Enabling Iron-Based Highly Effective Electrochemical Water-Splitting and Selective Oxygenation of Organic Substrates through In Situ Surface Modification of Intermetallic Iron Stannide Precatalyst

A strategy to overcome the unsatisfying catalytic performance and the durability of monometallic iron-based materials for the electrochemical oxygen evolution reaction (OER) is provided by heterobimetallic iron–metal systems. Monometallic Fe catalysts show limited performance mostly due to poor conductivity and stability. Here, by taking advantage of the structurally ordered and highly conducting FeSn₂ nanostructure, for the first time, an intermetallic iron material is employed as an efficient anode for the alkaline OER, overall water-splitting, and also for selective oxygenation of organic substrates. The electrophoretically deposited FeSn₂ on nickel foam (NF) and fluorine-doped tin oxide (FTO) electrodes displays remarkable OER activity and durability with substantially low overpotentials of 197 and 273 mV at 10 mA cm⁻², respectively, which outperform most of the benchmarking NiFe-based catalysts. The resulting superior activity is attributed to the in situ generation of α-FeO(OH)@FeSn₂ where α-FeO(OH) acts as the active site while FeSn₂ remains the conductive core. When the FeSn₂ anode is coupled with a Pt cathode for overall alkaline water-splitting, a reduced cell potential (1.53 V) is attained outperforming that of noble metal-based catalysts. FeSn₂ is further applied as an anode to produce value-added products through selective oxygenation reactions of organic substrates.