Electro-catalytic Activity of Carbon Nanofibers Supported Palladium Nanoparticles for Direct Alcohol Fuel Cells in Alkaline Medium

Candle Soot as a Novel Support for Nickel Nanoparticles in the Electrocatalytic Ethanol Oxidation

The enhancement of carbon-supported components is a crucial factor in augmenting the interplay between carbon-supported and metal-active components in the utilization of catalysts for direct ethanol fuel cells (DEFCs). Here, we propose a strategy for designing a catalyst by modifying candle soot (CS) and loading nickel onto ordered carbon soot. The present study aimed to investigate the effect of the Ni nanoparticles content on the electrocatalytic performance of Ni-CS, ultimately leading to the identification of a maximum composition. The presence of an excessive quantity of nickel particles leads to a decrease in the number of active sites within the material, resulting in sluggishness of the electron transfer pathway. The electrocatalyst composed of nickel and carbon support, with a nickel content of 20 wt%, has demonstrated a noteworthy current activity of 18.43 mA/cm2, which is three times that of the electrocatalyst with a higher nickel content of 25 wt%. For example, the 20 wt% Ni-CS electrocatalytic activity was found to be good, and it was approximately four times higher than that of 20 wt% Ni-CB (nickel-carbon black). Moreover, the chronoamperometry (CA) test demonstrated a reduction in current activity of merely 65.80% for a 20 wt% Ni-CS electrocatalyst, indicating electrochemical stability. In addition, this demonstrates the great potential of candle soot with Ni nanoparticles to be used as a catalyst in practical applications.

Electro-Catalytic Properties of Palladium and Palladium Alloy Electro-Catalysts Supported on Carbon Nanofibers for Electro-Oxidation of Methanol and Ethanol in Alkaline Medium

Carbon nanofibers (CNFs) supported by Pd and Pd-Sn electro-catalysts were prepared by the chemical reduction method using ethylene glycol as the reducing agent. Their physicochemical characteristics were studied using high resolution-transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and Bruanaer-Emmett-Teller (BET) analysis. FTIR revealed that oxygen, hydroxyl, carboxylic and carbonyl functional groups facilitated the dispersion of Pd and Sn nanoparticles. The doping of Pd with Sn to generate PdSn alloy was also confirmed by XPS data. The amorphous nature of CNFs was confirmed by XRD patterns which exhibited the Pd diffraction peaks. When Sn was added to Pd/CNFs, the diffraction peaks moved to lower angles. HRTEM images revealed that the CNFs with cylindrical shape-like morphology and also Pd-Sn nanoparticles dispersed on carbon support. The catalytic activity and stability towards alcohol electro-oxidation in alkaline medium at room temperature was evaluated using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). The obtained Pd-Sn/CNFs electro-catalyst exhibited a better electro-catalytic activity than Pd/CNFs and Pd/C electro-catalysts for both methanol and ethanol oxidation. The improvement of the electrochemical performance was associated with the synergistic effect via the addition of Sn which modified the Pd atom arrangement, thereby promoting oxidation through a dehydrogenation pathway. Furthermore, SnO2 generates abundant OH species which helps with increasing the rate of the oxidative removal of carbon monoxide (CO) intermediates from Pd sites.

Facile synthesis of PdAg nanocatalysts on CeO2/C composite supports as high-performance catalysts toward alkaline ethanol electro-oxidation

PdAg nanocatalysts on CeO₂/C supports were prepared using a facile, environment-friendly method and exhibited superior performance for ethanol electro-oxidation.