An ion exchange route to produce WO3 nanobars as Pt electrocatalyst promoter for oxygen reduction reaction

► WO3 nanobars (3 nm × 10 nm) is synthesized through ion exchange route. ► The long-chain of the ion exchange resin results in the bar shape of WO3. ► The shape of WO3 varies with the concentrations of WO3 precursor. ► WO3 nanobars give highly promotion effect on Pt/C electrocatalyst. ► Pt/WO3 has higher electrochemical stability than Pt/C.