Ultrahigh methanol electro-oxidation activity from gas phase synthesized palladium nanoparticles optimized with three-dimensional carbon nanostructured supports

The effect on the electrocatalytic activity of the chemical interaction of selenium with palladium centers: oxygen reduction and methanol oxidation reactions in alkaline medium

The chemical reactivity of two different selenium precursors (SeO₂and Se) with nanoparticulated palladium was studied in a simple aqueous phase synthesis to generate palladium selenides (Pd_xSe_y). As confirmed by XRD, XPS, TEM and energy dispersive spectroscopy analyses, the products generated showed different degrees of selenization according to the nature of the chemical precursor. Such degree of selenization was more important with elemental selenium, in contrast to SeO₂. Surface electrochemistry and CO stripping in alkaline medium, clearly revealed the different interactions and stability of Pd_xSe_yachieved with the Pd/C precursor depending on the selenium source. The electrocatalysis of the oxygen reduction reaction was also influenced by the Se source, first in the different degree of reactivity, and second in the selectivity of the reduction product between H₂O and H₂O₂, as well as the tolerance to the methanol oxidation reaction.

Metal-Based Electrocatalysts for Methanol Electro-Oxidation: Progress, Opportunities, and Challenges

Direct methanol fuel cells (DMFCs) are among the most promising portable power supplies because of their unique advantages, including high energy density/mobility of liquid fuels, low working temperature, and low emission of pollutants. Various metal-based anode catalysts have been extensively studied and utilized for the essential methanol oxidation reaction (MOR) due to their superior electrocatalytic performance. At present, especially with the rapid advance of nanotechnology, enormous efforts have been exerted to further enhance the catalytic performance and minimize the use of precious metals. Constructing multicomponent metal-based nanocatalysts with precisely designed structures can achieve this goal by providing highly tunable compositional and structural characteristics, which is promising for the modification and optimization of their related electrochemical properties. The recent advances of metal-based electrocatalytic materials with rationally designed nanostructures and chemistries for MOR in DMFCs are highlighted and summarized herein. The effects of the well-defined nanoarchitectures on the improved electrochemical properties of the catalysts are illustrated. Finally, conclusive perspectives are provided on the opportunities and challenges for further refining the nanostructure of metal-based catalysts and improving electrocatalytic performance, as well as the commercial viability.