Iron–nitrogen-functionalized carbon as efficient oxygen reduction reaction electrocatalyst in microbial fuel cells

Iron phthalocyanine (FePc) was supported on carbon nanotubes (CNT) and black pearls (BP). The carbon supports were modified by a two-step treatment with nitric acid and ammonia gas to facilitate catalyst dispersion and obtain effective ORR active sites. The treatment allowed introducing oxygen and nitrogen functionalities on the carbon surface while maintaining an extensively developed porous structure, as demonstrated by elemental analysis and BET measurements. Electrochemical activity of the electrocatalysts was assessed by cyclic voltammetry and rotating disk voltammetry experiments. The catalyst obtained by supporting Fe on CNT modified with ammonia gas (Fe-CNT(NH3)) displayed the highest catalytic activity towards ORR at neutral pH as a results of the highest density of pyridinic nitrogen on the sample surface, as indicated by Xray photoelectron spectroscopy (XPS). The applicability of Fe-based electrocatalysts as ORR cathodes of microbial fuel cells (MFCs) was demonstrated by assembling single chamber air-cathodes MFCs and comparing the performance with that a MFC equipped with a reference Pt/C cathode. © 2016 Hydrogen Energy Publications LL

Bimetallic PdCo and PdFe electrocatalysts for the electrochemical oxidation of formica acid

Pd, PdCo and PdFe catalysts were prepared by the impregnation method, using sodium borohydride (NaBH4) as the reducing agent and a commercial carbon material (Vulcan XC-72R) as support. The synthesized electrocatalysts were tested for the formic acid oxidation reaction (FAOR) in acid medium (H2SO4 0.5 M). The morphology, composition and particle size of the electrocatalysts were characterized by physicochemical techniques as X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The catalytic activity was evaluated by cyclic voltammetry (CV) and chronoamperometry techniques (CA)Catalizadores de Pd, PdFe y PdCo fueron preparados por el método de impregnación, usando borohidruro de sodio (NaBH4) como agente reductor y un material de carbono comercial, (Vulcan XC-72R) como soporte. Los electrocatalizadores sintetizados fueron probados para la reacción de oxidación de ácido fórmico (FAOR, por sus siglas en inglés) en medio ácido (H2SO4 0,5 M). La morfología, la composición y el tamaño de partícula de los electrocatalizadores se caracterizaron mediante técnicas físico-químicas como difracción de rayos X (XRD), microscopía electrónica de barrido con espectroscopia por energía dispersiva (SEM-EDS) y microscopia electrónica de transmisión (TEM). La actividad catalítica se evaluó mediante técnicas de voltamperometría cíclica (CV) y cronoamperometría (CA