An effective and durable interface structure design for oxygen reduction and methanol oxidation electrocatalyst

Abstract

In order to inhibit the corrosion of carbon support and agglomeration of Pt nanoparticles in conventional Pt/XC-72 catalyst, the conventional Pt/C catalyst was modified by in-situ deposition of amorphous tungsten carbide (WC) at the catalyst/support interface. The results show that proper amount of WC can improve the performance and durability of catalyst, and excessive addition of W element will combine with oxygen and transform into WO3, thus covering Pt nanoparticles and reducing the active site of catalyst. When W content is controlled at 20 wt%, the half-wave potential (E1/2) of oxygen reduction reaction (ORR) polarization curve of Pt-WC (20 wt% W, PWC20) catalyst is positively shifted by 31 mV compared with that of conventional Pt/XC-72 catalyst, and the mass activity and specific activity of catalyst are increased by about 2.0 times at 0.85 V. After 10,000 cycles of accelerated durability test (ADT), the electrochemical active area (ECSA) of PWC20 catalyst decreased by 21.7% and the E1/2 was negatively shifted by 22 mV, while the ECSA of conventional Pt/XC-72 catalyst decreased by 49.49% and E1/2 shifted by 42 mV negatively. The peak current density of methanol oxidation reaction (MOR) is 1.41 times higher than that of conventional Pt/XC-72, and the forward scanning potential of methanol oxidation shifts 36 mV negatively. After 1000 cycles of ADT, the forward peak current density decreased by 15.23%, while the conventional Pt/XC-72 decreased by 26.62%. The results of CO stripping voltammetry and X-ray photoelectron spectroscopy (XPS) analysis show that the modification of catalyst/support interface by WC significantly improves the anti-CO toxicity ability of conventional Pt/C. The synergistic effect between WC and Pt enhances the metal-support interaction. The durability of catalyst toward ORR and MOR was improved by the modification of catalyst/support interface, and the performance and durability of proton exchange membrane fuel cell (PEMFC) cathode catalyst layer were also improved.