Core–shell TiO2/C nanofibers as supports for electrocatalytic and synergistic photoelectrocatalytic oxidation of methanol

Abstract

Carbon-coated TiO₂ fibers were synthesized as core–shell structured supports for highly dispersed Pt nanoparticles. The catalyst samples were characterized by XRD, Raman, TGA, SEM, TEM and EDX. Performance of methanol oxidation was evaluated in aqueous H₂SO₄ solutions with methanol by cyclic voltammetry and chronoamperometry. The TiO₂ nanofibers were coated with carbon shells mostly between 5 and 10 nm in thickness. Platinum nanoparticles around 2 nm were evenly deposited onto the as-synthesized carbon-coated TiO₂ fibers, denoted as Pt–TiO₂/C. Electrochemical experiments showed that the peak current density of methanol oxidation in the forward scan was significantly increased by 7.3 and 2.5 times on Pt–TiO₂/C compared with those of Pt–TiO₂ and Pt–C (Vulcan XC-72), respectively. Furthermore, the Pt–TiO₂/C electro-catalyst exhibited a lower onset potential and slower current decay than Pt–C, suggesting higher catalytic activity and better stability. In photo-electrochemical experiments, the electro-catalytic and photo-catalytic properties of Pt–TiO₂/C have been synergistically coupled to boost the performance of methanol oxidation. Under UV irradiation, the total peak current density of methanol oxidation on Pt–TiO₂/C is enhanced 2.5 times as that in the dark. In brief, the cooperation between Pt, carbon shell and TiO₂ support promotes methanol oxidation on Pt–TiO₂/C with and without UV illumination.