Electrochemical tuning of nickel molybdate nanorod arrays towards promoted electrocatalytic urea oxidization

Urea electrolysis enables simultaneous energy-saving hydrogen production and wastewater purification at a small thermodynamic potential of 0.37 V; however, the total energy-utilization efficiency is still substantially restricted by the sluggish kinetics of the urea oxidization reaction (UOR) at the anode. In this work, an electrochemical tuning strategy has been employed to obtain a Ni (III)-enriched catalyst by starting from NiMoO4 center dot xH2O nanorod arrays. It has been found that the electrochemical tuning not only modifies the valency state of Ni but also causes a dramatic change in stoichiometry and microstructure of the material, leading to significantly improved activities for UOR under alkaline conditions. Notably, the obtained catalyst delivers a current density of 100 mA cm-2 for UOR at the potential of only 1.36 V vs RHE, which surpasses the bestreported values for UOR catalysis at the same applied potential, demonstrating the great promise of the electrochemical tuning strategy in rational modifications of material towards promoted electrocatalysis.