Photocatalytic water splitting is a growing field aimed at storing solar energy in the form of hydrogen. In order for this technology to find practical application, efficient photon harvesting antennas should be conceived. In addition, low recombination rates in electron transfer steps that follow light absorption are desired. These criteria ensure high cage escape yields and subsequently a large quantum yield of hydrogen production in this multi-electron transfer process. In this work, the rational investigation of a series of ruthenium(II) complexes is presented along with their photochemical and photophysical properties in pure water. Pump-probe transiant absorption spectroscopy was utilized on Ru(phen)32+ [phen = 1,10-phenanthroline], Ru(bpy)32+ [bpy= 2,2’-bipyridine], and Ru(BPS)34- [BPS = bathophenanthroline disulfonate] in a catalytic mixture containing ascorbate electron donor and cobalt(II) catalyst. The cage escape yield was found to be very sensitive to the type of ligand utilized and a clear correlation was obtained between the kinetic curves of hydrogen evolution and the data extracted from transition absorption. Our mechanistic data helps the development of new molecular systems for photocatalytic water splitting applications.

Rational design of ruthenium(II) chromophores: Towards efficient photocatalytic proton reduction

253rd National Meeting (2017)

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