Nanoparticulate WN/Ni3C Coupling in Ceramic Coatings for Boosted Urea Electro‐Oxidation.

Urea electrolysis can convert urea from urea‐rich wastewater to hydrogen for environmental protection and sustainable energy production. However, the sluggish kinetics of urea oxidation reaction (UOR) requires valence‐variable sites that are generally active at high anodic overpotentials. Herein, a robust ceramic coating is constructed with coupled tungsten nitride (WN)/nickel carbide (Ni3C) nanoparticles to achieve valence‐stable catalytic sites with outstanding UOR performance. Various characterization results indicate strong interfacial electron transfer from WN to Ni3C in coupled nanoparticles, which enables reservation of Ni2+ sites without self‐oxidation during UOR, quite distinct from the kinetically slow Ni3+OOH‐catalyzed UOR pathway. Theoretical calculations show that the coupled effect in WN/Ni3C leads to enhanced electron transfer from catalytic sites to adsorbed urea, and W sites are thermodynamically favorable for UOR. This efficiently lowers the barrier of rate‐determining step (RDS: *CO‐N2 → *CO·OH), thus enabling fast UOR kinetics and a low potential of 1.336 V at 100 mA cm−2, which identifies this ceramic coating as one of the best UOR electrocatalysts. This work opens a new avenue for design of stable and active sites in ceramics coatings toward advanced electrocatalytic applications. [ABSTRACT FROM AUTHOR]