Carbon supported nano Pt–Mo alloy catalysts for oxygen reduction in magnesium–air batteries

Abstract

In this work, carbon supported platinum–molybdenum alloy catalysts (Pt–Mo/C) with different Pt : Mo atomic ratios were synthesized via an impregnation reduction method at room temperature in aqueous solution. Their oxygen reduction reaction (ORR) performances were evaluated in magnesium–air batteries. Structural characterizations revealed that Pt–Mo alloy nanoparticles having an average size of 5 nm formed and distributed homogeneously on a carbon support. Electrochemical measurements showed that Pt–Mo/C catalysts exhibited better catalytic activity than Pt/C since a Pt-rich surface formed on the Pt–Mo alloy particles and Pt 5d-band vacancies increased due to the partial substitution of Mo for Pt. Among the Pt–Mo/C catalysts, Pt–Mo/C (3 : 1) showed the best performance with a maximum ORR current density of 21.14 mA cm⁻² in O₂-saturated NaCl solution and a specific discharge capacity of 1311 mA h g⁻¹ in Mg–air batteries, which are 164.9% and 11.8% higher than those of the Pt/C catalyst synthesized by using the same method (7.98 mA cm⁻² and 1156 mA h g⁻¹).