Three-Dimensional Pinecone-like Binder-Free Pt-TiO₂ Nanorods on Ti Mesh Structures: Synthesis, Characterization and Electroactivity towards Ethanol Oxidation.

Abstract

We report here the synthesis of binderless and template-less three-dimensional (3D) pinecone-shaped Pt/TiO₂/Ti mesh structure. The TiO₂ hydrothermally synthesized onto Ti mesh is composed of a mixture of flower-like nanorods and vertically aligned bar-shaped structures, whereas Pt film grown by pulsed laser deposition displays a smooth surface. XRD analyses reveal an average crystallite size of 41.4 nm and 68.5 nm of the TiO₂ nanorods and Pt, respectively. In H₂SO₄ solution, the platinum oxide formation at the Pt/TiO₂/Ti mesh electrode is 180 mV more negative than that at the Pt/Ti mesh electrode, indicating that TiO₂ provides oxygeneous species at lower potentials, which will facilitate the removal of CO-like intermediates and accelerate an ethanol oxidation reaction (EOR). Indeed, the Pt/TiO₂/Ti mesh catalyst exhibits current activity of 1.19 mA towards an EOR at a remarkably superior rate of 4.4 times that of the Pt/Ti mesh electrode (0.27 mA). Moreover, the presence of TiO₂ as a support to Pt delivers a steady-state current of 2.1 mA, with an increment in durability of 6.6 times compared to Pt/Ti mesh (0.32 mA). Pt is chosen here as a benchmark catalyst and we believe that with catalysts that perform better than Pt, such 3D pinecone structures can be useful for a variety of catalytic or photoelectrochemical reactions.