Sulfated zirconium oxide as electrode and electrolyte additive for direct methanol fuel cell applications

•Sulfated zirconium oxide (S-ZrO2) is used as electrode and electrolyte additive for direct methanol fuel cells (DMFCs).•Composite electrocatalysts based on Pt/C and S-ZrO2 display improved methanol tolerance and ORR activity than bare Pt/C.•S-ZrO2 as both catalyst and Nafion additive ensures an enhanced membrane/electrode interface stability.•Superior DMFC performance of the composite membrane electrode assembly in terms of current and power density.

Sulfated zirconium oxide (S-ZrO2) was used as electrode and electrolyte additive for direct methanol fuel cells (DMFCs). Composite Nafion electrolyte membranes and Pt electrocatalysts, both containing S-ZrO2 at different content, were prepared. The morphology and catalytic activity of prepared catalysts were investigated by scanning electron microscopy, and voltammetric technique. Results indicated that Pt/S-ZrO2 catalysts showed enhanced efficiency towards oxygen reduction reaction and increased methanol tolerance as compared to bare platinum. Pt/S-ZrO2-based carbon cloth electrodes were prepared and assembled as cathode in a DMFC, with Nafion/S-ZrO2 as composite electrolyte membrane. With respect to bare platinum and Nafion, higher values of current and power density were recorded at 110 °C. The use of S-ZrO2 both as catalyst and electrolyte additive provided enhanced membrane/electrode interface stability, as revealed by EIS spectra recorded during cell operation.