Solar fuel production in a novel polymeric electrolyte membrane photoelectrochemical (PEM-PEC) cell with a web of titania nanotube arrays as photoanode and gaseous reactants

Abstract

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 nanotube arrays photoanode, a Pt/C cathode, a Pt/C reference electrode and a proton conducting polymeric electrolyte membrane (PEM), which serves both as compact reactor for water splitting and as gas separator. The design is inspired by PEM electrolysis technology and modified appropriately to allow light irradiation and to host a third electrode compartment, which enables the use of a hydrogen reference electrode. The titanium dioxide nanotube arrays (TNTAs) photoanodes were synthetized, 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 (i.e. PEM-PEC cell) and liquid media (conventional PEC cell). Due to the presence of the PEM-PEC reference electrode comparison of the results was possible. Gas phase operation with either He or air as carrier exhibits very promising photoefficiency in comparison with conventional PEC cells. Additionally the performance of our PEM-PEC cell was also investigated for simultaneous anodic air treatment and cathodic hydrogen evolution.