Dual-Silicon-Doped Graphitic Carbon Nitride Sheet: An Efficient Metal-Free Electrocatalyst for Urea Synthesis

Searching for an alternative nonhazardous catalyst for direct urea synthesis that avoids the traditional route of NH 3 synthesis followed by CO 2 addition is a challenging field of research nowadays. Based on first-principles calculations, we herein propose a novel electrocatalyst comprising of totally nonmetal earth abundant elements (dual-Si doped g-C 6 N 6 sheet) which is capable of activating N 2 and making it susceptible toward direct insertion of CO into the N–N bond, producing *NCON* which is the precursor for urea production by direct coupling of N 2 and CO 2 followed by multiple proton coupled electron transfer processes. Remarkably, the calculated onset potential for urea production is much less than that of NH 3 synthesis and hydrogen evolution reactions, and also the faradaic efficiency is nearly 100% for production urea over ammonia, which promotes exclusive electrocatalytic urea synthesis by suppressing the NH 3 synthesis as well as hydrogen evolution reactions.