Transition metal anchored on g-C3N4 as a promising single-atom-electrocatalyst for CO2 and N2 coupling to synthesis urea: A theoretical study

The advancement of a proficient catalyst to facilitate the electrochemical generation of urea (CO(NH2)2) from carbon dioxide (CO2) and nitrogen (N2) in aqueous media at ambient conditions is crucial in the modern materials field. In this study, theoretical calculations were employed to investigate the catalytic potential of transition metal (TM) atoms anchored on graphitic carbon nitride (g-C3N4) for urea electrosynthesis, with TM including Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh and Pd. Our findings demonstrate that Sc, Ti, V and Y@g-C3N4 sheets were screened according to three screening criteria and Ti@g-C3N4 showcases most probable catalytic efficacy in the electrochemical generation of urea. Ti@g-C3N4 retains considerable thermal stability at 500 K, highlighting its suitability for practical applications. The urea synthesis process on Ti@g-C3N4 transpires with a minimal energy barrier of just 0.41 eV, accentuating its potential catalytic capabilities. The electronic structure analysis also supported this conclusion. This study introduces a catalyst screening framework for the electrochemical transformation of CO2 and N2 based on theoretical study, laying a theoretical foundation for the experimental study of TM@g-C3N4 catalyzed CN coupling for the synthesis of urea.