Inkjet Printing of Functionalized TiO2 Catalytic Layer for Water Oxidation Reaction

ABSTRACTOur investigations with silane-modified TiO2 have revealed a beneficial effect of functionalization on the photoelectrochemical performance on spin-coated electrodes. However, in order to produce large area photoelectrodes, a more scalable manufacturing technology is required. Inkjet printing can fulfil this role and furthermore allow a finer control over coating morphologies. In this work, inkjet-printed photoelectrodes were prepared with silane-functionalized TiO2 nanoparticles, and investigated as electrodes for photoactivated water splitting. The catalyst layers, having thickness around 700 nm, were printed on FTO-coated glass supports, from cellulose stabilized dispersions. For comparison, electrodes of similar thicknesses were also prepared by spin-coating. After removing the stabilizer at 300 °C under air atmosphere, the electrodes were characterized in photoelectrochemical cells containing 0.5 M H2SO4 as electrolyte and a platinum ring as counter electrode. Under simulated sunlight, the best photocurrent densities for the oxygen evolution reaction were obtained for the inkjet-printed electrodes prepared with functionalized particles (up to 0.26 mA cm-2 at 1.2 V against the standard hydrogen electrode (SHE), compared to 0.18 mA cm-2 for spin coated). Microscopy of the printed electrodes shows structurally homogenous coatings with evenly distributed roughness. Under continuous illumination at 0.7 V (SHE), the electrodes showed no significant drop in photocurrent within five hours.