Deciphering the active origin for urea oxidation reaction over nitrogen penetrated nickel nanoparticles embedded in carbon nanotubes.

Urea electrooxidation with favorable thermodynamic potential is highly anticipated but suffering from sluggish kinetics. Deciphering the activity origin and achieving rational structure design are pivotal for developing highly efficient electrocatalyst for urea oxidation reaction (UOR). Herein, nitrogen penetrated nickel nanoparticles confined in carbon nanotubes (Ni-NCNT) is successfully achieved to drive UOR. Active origin of Ni-NCNT is decoded to be the in-situ generated NiO(OH) according to comprehensive analysis. The electrophilic Ni and protophilic OH could targeted capture O and H atoms from urea, respectively, achieving molecule activation and accelerating the subsequent proton coupled electron transfer reactions. Nitrogen penetration is identified to promote prior formation of NiO(OH) and push up the d band center of Ni-NCNT, enhancing urea adsorption and subsequent molecule cleavage reactions. As a result, Ni-NCNT exhibits superior UOR performance. This work supplies valuable insights for the rational design and construction of efficient nickel-based catalyst for driving UOR.