Preliminary studies of the electrochemical performance of Pt/X@MoO3/C (X = Mo2C, MoO2, Mo0) catalysts for the anode of a DMFC: Influence of the Pt loading and Mo-phase

• Core-shell Mo-particles were tested as Pt catalyst support.
• CO and methanol oxidation reactions were studied.
• The influence of the Pt loading and Mo-phase in the core was investigated.
• Core-shell Mo-particles act only as promoter for both reactions.
• CO and methanol oxidation is enhanced by electronic effects and facile OH formation.

The present study is focused on the influence of Pt loading on the reactivity of catalysts prepared supporting the metal on novel core–shell molybdenum substrates. The electrocatalytic activity and stability of nine Pt/X@MoO3/C catalysts (where X denotes the nature of Mo-phases in the core of the core–shell Mo-particle: Mo2C, MoO2 and/or Mo0) with three Pt loading (5, 20 and 30 wt% Pt) were tested for carbon monoxide and methanol electro–oxidation reactions.For both reactions, Pt loading appears to be a key factor, obtaining the best performance for those catalysts with higher Pt content. Furthermore, it is observed that the nature of X@MoO3/C samples plays an important role as promoter for CO and methanol oxidation. MoO3-shell catalyzes and homogenizes the potentiodynamic responses, while the reduced Mo-phase in the core produces an electronic effect which determines the catalytic activity and stability during the electro-oxidation processes investigated.