In situ construction of FeO@FeOOH for efficient electrocatalytic urea oxidation.

Substituting water oxidation half of water splitting with anodic oxidation of urea can reduce the cost of H production and provide an avenue for treating urea-rich wastewater. However, developing an efficient and stable electrocatalyst is necessary to overcome the indolent kinetics of the urea oxidation reaction (UOR). Accordingly, we have used the Schikorr reaction to deposit FeO particles on the nickel foam (FeO/NF). Results from the various analysis indicated that under the operational conditions, FeO underwent surface reconstruction to produce a heterolayered structure wherein a catalytically active FeOOH layer encased a conducting FeO. FeO/NF outperformed RuO as a UOR catalyst and delivered a current density of 10 50 and 100 mA cm at low applied potentials of 1.38 1.42 and 1.46 V, respectively, with a Tafel slope of 28 mV dec. At the applied potential of 1.4 V, FeO/NF demonstrated a turnover frequency (TOF) of 2.8 × 10 s, highlighting its superior intrinsic activity. In addition, a symmetrical urea electrolyzer constructed using FeO/NF produced the current density of 10 mA cm at a cell voltage of 1.54 V.