Nb as an influential element for increasing the CO tolerance of PEMFC catalysts

Autor(es)

Rocha, Thairo A. ^[1] ; Ibanhi, Felipe ^[1] ; Colmati, Flavio ^[2] ; Linares, Jose J. ^[3] ; Paganin, Valdecir A. ^[1] ; Gonzalez, Ernesto R. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Chem Sao Carlos, BR-13560970 Sao Paulo - Brazil

^[2] Univ Fed Goias, Inst Chem, BR-74001970 Goiania, Go - Brazil

^[3] Univ Brasilia, Inst Chem, BR-70910000 Brasilia, DF - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Applied Electrochemistry; v. 43, n. 8, p. 817-827, AUG 2013.
• Citações Web of Science: 13

Resumo

Platinum-niobium catalysts were prepared as candidates for CO tolerant anode catalysts for low and high temperature PEM fuel cells (PEMFCs). Three different compositions were prepared by the formic acid method, from platinum (hexachloroplatinic acid) and niobium (niobium chloride) precursors on Vulcan XC-72R carbon black. Deposition of the niobium was found to be quite difficult, and only a fraction of the desired composition was achieved. Mean particle sizes were all in the nanometric range, between 2 and 3 nm. Diffraction patterns display neither insertion of niobium within the crystalline structure of platinum, nor any crystalline phase associated to that material. Nevertheless, the presence of Nb displays a noticeable effect on the CO tolerance of the catalyst firstly revealed by a reduction of the CO stripping onset potential. Fuel cell results, operating with Nafion(A (R)) at low temperature (80 A degrees C) and H-2 + 100 ppm of CO as fuel, and with H3PO4-doped ABPBI, at high temperature (150 A degrees C) and H-2 + 20,000 ppm of CO, display an enhancement in the performance compared to pure platinum, so niobium may be an interesting material for increasing the tolerance to carbon monoxide in PEMFC. Finally, CO/O-2 polarisation curves display a decrease in the current density in the presence of Nb, confirming that the enhanced CO tolerance can be attributed to a strong electronic effect that weakens the Pt-CO adsorption strength. (AU)

• Processo FAPESP: 10/07108-3 - Desenvolvimento de estratégias para aumentar a eficiência da reação de oxidação de etanol pelo mecanismo de 12 elétrons, dando CO2 como produto, no contexto das células a combustível de etanol direto
• Beneficiário: José Joaquín Linares León
• Linha de fomento: Bolsas no Brasil - Pós-Doutorado