V₂O₃-regulated oxygen-rich doped carbon as core-shell nanostructures for stable and efficient hydrogen generation via urea electrolysis

Utilizing urea-assisted hydrogen production with favorable thermodynamic potential to replace conventional slow and energy-intensive water electrolysis offers a promising alternative for green hydrogen generation, while simultaneously treating urea-containing organic wastewater. However, the sluggish six-electron transfer kinetics of the UOR (Urea Oxidation Reaction) and the inherent proneness to deactivation of current non-noble metal catalysts severely restrict urea’s application in hydrogen production. This work designed a core–shell nanocolumnar electrocatalyst featuring with oxygen partial pressure regulated porous oxygen-doped amorphous carbon as the outer layer and V₂O₃ as the inner core (V₂O₃@CC). Benefiting from abundant active sites comprising defects and oxygen-functional groups in the shell layer, coupled with high porosity, the catalyst V₂O₃@CC exhibits exceptional catalytic activity for both the UOR and HER (Hydrogen Evolution Reaction). Furthermore, it demonstrates exceptional long-term stability (157 h @10 mA cm⁻²) enabled by the protective carbon coating. Additionally, an integrated water-urea electrolysis cell is further assembled, achieving an ultralow overpotential of 0.11 V (@10 mA cm⁻²) and maintaining 80-hour stability at high current density (50 mA cm⁻²). Therefore, coating the core catalytic layer with amorphous carbon achieved efficient and highly stable overall urea electrolysis.