HYDROGEN FROM WATER: PHOTOCATALYTIC SPLITTING OF WATER WITH VISIBLE LIGHT?

Introduction One of the Holy Grails of chemistry is to seek a photo-activated catalyst to split water into H2 and O2 using solar spectra. Significant effort has been undertaken by the scientific community to develop a catalyst that can catalytically split water using visible light with limited success. However, one exception may be the homogeneous catalyst, tris-[1-(4methoxyphenyl)-2-phenyl-1,2ethylenodithiolenic-S,S’]tungsten, reported by researchers at the University of Athens. A unique and highly desirable characteristic of the tris-dithiolene catalyst is its ability to form both hydrogen and oxygen from water without the need to add a consumable (sacrificial) donor. Water is reduced to hydrogen and oxidized to oxygen in a sequential pathway. The energy storage efficiencies of the trisdithiolenes have been reported to range between 7-11%, values approaching the economic break point for solar production of hydrogen. While much work has been reported on the stability and efficiency of the various derivatives and isomers of tris-dithiolenes, little is known about the important steps of the mechanism that leads to hydrogen and oxygen formation. To this end, the understanding of the mechanism for the gas formation will assist in the design of the next generation of PCC’s with the aim in increasing their efficiency.