NiCo2O4 nanoparticles supported on mesoporous carbon : a bifunctional electrocatalyst for rechargeable Zn-air and Zn-air flow batteries

An energy transition based on the valorization of abundant renewable resources is needed to reduce the high consumption of fossil fuels and their negative impact in the environment in agreement with the SDG of the United Nations. To achieve this goal, robust energy storage systems need to be developed. Among them, rechargeable Zn-air batteries (rZnAB) are of great interest due to their high energy density (9653 Wh L-1) and the possibility of using aqueous electrolytes. The operation of the cathode relies on two oxygen reactions: i) oxygen reduction reaction (ORR) during the discharge, ii) oxygen evolution reaction (OER) during the charge. Both reactions exhibit slow kinetics. For instance, it is necessary to obtain a bifunctional electrocatalyst with high conductivity, selective to avoid side reactions such as H2O2 production, and stable to increase the battery lifetime. This thesis focused on the development of a bifunctional electrocatalyst based on spinel-like NiCo2O4 nanoparticles dispersed on a porous carbonaceous support with high surface area and pore volume. For this purpose, the textural properties of the carbonaceous support (MC), the deposition method of the metal precursors (hydrothermal (HT) and incipient wetness impregnation (I)) and the type of atmosphere (N2, Air and 20% O2/80% N2) used during thermal treatment at different temperatures (300°C and 700 °C) have been evaluated in order to control the localization, particle size, surface chemistry and acidic properties of NiCo2O4. Using the HT methodology, and calcination at 300 oC under 20% O2/80% N2, NiCo2O4 nanoparticles of ∼9 nm located inside the mesopores of the MC support were obtained, the material exhibited high specific surface area and pore volume, with a surface enriched in uncoordinated Ni2+ and Co2+ species, and high density of Lewis acid sites. The NiCo2O4/MC-HTs demonstrated efficient bifunctional activity in ORR/OER with ΔE of 1.03 V and they were evaluated in a rZAB, powering a 2 mW laser for 17 h, and in a zinc-air flow battery (ZAFB), it successfully powered 39 red LED bulbs displaying the INRS logo for over 100 h. In conclusion, this PhD thesis contributes to the understanding of the impact of textural properties, synthesis conditions, and surface chemistry of NiCo2O4-based materials to obtain bifunctional electrocatalytic activity in the cathode of rZABs; and in this way advancing the scientific knowledge of metal-air batteries as energy storage devices.

• Autores: Díaz Escobar, Cristian Camilo
• Tipo de recurso: Doctoral thesis
• Fecha de publicación: 2025
• Institución: Universidad de Antioquia
• Repositorio: Repositorio UdeA
• Idioma: eng
• OAI Identifier: oai:bibliotecadigital.udea.edu.co:10495/47149
• Acceso en línea: https://hdl.handle.net/10495/47149
• Palabra clave: Electroquímica; Electrochemistry; Electrocatálisis; Electrocatalysts; Catálisis; Catalysis; Baterías Metal Aire; Carbón mesoporoso; Batería recargable de Zn-aire (rZAB); Reacciones de reducción y evolución del oxígeno; ODS 7: Energía asequible y no contaminante. Garantizar el acceso a una energía asequible, fiable, sostenible y moderna para todos; ODS 13: Acción por el Clima. Adoptar medidas urgentes para combatir el cambio climático y sus efectos
• Rights: openAccess
• License: http://creativecommons.org/licenses/by-nc-sa/4.0/