Manganese (II,III) Oxide-Activated Carbon Black Supported PtRu Nanoparticles for Methanol Electrooxidation in Acid Medium

Abstract

In this work, PtRu nanoparticles supported on hybrid manganese (II,III)-carbon composites were prepared by a microwave-assisted polyol process in ethylene glycol. The obtained PtRu/(100-x) C.xMn 3 O 4 catalysts were characterized by XRD diffraction, TEM, SEM-EDX analysis, ICP-AES and electrochemical techniques. Small and well-distributed nanoparticles of about 2.6 nm were obtained over the hybrid support. The as-prepared catalysts presented similar Pt : Ru atomic ratio (ca. 3.4 : 1), indicating that the composition of the bimetallic system is unaffected by the oxide content in the hybrid support. However, the noble metal loading increased with the increase in the oxide content due to the formation of more nucleation sites during microwave heating. The electrochemical experiments showed that the best performance and the lowest poisoning rate are obtained with PtRu/90C.10Mn 3 O 4 followed by PtRu/70C.30Mn 3 O 4 . The bimetallic catalyst supported over 90C.10Mn 3 O 4 exhibited a steady current density of 215 mA mg PtRu −1 at 0.5 V, which is 40 % higher than that of PtRu/C. This behavior is mainly associated with the ability of Mn 3 O 4 to provide a large extra amount of hydroxyl groups and promote the dehydrogenation of methanol.