Are transition metal phthalocyanines active for urea synthesis via electrocatalytic coupling of CO₂ and N₂?

Electrocatalytic coupling of CO₂ and N₂ to synthesize urea presents a promising approach to address global energy and environmental challenges. Despite the potential, developing an efficient catalyst capable of activating both CO₂ and N₂ while suppressing side reactions remains a significant challenge. Recent studies have indicated that CuPc and CoPc exhibit notable activity in this process. Herein, we report a theoretical analysis of the catalytic performance of 3d-5d transition metal phthalocyanines (MPcs) in the electrocatalytic urea synthesis reaction. Our findings reveal that MPcs generally exhibit limited activity due to the poor competitiveness of N₂ for adsorption sites and the high energy barrier associated with CO-N₂ coupling, which hinders their ability to compete with CO reduction and/or N₂ reduction pathways. Furthermore, the coupling between CO and NH₂* is either insufficient for N₂ reduction or is outcompeted by ammonia formation. We propose that enhancing N₂ adsorption could facilitate C-N coupling, offering a potential strategy for the design of single-atom catalysts aimed at improving urea synthesis efficiency.