Core-shell TiO ₂/C nanofibers as supports for electrocatalytic and synergistic photoelectrocatalytic oxidation of methanol

Carbon-coated TiO ₂ 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 H ₂SO ₄ solutions with methanol by cyclic voltammetry and chronoamperometry. The TiO ₂ 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 TiO ₂ fibers, denoted as Pt-TiO ₂/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-TiO ₂/C compared with those of Pt-TiO ₂ and Pt-C (Vulcan XC-72), respectively. Furthermore, the Pt-TiO ₂/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-TiO ₂/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-TiO ₂/C is enhanced 2.5 times as that in the dark. In brief, the cooperation between Pt, carbon shell and TiO ₂ support promotes methanol oxidation on Pt-TiO ₂/C with and without UV illumination.