Efficient urea electrosynthesis from CO2 and nitrate on amorphous TiS2

Electrosynthesis of urea via co-electrolysis of CO₂ and NO₃^- (EUCN) offers a promising avenue for simultaneously addressing environmental concerns and producing valuable urea. In this study, we report that amorphous TiS₂ (a-TiS₂) with rich S-vacancies (S_v) serves as an effective and robust EUCN catalyst. In a flow electrolyzer, a-TiS₂ achieves the maximum urea-Faradaic efficiency of 34.5 % and urea yield rate of 30.6mmol h^-1 g_cat^-1 at -0.7 V. RHE, significantly outperforming crystalline TiS₂ and most reported EUCN catalysts. A combination of extensive atomic characterizations, theoretical computations and in situ spectroscopic measurements reveals the synergistic catalysis of Ti site and Ti-S_v site to promote *NH₂/*CO formation and their CN coupling, whilst suppressing the competing hydrogen evolution and NO₃^--to-NH₃ reactions, thus enabling a highly selective EUCN for urea synthesis.