Efficient Urea Electrosynthesis from CO and Nitrate on Amorphous TiS

Electrosynthesis of urea via co-electrolysis of CO and NO (EUCN) offers a promising avenue for simultaneously addressing environmental concerns and producing valuable urea. In this study, we report that amorphous TiS (a-TiS) with rich S-vacancies (S) serves as an effective and robust EUCN catalyst. In a flow electrolyzer, a-TiS achieves the maximum urea-Faradaic efficiency of 34.5 % and urea yield rate of 30.6mmol h g at -0.7 V. RHE, significantly outperforming crystalline TiS 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 site to promote *NH/*CO formation and their CN coupling, whilst suppressing the competing hydrogen evolution and NO-to-NH reactions, thus enabling a highly selective EUCN for urea synthesis.