Porous carbonaceous materials simultaneously dispersing N, Fe and Co as bifunctional catalysts for the ORR and OER: electrochemical performance in a prototype of a Zn-air battery

• Published in: Dalton transactions : an international journal of inorganic chemistry 2024-02, Vol.53 (7), p.3143-3158
• Main Authors: Jaramillo, Daniela, Alvarez, German, Díaz, Cristian, Pérez, Sebastián, Muñoz Saldaña, Juan, Sierra, Ligia, López, Betty Lucy, Moreno-Zuria, Alonso, Mohamedi, Mohamed, Palacio, Ruben
• Format: Article
• Language: English
• Subjects: Bimetals; Carbonaceous materials; Catalysts; Cobalt; Composition; Cycles; Dispersion; Electrocatalysts; Electrochemical analysis; Iron; Metal air batteries; Nitrogen; Open circuit voltage; Porous materials; Prototypes; Silicon dioxide; Zinc-oxygen batteries
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d3dt03330a

Infiltration of the mesoporous structure of SBA-15 silica as a hard template with phenanthroline complexes of Fe 3+ and Co 2+ allowed the simultaneous dispersion of nitrogen, iron and cobalt species on the surface of the obtained carbonaceous CMK-3 silica replica, with potential as bifunctional heterogeneous catalysts for the cathodic oxygen reduction and evolution reactions (ORR and OER). The textural properties and mesopore structure depended on the composition of the material. The carbonaceous FeCoNCMK-3 (1/1), obtained with an Fe/Co molar ratio of 1/1, exhibited an ordered cylindrical mesoporous structure with a high mesopore volume, a rather homogeneous composition in terms of total and surface concentrations of iron and cobalt, and a balanced presence of pyridinic-, pyrrolic- and graphitic-N species. FeCoNCMK-3 (1/1) could improve the ORR kinetics by adsorption and reduction of O 2 through the 4-electron mechanism with a current density of −17.37 mA cm −2 , E onset of 1.13 V vs. RHE and E 1/2 of 0.75 V when compared to metal-free, monometallic or bimetallic electrocatalysts with a higher amount of cobalt than that of iron. In addition, FeCoNCMK-3 (1/1) exhibited activity for the OER, presenting lower values of E onset (1.52 V), E j 10 (1.78 V) and the Tafel slope (76.3 mV dec −1 ) with respect to other catalysts. When evaluated as a cathode in a prototype of a Zn-air battery, FeCoNCMK-3 (1/1) exhibited a high open circuit voltage of 1.41 V, a peak power density of 66.84 mW cm −2 , a large specific capacity of 818.88 mA h g Zn −1 , and cycling for 20 h but with deactivation upon cycling. Infiltration of mesopores in SBA-15 hard template with phenanthroline complexes of Fe 3+ and Co 2+ allowed the dispersion of nitrogen, iron and cobalt species on the surface of the CMK-3 replica, as heterogeneous catalyst for the ORR and OER reactions.