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 FeO stands out as one of the most credible candidates in terms of cost and abundance. However, FeO 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 FeO 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, FeO was implemented in a heterojunction/composite, doped, carbon supported, crystal facet tuned system, as well as in metal organic framework (MOF) systems. Furthermore, FeO 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 FeO in electrolysis is limited, and hence, intense and strategically focused research is vital for converting FeO into a commercially viable, cost-effective, and efficient catalyst material.