Platinum nano-flowers with controlled facet planted in titanium dioxide nanotube arrays bed and their high electro-catalytic activity

Abstract

To better platinum's (Pt’s) electro-catalytic activity for oxidizing methanol, nano-flowers structured Pt catalysts with controlled facet had been planted onto titanium dioxide nanotube array (TNA) bed via a pulse electrodepositing method in an acid electrolyte containing chloroplatinic acid (H2PtCl6). The facet of Pt nano-flowers can be tuned as (111) or (100) by adding sulfuric acid (H2SO4) or hydrochloric acid (HCl) respectively into the precursor. It has been discovered that the nano-flower structured Pt catalysts with (111) facet generates a current density peak of 243.16 mA·mg−1(~2 times that of Pt catalysts with (200) facets) for catalytic oxidizing methanol in electrolyte containing 1 M methanol and 0.5 M H2SO4. In addition, the concentration of sulfuric acid in electrolyte has an effect on electrode's morphology, its electro-catalytic capability and stability. The mechanism of sulfuric acid anion for bettering Pt’s electro-catalytic activity had been comparatively investigated by replacing H2SO4 as HCl in precursor.