Síntesis, caracterización y aplicaciones de nano y microestructuras de α-Fe₂ O₃, Cr₂O₃ y h-MoO₃ y sus "composites" con formas alotrópicas de carbono

Los óxidos semiconductores han generado un creciente interés en los últimos años, debido a sus interesantes propiedades físico-químicas y sus potenciales aplicaciones en el campo de la optoelectrónica, la catálisis y el almacenamiento de energía. También, ha crecido el interés en las propiedades magnéticas de estos materiales, debido, entre otros motivos, a sus prometedoras aplicaciones en dispositivos de almacenamiento magnético o en medicina. Mediante el control de la morfología, el tamaño, la introducción de dopantes y la síntesis de materiales compuestos (composites) basados en formas alotrópicas de carbono, dichas aplicaciones pueden mejorarse y otras nuevas desarrollarse. En el marco de esta tesis doctoral se ha investigado la síntesis de nanopartículas de -Fe2O3 y Cr2O3 y microestructuras de h-MoO3, así como la fabricación de composites con grafito, grafeno y óxido de grafeno, para conseguir mejorar sus propiedades de cara al desarrollo de aplicaciones en el campo de la optoelectrónica y el almacenamiento de energía en baterías de ion litio. Para ello se ha llevado a cabo una amplia y adecuada caracterización morfológica, estructural, óptica, magnética y electroquímica de todas las muestras..

Study of Cr2O3 nanoparticles supported on carbonaceous materials as catalysts for O2 reduction reaction

A series of chromium oxides (Cr2O3) nanoparticles supported on different carbonaceous material, namely: graphene, graphene oxide (GO) and graphite, were synthetized by precipitation of the salt precursors with precipitant (ammonia) and the subsequent thermal treatment. The catalytic activity of these composites and the Cr2O3 nanoparticles have been analysed by Koutecky-Levich (KL) and rotating ring-disc electrode methods and the results have been discussed following a model proposed here, which considers the O2 electrosorption as the rate determining step. Among them, graphite and graphene based composites have better catalytic activities and their behaviours agree with the proposed treatment: logarithm dependent of the intercept and nondependent slopes values of the KL plots with the potential. Cr2O3-graphite shows a mechanism interchanging 4 e-, which has been attributed to a graphite- Cr2O3 nanoparticles interaction. Besides, Cr2O3-graphite-based electrodes have been tested as cathode in a Zn/PVA-KOH/air battery, confirming its good properties to be applied as positive electrode in metal-air batteries.The authors thank the financial support from Fundación Séneca (Región de Murcia, Spain; Ref: 20985/PI/18), Spanish Agencia Estatal de Investigación (PID2019-104272RB-C55/AEI/10.13039/501100011033, CTQ2017-90659-REDT and PID2019-106097 GB/AEI/10.13039/501100011033), MINECO (projects MAT2017-84118-C2-2-R and MAT2017-82252-R) and Banco Santander-UCM (project PR87/19-22613). The authors also acknowledge Victor Galindo Garre for providing R-Studio scripts for data analysis

Commercially Accessible High-Performance Aluminum-Air Battery Cathodes through Electrodeposition of Mn and Ni Species on Fuel Cell Cathodes

2023 Acuerdos transformativos CRUE.This study presents a cost-effective method for producing high-performance cathodes for aluminum-air batteries. Commercial fuel cell cathodes are modified through electrodeposition of nickel and manganese species. The optimal conditions for electrodeposition are determined using a combination of structural (Raman, SEM, TEM) and electrochemical (LSV, EI, discharge curves) characterization techniques. The structural analysis confirms successful incorporation of nickel and manganese species onto the cathode surface. Electrochemical tests demonstrate enhanced electrochemical activity compared to unmodified cathodes. By combining the favorable properties of electrodeposited manganese species with nickel species, a high-performance cathode is obtained. The developed cathode exhibits capacities of 50 mA h cm−2 in aluminum-air batteries across a wide range of current densities. The electrodeposition method proves effective in improving electrochemical performance. A key advantage of this method is its simplicity and cost-effectiveness. The use of commercially available materials and well-established electrodeposition techniques allows for easy scalability and commercialization. This makes it a viable option for large-scale production of high-performance cathodes for the next-generation energy storage devices.Depto. de Física de MaterialesDepto. de Química InorgánicaFac. de Ciencias FísicasFac. de Ciencias QuímicasTRUEpubAPC financiada por la UC