Improved electrocatalytic activity and stability of PtPd/graphene nanoplates using sulfated zirconia for methanol electro-oxidation in DMFCs: An experimental and computational study

In this study, graphene nanoplates (GNPs) are coated with sulfated zirconia (S-ZrO₂) to enhance the proton conductivity of the support and improve the electrochemical activity and stability of the platinum-palladium (PtPd) catalyst. The carbon monoxide (CO) tolerance and electrocatalytic activity of the prepared PtPd/S-ZrO₂-GNP electrocatalyst are evaluated for the methanol oxidation reaction (MOR). The electrocatalyst shows a reduction in the CO oxidation peak voltage (0.71 V vs. 0.93 V for Pt/C). PtPd/S-ZrO₂-GNPs exhibit higher catalytic activity for MOR compared to Pt/ZrO₂-GNPs and Pt/C, with electrochemical surface area (ECSA) values of 87.24, 69.36, and 54.91 m²·g_pt⁻¹, respectively. This enhancement is attributed to Pt/Pd alloying, the high surface area of GNPs, and sulfated ZrO₂. Tafel slope analysis also indicates higher MOR activity for PtPd/S-ZrO₂-GNPs. First-principles computations reveal that the magnetic nature of PtPd, the increased cell volume of S-ZrO₂, and improved charge transfer efficiency are responsible for boosting the electrocatalytic activity of PtPd/S-ZrO₂-GNPs towards MOR.