Investigation of PdIr/C electrocatalysts as anode on the performance of direct ammonia fuel cell

Author(s)

Assumpcao, M. H. M. T. ^[1] ; da Silva, S. G. ^[1] ; De Souza, R. F. B. ^[1] ; Buzzo, G. S. ^[1] ; Spinace, E. V. ^[1] ; Santos, M. C. ^[2] ; Neto, A. O. ^[1] ; Silva, J. C. M. ^[1]

Affiliation

^[1] Inst Pesquisas Energet & Nucl, IPEN CNEN SP, BR-05508900 Sao Paulo - Brazil

^[2] Univ Fed ABC, Ctr Ciencias Nat & Humanas, Lab Eletroquim & Mat Nanoestruturados, BR-09210170 Santo Andre, SP - Brazil

• Document type: Journal article
• Source: Journal of Power Sources; v. 268, p. 129-136, DEC 5 2014.
• Web of Science Citations: 31

Abstract

This work investigates the ammonia electro-oxidation considering electrochemical and direct ammonia fuel cell (DAFC) experiments. The working electrodes/anodes are composed of Pd/C, PdIr/C (90:10, 70:30, 50:50, 30:70 and 10:90 atomic ratios) and Ir/C. Solutions of 1 mol L-1 NH4OH and 1 mol L-1 KOH were used for electrochemical experiments while 1.0, 3.0 and 5.0 mol L-1 NH4OH in 1.0 mol L-1 KOH were used in DAFC. X-ray diffraction analysis of PdIr/C electrocatalysts suggests the formation of PdIr alloy, while transmission electron micrographs show the average particle diameters between 4.6 and 6.2 nm. Electrochemical experiments indicate Pdlr/C 30:70 as the best electrocatalyst in accordance with DAFC. The maximum power densities obtained with PdIr/C 30:70 as anode using 5 mol L-1 NH4OH and 1 mol L-1 KOH at 40 degrees C are 60% and 30% higher than the ones obtained with Pd/C and Ir/C electrocatalysts, respectively. The enhanced synergic effect in this specific composition may be assigned to an optimal ratio of palladium sites that dehydrogenates ammonia at lower overpotential with the lower surface coverage of Nada on iridium. Furthermore, electronic effect between palladium and iridium might also contribute to the decrease of poisoning on catalyst surface by N-ads. (C) 2014 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 12/22731-4 - Electrocatalysts SUPPORTED IN DIFFERENT SUBSTRATES prepared by codeposition electrochemistry for direct liquid fuel cell (methanol , ethanol and formic acidic)
• Grantee: Guilherme Soares Buzzo
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 11/18246-0 - Preparation of PD binary and ternary electrocatalysts by borohydride reduction for alcohol electro-oxidation in alkaline medium
• Grantee: Almir Oliveira Neto
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/01577-0 - Development of materials and degradation studies of electrocatalysts and supports for alkaline fuel cell
• Grantee: Júlio César Martins da Silva
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 12/03516-5 - Oxides-C supported electrocatalysts for direct liquid fuel cell anodes
• Grantee: Rodrigo Fernando Brambilla de Souza
• Support Opportunities: Scholarships in Brazil - Post-Doctoral