Development of doped TiO₂ nanostructures for photo-electrochemical hydrogen generation
Gaye, Megan K.
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In situ generation of hydrogen in photo-electrocatalytic cells shows promise as a portable, efficient, and reliable energy source for expeditionary naval operations. Although several methods are currently used to generate hydrogen, photocatalytic watersplitting stands out due to its ability to provide hydrogen through solar energy conversion, a clean and renewable method. It is believed that the efficiency of the photocatalytic process could be greatly enhanced by doping the surface of the photoanodes with transition metals. This research aimed to generate TiO₂ nanoarrays doped with thin (5–30nm) layers of nickel for future application as the anode in photoelectrocatalytic cells (PEC). Nanoarrays were prepared using anodization in an electrolyte bath, which consisted of ammonium fluoride, ethylene glycol, and deionized water. The Ni-TiO₂ samples were annealed in air or inert atmospheres to produce crystalline structures. Ni-doped TiO₂ nanoarray surface morphology, composition, and microstructure were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and transmission electron microscopy. The annealed nanoarrays consisted of nickel (or nickel oxide) layers on top of a crystalline anatase array. The introduction of Ni/NiO decreased the reflectivity of TiO₂ arrays up to a 40%, and it is expected to significantly enhance the material’s photocatalytic activity.
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