Applications of Ferric Oxide in Water Splitting by Electrolysis: A Comprehensive Review

In water electrolysis, the use of an efficient catalyst derived from earth-abundant materials which is cost-effective and stable is essential for the economic sustainability of hydrogen production. A wide range of catalytic materials have been reported upon so far, among which Fe₂O₃ stands out as one of the most credible candidates in terms of cost and abundance. However, Fe₂O₃ faces several limitations due to its poor charge transfer properties and catalytic ability; thus, significant modifications are essential for its effective utilization. Considering the future of water electrolysis, this review provides a detailed summary of Fe₂O₃ materials employed in electrolytic applications with a focus on critically assessing the key electrode modifications that are essential for the materials' utilization as efficient electrocatalysts. With this in mind, Fe₂O₃ was implemented in a heterojunction/composite, doped, carbon supported, crystal facet tuned system, as well as in metal organic framework (MOF) systems. Furthermore, Fe₂O₃ was utilized in alkaline, seawater, anion exchange membrane, and solid oxide electrolysis systems. Recently, magnetic field-assisted water electrolysis has also been explored. This comprehensive review highlights the fact that the applicability of Fe₂O₃ in electrolysis is limited, and hence, intense and strategically focused research is vital for converting Fe₂O₃ into a commercially viable, cost-effective, and efficient catalyst material.