Electrochemically Fabricated NiP/Cu Electrode for Enhanced Urea Electrooxidation in Alkaline Media

Galvanostatic preparation of nickel–phosphide (NiP) coatings on Cu substrates by electrodeposition using current densities of 0.5–5 mAcm − 2 is described and their application to the urea oxidation in alkaline media is evaluated. The NiP/5 catalyst showed the highest electrocatalytic performance in 1 M KOH with the presence of 0.33 M urea than all tested electrodes, providing a high current density (5.87 mAm − 2 g) with a higher oxidation potential (0.56 V), which was 1.5‐fold and ∼12‐fold greater than that of Ni and NiP/0.5, respectively. The excellent catalytic performance of NiP/5 can be attributed to synergistic contributions of a fully amorphous structure, phosphorus composition and rough porous surface morphology. The amorphous NiP/5 catalyst presented abundant unsaturated active sites and rapid adsorption/desorption of urea‐related intermediates, whereas the phosphorus incorporation facilitated electronic modulation and rapid in situ formation of electroactive NiOOH species. Electrochemical impedance spectroscopy further confirmed the enhanced charge‐transfer kinetics; with urea addition, the charge‐transfer resistance decreases significantly from 61.32 to 5.28 Ωcm 2 . Chronoamperometric measurements showed that the catalyst was also stable during long‐term electrolysis. These results suggest that using the appropriate current density for electrodeposition is a viable approach to engineering the morphology, composition and electronic structure of amorphous NiP catalysts for efficient urea electrooxidation.