Reversing the Hydrogenation Pathways of Nitrogen-Containing Intermediates for the Kinetics-Matched Urea...

Urea electrosynthesis from carbon dioxide (CO₂) and nitrate (NO₃ ^-) is a promising sustainable route. However, the kinetic mismatch between key intermediates remains the major challenge for achieving selective C‒N coupling. Herein, indium-doped titanium dioxide (In-TiO₂) nanofibers were developed to regulate the hydrogenation pathway for realizing kinetics-matched urea electrosynthesis. In situ spectroscopic analysis and theoretical calculations reveal that In doping reverses the hydrogenation pathway of nitrogen-containing intermediates from the Eley-Rideal (E-R) to the Langmuir-Hinshelwood (L-H) mechanism. This shift is attributed to the sufficient *H supply guaranteed by the regulated interfacial water structure. Such reversed hydrogenation pathway balances *H utilization between CO₂ and NO₃ ^- reduction, enabling well-matched formation kinetics of key intermediates for efficient C‒N coupling. Owing to the above merits, In-TiO₂ achieved the remarkable average urea yield rate of 56.5 mmol h^-1 g^-1 with a Faradaic efficiency of 32.8%. This work provides mechanistic insights into the hydrogenation pathways regulation for efficient urea electrosynthesis.