Synthesis and Characterization of Nanostructured Pd−Mo Electrocatalysts for Oxygen Reduction Reaction in Fuel Cells

Abstract

Carbon-supported Pd 100-x Mo x (0 e x e 40) nanoparticles have been synthesized by a simultaneous thermal decomposition of palladium acetylacetonate and molybdenum carbonyl in an organic solvent (o-xylene) in the presence of Vulcan XC-72R carbon, followed by heat treatment up to 900 °C in H 2 atmosphere and characterized chemically and structurally. X-ray diffraction data reveal the formation of single-phase facecentered cubic solid solutions for 0 e x e 30 after heat treating at 900 °C and the occurrence of a Mo 2 C impurity phase for x ) 40. The particle size of the Pd 100-x Mo x samples increase with increasing heat treatment temperature as revealed by transmission electron microscopy. Cyclic voltammetry (CV) and rotating disk electrode (RDE) measurements reveal that the alloying of Pd with Mo enhances the catalytic activity for the oxygen reduction reaction (ORR) as well as the stability (durability) of the electrocatalyst. However, the activity reaches a maximum at Pd 90 Mo 10 and then decreases with increasing Mo content. Similar observations are made in both single-cell proton-exchange membrane fuel cell (PEMFC) and direct methanol fuel cell (DMFC) for the ORR activity. Interestingly, the 900 °C Pd 90 Mo 10 exhibits catalytic activity for ORR in DMFC at 80 °C similar to that of as-synthesized Pt despite a significantly larger particle size due to a high tolerance of Pd 90 Mo 10 to methanol poisoning.

Rapid Microwave‐Assisted Solvothermal Synthesis of Methanol Tolerant Pt–Pd–Co Nanoalloy Electrocatalysts

“…Recently, Pd-based alloys have drawn much attention as they exhibit promising activity for ORR [17][18][19][20]. However, Pt-Pd bimetallic alloys have not been explored extensively.…”

Electrocatalysts and Catalyst Layers for Oxygen Reduction Reaction

“…At first, the metal precursor and carbon support were mixed together and refluxed and finally dried, followed by a heat treatment up to 900 C in H 2 atmosphere. 82 …”

1D Pd-Based Nanomaterials as Efficient Electrocatalysts for Fuel Cells

“…Specifically, the Pd 9 Au and Pd 4 Pt nanowires possess ORR activities of 0.49 and 0.79 mA cm -2 , which are larger than the analogous value from commercial Pt nanoparticles (0.21 mA cm -2 ). Recent studies have demonstrated that Pd catalysts can produce high ORR activity when combined with appropriate transition metals, such as Co, Fe, Mo, etc [59,61,98]. By an organic phase reaction of [Pd(acac) 2 ] and thermal decomposition of [Fe(CO) 5 ] in a mixture of oleyamine and octadecene at 160°C, Li et al [73] synthesized PdFe nanorods (PdFe-NRs) with tunable length.…”