Enhanced and durable electrocatalytic performance of thin layer PtRu bimetallic alloys on Pd-nanocubes for methanol oxidation reactions

Abstract

As a renewable and promising energy devices, direct methanol fuel cells (DMFCs) have attracted a wide range of interest in recent years. The design of electrocatalysts highly influences the performance of DMFCs systems. Herein, PtRu bimetallic alloy nanoparticles have been fabricated onto a Pd nanocube (NC) core material by a facile wet chemical co-precipitation method. Structural and morphological characterization of the catalyst was performed using X-ray photoelectron spectroscopy (XPS) analysis, energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning TEM (HAADF-STEM) elemental mapping and temperature programmed reduction (TPR). The presence of a single TPR peak strongly supported bimetallic Pt–Ru interactions and alloying. The electrocatalytic performance of the as-synthesized PtRu@Pd-NC catalyst for the methanol oxidation reaction (MOR) is studied in HClO₄ aqueous solution by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS), and it is compared with that of a PtRu/C (E-TEK) catalyst. The catalyst has shown the highest specific activity (ca. 11.44 mA cm⁻² at 0.70 V), a lower onset potential and enhanced durability for MOR, which is significantly higher than the commercial PtRu/C (E-TEK) catalyst and other reported Pt/Pd-based catalysts. The results attribute to mutual interactions of the core–shell material that enhance the chemisorption of methanol.