A highly stable polypyridyl-based cobalt catalyst for homo- and heterogeneous photocatalytic water reduction

Abstract

Synthesis, characterization and activity in homogeneous photocatalytic hydrogen production of a cobalt polypyridyl complex are reported. TONs up to 9000 H(2)/Co could be achieved. Immobilization of the complex on a swellable resin yielded a recyclable heterogeneous catalyst.

Photo-induced redox catalysis for proton reduction to hydrogen with homogeneous molecular systems using rhodium-based catalysts

“…Some of these homogeneous photocatalytic systems can operate very efficiently (in terms of number of catalytic cycles or turnover number (TON)) in organic or mixed aqueous-organic solvents. Those reaching a turnover number versus catalyst (TON Cat ) above 100 in fully aqueous solution were rare and limited to rhodium [36][37][38][39] and platinum [40] but, since two years, several examples with cobalt [41][42][43][44][45][46][47][48][49][50][51][52][53][54], iron [55][56][57][58] nickel [59] were reported. Developing H 2 -evolving photocatalytic systems functioning in pure water is essential for their coupling with water oxidation systems in photoelectrochemical water-splitting devices.…”

Enhanced photocatalytic hydrogen evolution by combining water soluble graphene with cobalt salts

“…Cobalt-based catalysts are particularly attractive catalysts that are easily obtained, environmentally benign and rely on earth-abundant elements [16]. Molecular cobalt catalysts [17], such as polypyridyl complexes [18–19], oxime complexes [20], have been proven to be efficient in the photocatalytic production of hydrogen, and the turnover number (TON) has become higher upon introducing more appropriate ligands. Besides, cobalt-based heterogeneous structures are also of interest [21–22].…”

Shaping and enforcing coordination spheres: probing the ability of tripodal ligands to favour trigonal prismatic geometry

“…The synthesis of L 1 and L 2 have recently been reported by 20 Alberto, 12,13 by the addition of the lithiated 6-bromo-2,2'-bipyridine to the appropriate ketone (2,2-dipyridylketone or 2-pyridine-6-(2,2'-bipyridyl)ketone). Alternatively, we have found these ligands may be synthesised via the bromo substituted tripodal ligands.…”

“…1) which demonstrated an ability to enforce a 50 predominantly TP co-ordination geometry upon metal ions with a strong octahedral preference. 11 More recently Alberto reported an alternative synthesis of the analogous tetra 12 -and pentadentate 13 tripodal ligands, mono(2,2'-bipyrid-6-yl)bis(pyrid-2-yl)methanol and bis(2,2'-bipyrid-6- 55 yl)mono(pyrid-2-yl)methanol (L 1 and L 2 respectively; Fig. 1) which when co-ordinated to Co II was shown to be an effective water reducing catalyst.…”