Shifting the Product Pathway of N2 and CO Electro-Coupling from Urea to Formamide and Ammonia on 3d Dual-Atom Catalysts

Abstract

While the electrochemical coupling of N2 and CO is traditionally directed toward urea synthesis, a co-production strategy yielding formamide (NH2CHO) and ammonia (NH3) offers an alternative approach to enhance the carbon and nitrogen utilization efficiency. Combining density functional theory calculations with a constant-potential model, this study evaluates a screening matrix of 27 graphene-supported dual-atom catalyst (DAC) configurations, comprising nine 3d transition metals each evaluated at three distinct bimetallic distances. Divanadium (V2) systems are identified as viable candidates for this co-synthesis pathway. The V2 configuration enables a side-on N2 adsorption mode to activate the N≡N bond, while its variable metal–metal spacing allows systematic investigation of distance-dependent catalytic trends. Mechanistic analysis reveals that co-adsorbed N2 and CO undergo direct C–N coupling to generate a tower-like *NCON intermediate. During subsequent hydrogenation, due to the intrinsic affinity of V centers for the N atom, one of the C–N bonds is cleaved. This dissociation establishes a dual-product pathway in which the fragment retaining the intact C–N bond is reduced to NH2CHO while the detached nitrogen species yields NH3. The irreg-5-V2N7@G catalyst, featuring a moderate bimetallic spacing, balances intermediate binding to provide a C–N coupling barrier of 0.31 eV, an onset potential of −0.8 V versus RHE at pH 14, and a wide potential window. These findings demonstrate a method for leveraging spontaneous intermediate dissociation to maximize the atom economy of carbon and nitrogen utilization.