Activating PtRu with rare earth alloying for efficient electrocatalytic methanol oxidation reaction†

Abstract

The development of direct methanol fuel cells (DMFCs) is limited by the slow kinetics of anodic methanol oxidation (MOR), and Pt-based materials have been recognized as the most promising catalysts for MOR. Alloying Pt with other transition metals is an effective strategy for improving the catalytic performance of Pt-based catalysts. Rare earth (RE) metals are considered favorable elements for modulating catalytic activity owing to their unique electronic structures and electronegativity. In this work, a series of Pt–Ru–RE ternary alloys was synthesized via a potassium vapor reduction method, and the mass activity of the Pt_2.7Ru_0.3Sc alloy was observed to be 1.03 A mg_pt⁻¹, which is almost four times that of Pt₉Ru alloy (0.21 A mg_pt⁻¹) and more than twice that of Pt₃Sc alloy (0.42 A mg_pt⁻¹). Moreover, the Pt_2.7Ru_0.3Sc alloy exhibited superior stability that could be activated repeatedly. Experiments and theoretical calculations revealed that Sc regulates the electronic structure of the Pt_2.7Ru_0.3Sc alloy and promotes the d-band center of superficial Pt downward, weakening the Pt–CO binding strength. Additionally, Ru was favorable for *OH adsorption, which was beneficial for the removal of the poisonous intermediate (*CO), and the synergistic effects enhanced the activity and stability of Pt_2.7Ru_0.3Sc alloy catalyst for MOR.