Precisely Bonded Fe─Cu Diatomic Sites with Nitrogen‐Bridged Coordination on Hollow C<sub>3</sub>N<sub>4</sub> Spheres for Efficient C─N Coupling and Selective Photocatalytic Urea Synthesis
Muhammad Irfan Ahmad, Xie Quan, Haokun Bai, Yanming Liu, Shuo Chen, Hongtao Yu
Abstract
Abstract The photocatalytic synthesis of urea from CO 2 and N 2 co‐reduction presents a promising alternative to the conventional energy‐intensive Haber–Bosch process. However, competitive adsorption on the catalyst surface often limits selectivity and yield. Here, we designed hollow graphitic carbon nitride (g‐C 3 N 4 ) spheres, which serve as a high surface area scaffold for precise anchoring of Fe─Cu diatomic sites. Hollow architecture enhances light harvesting via inner‐scattering effects and charge separation. Each Fe─Cu site is coordinated with two nitrogen atoms, forming N 2 ─Fe 1 ─Cu 1 ─N 2 /C 3 N 4 DAC (hereafter referred to as FeCu/CN), which enables cooperative activation of CO 2 and N 2 , in contrast to monodispersed diatomic (Fe+Cu/CN), and single‐atom catalysts (Fe/CN, Cu/CN). The FeCu/CN bonded pairs serve as highly efficient active centers, facilitating the synergistic adsorption and activation of multiple reactants. Specifically, during the co‐reduction of CO 2 and N 2 , the Fe 1 site preferentially adsorbs and activates CO 2 , while bonded Cu 1 sites stabilize N 2 on FeCu/CN and enable synergistic C─N coupling through the formation of *NCON intermediates. As a result, the FeCu/CN achieves an exceptional urea yield of 7.40 mg·g cat −1 ·h −1 with a 38.58% selectivity under visible light irradiation. Our findings highlight the crucial role of atomic‐level coordination in multireactants and offer insights into the C─N coupling for value‐added products using CO 2 and N 2 as feedstock.