydrogen Production in Aqueous Solution by a Molecular Cobalt Complex

Abstract

Ein einkerniger Cobalt‐Komplex mit einem neuartigen fünfzähnigen Liganden (siehe Bild) katalysiert die Entwicklung von Wasserstoff in ausschließlich wässriger Lösung. Der Komplex könnte als Elektro‐ sowie als Photokatalysator zur effizienten Bildung von Wasserstoff verwendet werden.

Photocatalytic generation of hydrogen from water using a cobalt pentapyridine complex in combination with molecular and semiconductor nanowire photosensitizers

“…Compared to the reported n app values of 1-8 for a series of cobalt complexes at an overpotential of ca. 500 mV in pH 2.2 buffers, 33 which were measured at the same scan rate and rotation 35 rate as this present study, 1 exhibits better efficiency as a hydrogen evolution catalyst in neutral pH aqueous solution at approximately the same overpotential. Similar results were obtained in the 0.2 M NaClO 4 (Figs S5 and S6), indicating that phosphate does not play a special role in this system.…”

“…6a and during the first 10-h photolysis, chromophore decomposition is the primary reason for the cease of hydrogen evolution after 8-h illumination. 35 Importantly, control experiments without photosensitizer or ascorbic acid showed no H 2 generation, and in the absence of catalyst, only negligible hydrogen was detected 80 under the same conditions (Fig. 6a and Fig.…”

“…46 35 The cyclic voltammogram of 1-CH 3 CN in acetonitrile solution features two reversible redox processes at E 1/2 = 0.98 V and 0.64 V vs SHE, assigned to metal-based Co(III)/Co(II) and Co(II)/Co(I) couples, respectively, with another irreversible reduction peak at -1.57 V vs SHE (Fig. S2).…”

“…Similar results have been reported for other cobalt complexes with pentadentate ligands in aqueous medium. 35,48 The pH-dependence of the reduction feature is more complex and is a topic under current investigation. …”

“…Harnessing solar energy to synthesize sustainable chemical fuels is a promising solution to the emerging energy challenge. 15 An appealing approach to this ultimate goal is to drive chemical water splitting to hydrogen and oxygen using solar energy input, 6 since the generation and combustion of 35 hydrogen from water is carbon neutral and sunlight is a sustainable energy source. A key challenge for water splitting is developing catalysts for the direct and efficient production of hydrogen from protons.…”