Effect of Substrate and Pyrolysis Atmosphere of FeNx Materials on Electrocatalysis of the Oxygen Reduction Reaction

Autor(es)

do Rego, Ulisses Alves ^{[1, 2]} ; Sgarbi, Ricardo ^[1] ; Lopes, Thiago ^[3] ; dos Santos, Clenilton Costa ^[4] ; Tanaka, Auro A. ^[4] ; Ticianelli, Edson A. ^[1]

Afiliação do(s) autor(es)

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

^[2] Univ Fed Maranhao, BR-65940000 Grajau, MA - Brazil

^[3] Univ Sao Paulo, Res Ctr Gas Innovat, Escola Politecn, Ave Prof Mello Moraes 2231, BR-05508030 Sao Paulo, SP - Brazil

^[4] Univ Fed Maranhao, BR-65080040 Sao Luis, MA - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ELECTROCATALYSIS; v. 12, n. 5, p. 548-563, SEP 2021.
• Citações Web of Science: 0

Resumo

In this work, several PGM-free materials supported on three types of carbon blacks (Vulcan XC-72, Monarch-1000, and Ketjenblack EC-600JD) and pyrolysed on N-2 and NH3 atmosphere are investigated as catalysts for the oxygen reduction reaction (ORR) in acid and alkaline electrolytes. The synthesized materials are characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The electrochemical characterization shows that for all N-2- and NH3-treated catalysts, the ORR activity is higher in alkaline than acidic conditions, though in both cases, the main reaction product is water, thus evidencing a predominant occurrence of a 4-electron oxygen reduction mechanism. Further, a reasonable relationship is established between Fe-N-x coordination (pyridinic-N) and pyrrolic-N contents and the ORR activity of catalysts in acid media (FeNx supported on Monarch-1000). In alkaline conditions, the iron coordination with pyridinic-N, coupled to a high carbon surface area (Ketjenblack), enhances the ORR activity regardless of the pyrolysis atmosphere. Finally, the ORR performance in alkaline medium of the FeNx/Ketjenblack catalyst pyrolysed under N-2 atmosphere is essentially the same as that achieved for the benchmark catalyst (Pt/C), while the durability of the best catalysts evidence to be quite promising in both acidic and alkaline media, as shown by a standard accelerated stability test. (AU)

• Processo FAPESP: 19/22183-6 - Electrocatálise VI: aspectos fundamentais e aplicados em problemas emergentes e clássicos em conversão eletroquímica de energia
• Beneficiário: Edson Antonio Ticianelli
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 17/15304-6 - Eletrocatálise além da platina: desenvolvimento de eletrocatalisadores sustentáveis
• Beneficiário: Thiago Lopes
• Modalidade de apoio: Bolsas no Brasil - Jovens Pesquisadores
• Processo FAPESP: 14/22130-6 - Eletrocatálise além da platina: desenvolvimento de eletrocatalisadores sustentáveis
• Beneficiário: Thiago Lopes
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores