HY (Y = halide or OH−) splitting is a fuel-forming reaction of sufficient energy density for large-scale solar storage, but the reaction relies on chemical transformations that are not understood at the most basic science level.
Writing in the November 2 issue of ACS' Inorganic Chemistry journal, an MIT researcher says he has developed the necessary chemistry which pertains to multielectron transfers that are proton-coupled and involve the activation of bonds in energy-poor substrates. This platform leads to discovery paths for new hydrohalic acid- and water-splitting catalysts. The latter water-splitting catalyst captures many of the functional elements of photosynthesis. In doing so, he says, a highly manufacturable and inexpensive method for solar PE storage has been discovered.
Here is a link to the ACS article: http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/ic901328v?cookieSet=1