Band Gap Modification of Oxide Nanowires for Solar Hydrogen Production

The photocatalytic production of hydrogen via water splitting is a subject of immense interest due to its possible applications for converting and storing the abundant sunlight energy as chemical energy. However, with the currently used materials, efficiency of this process has been less than 1%. Improvement in the device performance is limited by either chemical instability or poor light absorption properties of these materials. Transition metal oxides are chemically stable during gas evolution, but have high band gap which limits their use in the UV part of the solar spectrum. In this work, we performed post synthesis nitridation of oxide nanowire arrays to form a completely new nitrided phase which has a lower band gap. The photoelectrochemical properties of these nanowire electrodes were characterized by UV-Vis, impedance, and photocurrent spectroscopy. The results are discussed in terms of their water splitting efficiency.