Biomass-derived nanoporous carbons as electrocatalysts for oxygen reduction reaction

• Autor(a) principal: Fernandes, Diana M
• Data de Publicação: 2020
• Outros Autores: Mestre, Ana S., Martins, Angela, Nunes, Nelson, Carvalho, A. P., Freire, Cristina
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.21/12396
• topic: Agave sisalana; Acid-char; Chemical activation; Oxygen reduction reaction; Electrocatalysis; Fuel cells

Electrocatalysts (ECs) for the oxygen reduction reaction (ORR) are crucial in fuel cells and for this reason developing cost-effective metal-free ECs with high electrocatalytic activity and high-volume production remains a huge challenge. Herein, we report the application as ORR electrocatalysts of a series of high grade nanoporous carbons, prepared by chemical activation of acid-chars obtained from the H2SO4 digestion and polycondensation (acid-mediated carbonization) of a biomass residue (Agave sisalana). All the nanoporous carbons presented good ORR electrocatalytic activities in alkaline medium. The AC(1) carbon exhibited the most promising ORR performance with E-onset = 0.84 vs. RHE, j(L, 0.26 V, 1600 rpm) = -3.12 mA cm(-2) and n(O2) = 3.6 electrons. The Tafel slopes of all carbons varied between 47 mV dec(-1) (AC(3)) and 250 mV dec(-1) (AC(1)). Furthermore, the carbons revealed superior tolerance to methanol when compared with commercial Pt/C and a competitive long-term electrochemical stability, with current retentions of 75-85 % after 20,000 s. The results obtained in this work suggest a promising method based on sustainable and economical biomass residues towards the development and engineering of novel value-added biomass-derived carbons as effective metal-free electrocatalysts for alkaline fuel cells.