This work reports on the synthesis and characterization of hybrid electrocatalysts based on Pt nanoparticles and ceria nanorods (CeO 2 NR) supported on Vulcan XC-72 carbon black (Pt x (CeO 2 NR) y C z ) and evaluation of their electrocatalytic activity towards the oxygen reduction reaction (ORR), aiming the application of 4-electrons process in direct ethanol fuel cells (DEFCs). The hybrid electrocatalysts are characterized by X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), contact angle measurements and X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MS), CO-stripping analysis and electrocatalytic activity for ORR studied by the rotating ring-disc electrode (RRDE) technique and single fuel cell experiments. The Pt x (CeO 2 NR) y C z hybrid electrocatalysts prove to be efficient for ORR in a 4-electron process, maintaining a high conversion rate of O 2 to H 2 O, even at reduced platinum (Pt) load. The electrocatalyst presents a notable an unusual behavior in single fuel cell experiments presenting slightly lower open circuit voltage than Pt based commercial electrocatalysts, containing Pt only, as well as improved current and power density. This is achieved at operating temperatures between 40°C and 70°C, making the material very promising for application in high efficiency low temperature fuel cells.[a] V.
Pd x Nb y /C binary electrocatalysts supported on Printex 6 L carbon black were prepared by using an adapted chemical reduction method with sodium borohydride. The electrocatalysts were characterized by using SEM, TEM, XRD, EDS, ICP-MS, water contact angle and Raman spectroscopy. The best performance for the alkaline direct glycerol fuel cell (ADGFC) was obtained by using Pd 1 Nb 1 /C, which yielded a maximum power density of 27 mW cm À 2 at 70°C. Residues of products formed from the glycerol oxidation were analyzed by using FT-Raman and high-performance liquid chromatography (HPLC).The Pd 1 Nb 1 /C electrocatalyst exhibited a more negative onset potential for the CO oxidation reaction and a higher conversion rate of glycerol to carbonate. We suggest that the higher hydrophilicity, higher degree of disorder, and bifunctional effects enhanced the electrocatalytic activity of Pd, as Nb facilitated the oxidation of adsorbed CO in Pd and increased the transfer rate of electron from Pd to carbon black support Therefore, Nb is a promising co-catalyst for Pd-based electrocatalysts for ADGFCs.
The Cover Feature illustrates an alkaline direct glycerol fuel cell in operation, and the graph alongside shows the percentage of Fourier‐transform Raman products obtained from fuel cell operation. More information can be found in the Article by F. M. Souza et al. on page 5396 in Issue 21, 2019 (DOI: 10.1002/celc.201901254).
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