Enhancement of electroactivity of platinum–tungsten trioxide nanocomposites with NaOH-treated carbon support toward methanol oxidation reaction

Highlights: • Pt–WO₃/C electrocatalysts for methanol oxidation reaction is synthesized. • WO₃ is derived from the hydrolyzation of WCl₆ in dimethylformamide solution. • NaOH-treated carbon black support promotes the electrocatalytic activity of Pt. • Superior electrocatalytic activity than commercial Pt/C and PtRu/C is achieved. - Abstract: Platinum–tungsten trioxide nanocomposite electrocatalysts on carbon black support (Pt–WO₃/C) are synthesized and their electrocatalytic performances toward methanol oxidation reaction (MOR) are investigated in this study. Tungsten trioxide, which derived from the hydrolysis of tungsten hexachloride (WCl₆) in dimethylformamide (DMF) solution, is firstly deposited onto pristine or NaOH-treated Vulcan XC-72 carbon black (C or C_s) support to obtain tungsten trioxide/carbon black (WO₃/C or WO₃/C_s) nanocomposites, and then Pt nanoparticles are decorated onto these nanocomposites by polyol method to obtain Pt–WO₃/C or Pt–WO₃/C_s electrocatalysts. XRD and TEM characterizations are performed to examine the WO₃ structures and the size distributions of the Pt nanoparticles. The effects of WO₃ loading, annealing temperature and the NaOH-treatment of carbon black support on MOR mass activity and CO-tolerance ability of the electrocatalysts are investigated. The electrocatalyst (PtW(0.08)C_s200) with the WO₃/C_s nanocomposite derived from a DMF solution containing 0.08 M WCl₆, using NaOH-treated XC-72 carbon black as the support and annealed at 200 °C, achieves the highest MOR activity among all the electrocatalysts synthesized in this study. The MOR performances of PtW(0.08)C_s200 is superior to that of the commercial E-TEK Pt(20 wt%)/C and E-TEK PtRu(20 wt%)/C electrocatalysts under the same test conditions.