Speaker: Prof. Lei Wang, professer from the National University of Singapore

Title: Molecular CO₂ Reduction: Selectivity and Carbon Efficiency

Time: 14:30 September 1st, 2025 (Monday)

Venue: No.2 conference room on the 3rd floor, Building No.5

Host: Prof. Shenlong Zhao

Info. of Speaker：

Lei Wang completed his B.S. and M.S. in Dalian University of Technology (2011), and doctorate at KTH Royal Institute of Technology in 2015, where he studied water oxidation based on molecular catalysts. In 2016, he joined Stanford University as a Wallenberg-Stanford postdoc fellow. He began his current position at National University of Singapore at the end of 2020. He has published 50 peer reviewed scientific papers in international journals like Nat. Catal., JACS, PNAS, Angew. Chem. Int. Edit., Nat. Commun., Adv. Mat. etc. He was awarded as NRF Fellow in Singapore at 2021. His current research focuses on catalyst discovery and understanding reaction mechanisms for electrochemical CO₂ reduction and green H₂ production.

Abstract:

Electrocatalytic synthesis of urea presents a promising approach to closing the artificial nitrogen cycle. However, a major challenge arises from the sluggish C–N coupling step in urea formation compared to other competing electrochemical steps involving nitrate and CO₂ reduction, ultimately limiting the urea selectivity and energy efficiency during the co-electroreduction of nitrate and CO₂. In this study, we identify *NO₂ as a key intermediate that governs urea activity and selectivity as it can either undergo hydrogenation or couple with CO₂ to form the desired C–N bond. Our theoretical investigations reveal that a decrease in the adsorption energy of *NO₂ on Cu can suppress *NO₂ hydrogenation while enhancing its coupling with CO₂ to favor C–N bond formation. We further discover that doping of Cu with boron increases the energy requirement for *NO₂ hydrogenation and lowers the energy barrier for C–N coupling involved in the formation of *NO₂CO₂. Encouragingly, with the synthesized boron-doped Cu catalysts, we achieve a high urea Faradaic efficiency exceeding 80% at a low overpotential of −0.22 V vs the reversible hydrogen electrode, at a partial current density of approximately 30 mA cm^–2. In contrast, the pristine Cu only shows a low urea selectivity (19%) and production rate (<5 mA cm^–2) under identical conditions. Furthermore, a comprehensive life-cycle assessment underscores the significance of abundant nitrate sources for urea electrosynthesis. However, the relatively low current density hinders the practical implementation of this technology. Hence, we have also spent some preliminary efforts on enhancing the urea production current density while maintaining an appreciable selectivity. In this case, a Fe-based catalyst was investigated. Overall, we demonstrated >100 mA cm^–2 partial current density for urea production with >50% Faradaic efficiency.

.