Construction of orderly hierarchical FeOOH/NiFe layered double hydroxides supported on cobaltous carbonate hydroxide nanowire arrays for a highly efficient oxygen evolution reaction

An orderly hierarchical hybrid electrode has been constructed for the oxygen evolution reaction (OER) in this work. FeOOH/NiFe layered double hydroxide (LDH) nanoplates are grown on cobaltous carbonate hydroxide nanowire arrays (CCH NAs) directly, with nickel foam (NF) as a conductive substrate. This FeOOH/NiFe LDHs@CCH NAs-NF with orderly hierarchical construction of FeOOH/NiFe LDH nanoplates supported on cobaltous carbonate hydroxide nanowire arrays exhibits superior activity for the OER, which delivers current densities of 10 and 100 mA cm−2 at overpotentials of 220 and 290 mV, respectively, and excellent stability at 10, 100, 300, and 500 mA cm−2 for 40 hours in 1 M KOH. For commercial applications, an alkaline polymer electrolyte water electrolyzer (APEWE) with this electrode shows 1.768 V at 500 mA cm−2, exhibiting higher working current density than typical commercial alkaline water electrolyzers. A chronopotentiometry test in 1 M KOH at 500 mA cm−2 reveals that the performance of the APEWE is stable at ∼1.8 V for about 100 hours.