Hierarchical TiO2/ZnO Nanostructure as Novel Non-precious Electrocatalyst for Ethanol Electrooxidation

Metal oxides have a higher chemical stability in comparison to metals, so they can be utilized as electrocatalysts if the activity could be enhanced. Besides the composition, the morphology of the nanostructures has a considerable impact on the electrocatalytic activity. In this work, zinc oxide nano branches-attached titanium dioxide nanofibers were investigated as an economic and stable catalyst for ethanol electrooxidation in the alkaline media. The introduced material has been synthesized by electrospinning process followed by hydrothermal technique. Briefly, electrospinning of colloidal solution consisting of titanium isopropoxide, poly(vinyl acetate) and zinc nanoparticles was performed to produce nanofibers embedding solid nanoparticles. In order to produce TiO2 nanofibers containing ZnO nanoparticles, the obtained electrospun nanofiber mats were calcined in air at 600 °C. The formed ZnO nanoparticles were exploited as seeds to outgrow ZnO branches around the TiO2 nanofibers using the hydrothermal technique at sub-critical water conditions in the presence of zinc nitrate and bis-hexamethylene triamine. The morphology of the final product, as well as the electrochemical measurements indicated that zinc nanoparticles content in the original electrospun nanofibers has a significant influence on the electrocatalytic activity as the best performance was observed with the nanofibers synthesized from electrospun solution containing 0.1 g Zn, and the corresponding current density was 37 mA/cm2. Overall, this study paves a way to titanium dioxide to be exploited to synthesize effective and stable metal oxide-based electrocatalysts.