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-N-2.-> *CO center dot OH), thus enabling fast UOR kinetics and a low potential of 1.336 V at 100 mAcm(-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.

Automated summary

A novel ceramic coating with coupled tungsten nitride/nickel carbide nanoparticles has been developed for urea electrolysis. The coupled effect enables valence-stable catalytic sites, leading to enhanced electron transfer and improved kinetics of the urea oxidation reaction. The ceramic coating shows outstanding performance as a urea oxidation reaction electrocatalyst, making it a promising candidate for advanced electrocatalytic applications.