An integrated zeolite membrane/RuO2 photocatalyst system for hydrogen production from water

A zeolite Y membrane on a RuO2 containing alumina support for photochemical applications is described. Nanofingers of ruthenium oxide are assembled within the alumina support by thermal decomposition of ruthenium dodecacarbonyl followed by oxidation of the metal. Hydrogen evolution was monitored on the dark alumina side upon visible light illumination of a solution of sensitizer Ru(bpy)(3)(2+), electron acceptor N,N '-trimethylene-2,2 '-bipyridinium (DQ(2+)), and sacrificial electron donor EDTA on the zeolite side of the membrane. The zeolite was ion-exchanged with DQ(2+), and propylviologen sulfonate (PVS) was present in solution on the alumina side of the membrane. It is proposed that upon photoexcitation, DQ(+center dot) radical is formed in solution on the zeolite side, which can exchange charge with DQ(2+) in the zeolite. Charge diffusion via self-exchange of electrons within the DQ(2+)/zeolite leads to charge migration onto the zeolite/alumina interface of the membrane and electron donation to PVS. Hydrogen is produced by the reduction of water by the PVS radicals on the RuO2 catalysts. This study demonstrates an architecture for photoinitiated spatial separation of charge across an similar to 4 mu m thick microporous membrane, along with utilization of the charge to produce H-2 from water.