Active Microstructure Transformation and Enhanced Stability of Iron Foam Derived from Industrial Water Oxidation

Tracking microstructure transformation under industrial conditions is significant and urgent for the development of oxygen evolution reaction (OER) catalysts. Herein, employing iron foam (IF) as an object, we closely monitor related morphologies and composition evolution under 300 mA cm^-2 at 40 °C (IF-40-t)/80 °C (IF-80-t) in 6 M KOH and find that the OER activity first increases and then decreases with the continuous generation of FeOOH. Moreover, the reasons for different tendencies of Tafel slope, double-layer capacitance, and impedance for IF-40-t/IF-80-t have been investigated thoroughly. In detail, the OER activity of IF-40-t is governed by electron and mass transport, while for IF-80-t, the dominating factor is electron transfer. Further, to improve the stability, guided by the above results, two versatile methods that do not sacrifice electron and mass transport have been proposed: surface coating and dynamic interface construction. The synchronous improvements of stability and activity are deeply revealed, which may provide inspiration for catalyst design for industrial applications.