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

Abstract

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.