Polymeric Electrolyte Membrane Photoelectrochemical (PEM-PEC) Cell with a Web of Titania Nanotube Arrays as Photoanode and Gaseous Reactants

A novel photoelectrochemical (PEC) cell design is proposed and investigated for H2 production with gaseous reactants. The core of the cell is a membrane electrode assembly (MEA) that consists of a TiO2 photoanode of nanotube arrays, a Pt/C counter and reference electrodes and a polymeric electrolyte membrane (PEM) with proton conductivity, which serves both as compact reactor for water splitting and as gas separator. The design was inspired by PEM electrolysis technology and modified appropriately for allowing illumination and it is also equipped with a third compartment which enables the use of a hydrogen reference electrode. Photoanodes of titania nanotube arrays, TNTAs, were developed, for the first time, on a Ti-web of microfiber substrates, by electrochemical anodization. The performance of TNTAs/Ti-web photoanodes were evaluated in both gaseous and liquid reactants. Due to the presence of reliable reference electrode in gas phase direct comparison of the results was possible. Gas phase operation with He or Air as carrier gases and only 2.5% of water content exhibits very promising photoefficiency in comparison with conventional PEC cells.