Carbon monoxide electroreduction (COER) has been a key part of tandem electrolysis of carbon dioxide (CO₂), in which searching for high catalytic performance COER electrocatalysts remains a great challenge. Herein, by means of density functional theory (DFT) computations, we explored the potential of a series of transition metal atoms anchored on N-doped γ-graphyne (TM@N-GY, TM from Ti to Au) as the COER electrocatalysts. We found that the final product selectivity of these single-atom catalysts depended on the position of the metal atom in the periodic table, with metals in the front and middle of each periodic period exhibiting high selectivity for CH₄, while metals in the back producing CH₃OH. Machine learning (ML) found that metal atomic number was intrinsic to the difference in COER performance of these single-atom catalysts (SACs). The free energy changes showed that Mn@N-GY and Ni@N-GY exhibited outstanding COER catalytic performance for producing CH₄ and CH₃OH, respectively. Our results provide theoretical and experimental guidance for designing efficient COER catalysts to generate C₁ products.

Urea synthesis through the simultaneous electrocatalytic reduction of N₂ and CO₂ molecules under ambient conditions holds great promises as a sustainable alternative to its industrial production, in which the development of stable, highly efficient, and highly selective catalysts to boost the chemisorption, activation, and coupling of inert N₂ and CO₂ molecules remains rather challenging. Herein, by means of density functional theory computations, we proposed a new class of two-dimensional nanomaterials, namely, transition-metal phosphide monolayers (TM₂P, TM = Ti, Fe, Zr, Mo, and W), as the potential electrocatalysts for urea production. Our results showed that these TM₂P materials exhibit outstanding stability and excellent metallic properties. Interestingly, the Mo₂P monolayer was screened out as the best catalyst for urea synthesis due to its small kinetic energy barrier (0.35 eV) for C–N coupling, low limiting potential (−0.39 V), and significant suppressing effects on the competing side reactions. The outstanding catalytic activity of the Mo₂P monolayer can be ascribed to its optimal adsorption strength with the key *NCON species due to its moderate positive charges on the Mo active sites. Our findings not only propose a novel catalyst with high-efficiency and high-selectivity for urea production but also further widen the potential applications of metal phosphides in electrocatalysis.