Electrochemical reduction of hematite-based ceramics in alkaline medium: Challenges in electrode design


Electrochemical reduction of low-conductive hematite-based ceramics represents a novel approach for iron recovery and waste valorisation. The process itself allows a flexible switching between hydrogen generation and iron reduction, important for the intermittent renewable-energy-powered electrolytic process. The present study focuses on the direct electrochemical reduction of aluminium-containing hematite in strong alkaline media. Within this scope, the reduction mechanisms of porous and dense cathodes, with 60%, 37% and 3% of open porosity, were investigated using different types of electrodes configuration: nickel-foil and Ag-modified nickel-foil supported configuration (cathodes facing or against the counter electrode), and nickel-mesh supported configuration. The efficiency of the iron reduction was compared for different electrode concepts. The results highlight the importance of electrolyte access to the interface between the metallic current collector and ceramic cathode for attaining reasonable electroreduction currents. Both excessively porous and dense ceramic cathodes are hardly suitable for such reduction process, showing a necessity to find a compromise between mechanical strength of the electrode and its open porosity, essential for the electrolyte access. (C) 2019 Elsevier Ltd. All rights reserved.






Lopes, DV; Ivanova, YA; Kovalevsky, AV; Sarabando, AR; Frade, JR; Quina, MJ

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This work was supported by the FCT grant PD/BD/114106/2015, by the European Commission (project SIDERWIN-DLV-768788 Horizon 2020/SPIRE10) and CICECO-Aveiro Institute of Materials (ref. UID/CTM/50011/2019), financed by COMPETE 2020 Program and National Funds through the FCT/MEC and when applicable cofinanced by FEDER under the PT2020 Partnership Agreement.

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