1,4-Hydroquinone is a Hydrogen Reservoir for Fuel Cells and Recyclable via Photocatalytic Water Splitting

Photocatalytic splitting of water was carried out in a two-phase system. Nanocrystalline titanium dioxide was used as photocatalyst and potassium hexacyanoferrate(III)/(II) as electron transporter. Generated hydrogen was chemically stored by use of a 1,4-benzoquinone/1,4-hydroquinone system, which was used as a recyclable fuel in a commercialised direct methanol fuel cell (DMFC). The electrical output of the cell was about half compared to methanol. The conversion process for water splitting and recombination in a fuel cell was monitored by UV-Vis spectroscopy and compared to a simulated spectrum. Products of side reactions, which lead to a decrease of the overall efficiency, were identified based on UV-Vis investigations. A proof of principle for the use of quinoide systems as a recyclable hydrogen storage system in a photocatalytic water splitting and fuel cell cyclic process was given.