PHOTOCATALYTIC SPLITTING OF WATER - INCREASE IN CONVERSION AND ENERGY-STORAGE EFFICIENCY

The yield of the photocatalytic splitting of water using tris-[1-(4-methoxyphenyl)-2-phenyl-1,2-ethylenodithiolenic-S,S']tungsten as a photocatalyst-catalyst increases by more than threefold on going from 20 to 70-degrees-C, and there is no indication that the effect levels off at this temperature. The intensity of light (within the error limits of our experiments) does not have an appreciable effect. The nature of the reversible electron acceptor also influences the energy storage efficiency, eg. 1,1-dibenzyl-4,4'-bipyridiniumdichloride gives an energy storage efficiency approximately 10% higher than methylviologen. The energy storage efficiency also depends on the presence of electron donors; if PhN is added, the energy storage efficiency increases by 20%. With ethylenediaminetetraacetic acid (EDTA) the results are even more spectacular; there is a twofold increase, but only initially. At longer times the system is unstable. Overall light energy storage efficiencies can be as high as 7%, and the expectations for further improvement are very good.