PdxNby electrocatalysts for DEFC in alkaline medium: Stability, selectivity and mechanism for EOR. (1st March 2018)

• Record Type: Journal Article
• Authors: Souza, F. Moura; Nandenha, J.; Batista, B.L.; Oliveira, V.H.A.; Pinheiro, V.S.; Parreira, L.S.; Neto, A.O.; Santos, M.C.
• Is Part Of: International journal of hydrogen energy. Volume 43:Number 9(2018)
• Page Start: 4505
• Page End: 4516
• Publication Date: 2018-03-01
• Subjects: Direct ethanol fuel cell -- Ethanol oxidation reaction -- Palladium -- Niobium -- Sol-gel method -- Alkaline fuel cell; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2018.01.058
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Pdx Nby /C binary electrocatalysts supported on Vulcan carbon XC72 were prepared by the sol-gel method. The materials are characterized by transmission electron microscopy, X-ray diffraction analysis, inductively coupled plasma–mass spectrometry and contact angle measurements. The electrocatalytic activity for ethanol electrooxidation reaction was studied by cyclic voltammetry, chronoamperometry, Tafel slope and accelerated durability testing. The direct ethanol performance and the products after the experiments were studied by Fourier transform infrared spectroscopy. Pd1 Nb1 /C (50:50 wt%) shows superior activity for ethanol oxidation compared to the other electrocatalysts prepared in this work. All electrocatalysts containing Nb show the highest current exchange density. The Tafel slope results suggest that the Nb modified the Pd-electrocatalyst to obtain a reaction path with high selectivity with only a single determining step with low production of the intermediates for the ethanol oxidation reaction. The best performance is obtained using Pd1 Nb1 /C 18.11 mW cm −2 . The Pd1 Nb1 /C electrocatalyst displays the highest production of CO2 and the lowest production of acetaldehyde. Pd1 Nb1 /C shows the highest peak current density during 1000 cycles of the experiment and the lowest mass loss of Pd after the cycling test. We find that the Nb modifies the Pd electrocatalysts from the bifunctional mechanism and reduces the loss of Pd during the accelerated durability test. Highlights: Pd/C doped with Nb in ratio 1:1 (w/w) showed the best performance for DEFC. FTIR ex situ spectra indicated that Pd1 Nb1 /C displayed highest production of CO2 . Pd/C doped with Nb shows highest current exchange density in Tafel experiment. Pd:Nb anode electrocatalysts are promising for DEFC in alkaline medium.