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

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.

Introducing oxophilic metal and interstitial hydrogen into Pd lattice to boost electrochemical performance of alkaline ethanol oxidation

The sluggish kinetics of ethanol oxidation reaction (EOR), poor C1 selectivity and susceptibility to toxicity of CO intermediates hinder the commercialization of direct ethanol fuel cells (DEFCs). In this paper,...

THE ROLE OF CYTOCHROME P450 ISOFORMS OF HEPATOCYTE ENDOPLASMIC RETICULUM IN ETHANOL METABOLISM

Background. Three metabolic pathways that can function simultaneously are known to be involved in ethanol oxidation in the liver: alcohol dehydrogenase pathway, microsomal ethanol-oxidizing system, and catalase pathway. Though the cytochrome P450-dependent microsomal ethanol-oxidizing system plays an insignificant role in metabolism of small amounts of ethanol, it is induced in case of ethanol excess and becomes essential when ethanol is abused. The main components of this system are cytochrome P450 (CYP) isoforms of smooth endoplasmic reticulum. Objective. To characterize the role of the key isoforms of cytochrome P450 in ethanol oxidation. Material and methods. We carried out an analysis of modern literature data on the role of the main isoforms of cytochrome P450 in liver metabolism of ethanol. Results. Data on the primary role of cytochrome CYP2E1 in ethanol metabolism, as well as on the contribution of isoforms CYP1A2, CYP2B1/2, CYP2C, CYP3A4, CYP4B1 to ethanol oxidation are presented. Conclusions. Ethanol is metabolized by many CYPs of endoplasmic reticulum of hepatocytes. The importance of CYP in biotransformation processes in the liver necessitates the study of the role of individual CYP isoforms in ethanol metabolism for predicting changes in the pharmacokinetics of drugs and metabolism of endogenous compounds under the influence of ethanol.