Semi-sacrificial template growth of FeS/Fe2O3 heterogeneous nanosheets on iron foam for efficient oxygen evolution reaction

The efficiency of water electrolysis is greatly hindered by complex electron-proton transfer process of oxygen evolution reaction (OER). Exploiting cost-efficient OER electrocatalytic materials to improve the performance of overall water splitting is necessary. Partial chemical etching of iron foam (IF) with glacial acetic acid, using IF as the metal source and substrate, to form vertically aligned FeS/Fe2O3 heterogeneous nanosheets on the IF (FeS/Fe2O3/IF) can obtain a hierarchical electrode to meet the above requirements. The nanosheets with heterogeneous interfaces in situ grown on IF can adjust electronic structure and expose more active sites, resulting in great improvement of catalytic activity and stability. FeS/Fe2O3/IF requires a small overpotential of 266.5 mV to attain 10 mA cm−2 and its Tafel slope is 51.17 mV dec−1. It is worth noting that FeS/Fe2O3/IF can work continuously for 50 h at high current density, which proves the strong stability during the OER process. The FeS/Fe2O3/IF has high electrocatalytic activity and stability, and can be used as a good candidate material for electrocatalytic OER in industrial manufacture.