PdAg/C Electrocatalysts Synthesized by Thermal Decomposition of Polymeric Precursors Improve Catalytic Activity for Ethanol Oxidation Reaction

Abstract

An efficient ethanol oxidation reaction (EOR) is required to enhance energy production in alcohol-based fuel cells. The use of bimetallic catalysts promises decreasing reliance on platinum group metal (PGM) electrocatalysts by minimizing the use of these expensive materials in the overall electrocatalyst composition. In this article, an alternative method of bimetallic electrocatalyst synthesis based on the use of polymeric precursors is explored. PdAg/C electrocatalysts were synthesized by thermal decomposition of polymeric precursors and used as the anode electrocatalyst for EOR. Different compositions, including pristine Pd/C and Ag/C, as well as bimetallic Pd80Ag20/C, and Pd60Ag40/C electrocatalysts, were evaluated. Synthesized catalysts were characterized, and electrochemical activity evaluated. X-ray diffraction showed a notable change at diffraction peak values for Pd80Ag20/C and Pd60Ag40/C electrocatalysts, suggesting alloying (solid solution) and smaller crystallite sizes for Pd60Ag40/C. In a thermogravimetric analysis, the electrocatalyst Pd60Ag40/C presented changes in the profile of the curves compared to the other electrocatalysts. In the cyclic voltammetry results for EOR in alkaline medium, Pd60Ag40/C presented a more negative onset potential, a higher current density at the oxidation peak, and a larger electrically active area. Chronoamperometry tests indicated a lower poisoning rate for Pd60Ag40/C, a fact also observed in the CO-stripping voltammetry analysis due to its low onset potential. As the best performing electrocatalyst, Pd60Ag40/C has a lower mass of Pd (a noble and expensive metal) in its composition. It can be inferred that this bimetallic composition can contribute to decreasing the amount of Pd required while increasing the fuel cell performance and expected life. PdAg-type electrocatalysts can provide an economically feasible alternative to pure PGM-electrocatalysts for use as the anode in EOR in fuel cells.

Studies on the Catalytic Properties of Palladium–Niobium Electrocatalysts Supported on Carbon Nano-onions toward Isopropanol and Ethanol Electro-oxidation in an Alkaline Medium

“…Following the results obtained in Table , adding Nb lowers the poisoning rate value, thus suggesting that Pd–Nb/CNOs exhibited the lowest poisoning rate. The addition of Nb to the Pd structure modified the electronic structure of Pd, thus reducing the poisoning of the active sites . These results closely agree with the CV results, where Pd–Nb/CNOs showed high mass activity (Figure and Table ).…”

Synthesis of Bimetallic Nanoparticles and Applications—An Updated Review

“…For example, synthesis of bimetallic titanium complexes M-Ti-O (M = nickel-Ni, Cobalt-Co, Manganese-Mn) from cobalt, manganese and nickel metal precursors by using the thermal decomposition method were reported in the literature [98]. In addition, the thermal decomposition method of synthesis has been used to synthesize Pd-Ir, [59], Co-Mn [99], Pd x Ni y [100], Ti/Ce-Sb-SnO 2 NFs and Pd-Ag/C bimetallic nanoparticles [101].…”

Síntesis de nanopartículas de PdACu soportadas sobre carbón para la oxidación de etanol y bio-alcohol

“…Se ha reportado que la actividad electrocatalítica de Pd hacia la reacción de oxidación del etanol (ROBE) en medio alcalino es mayor y más estable que la del Pt [18][19][20]. Sin embargo, la actividad del Pd para la oxidación del etanol debe ser mejorada con la adición de nuevos catalizadores que puedan mejorar las cinéticas de oxidación y reducir el envenenamiento del electrodo por especies intermedias; esto se puede lograr por medio de la combinación de metales tales como Ru, Sn, Ag, Au, Co, Ni, Fe, y Cu debido a que presentan alta actividad catalítica y estabilidad en comparación con sus correspondientes mono metálicos, además de tolerar envenenamiento en la oxidación de etanol en medio alcalino [21][22][23].…”