Magnetic Field‐Induced Mass Transfer Acceleration and Spin Polarization for Highly Efficient Photocatalytic Urea Synthesis

ABSTRACT Different from traditional industrial urea synthesis using NH 3 and CO 2 , heterogeneous photocatalysis enables direct urea synthesis from N 2 and CO 2 in aqueous, where water acts as both solvent and hydrogen source. Its low yield is mainly restricted by poor reactant activation efficiency, mismatched reaction kinetics, slow C─N coupling and slow gas mass transfer via water hydrogen bond networks. Herein, an external magnetic field was adopted to boost photocatalytic urea synthesis. Upon magneto‐photocatalysis, water hydrogen bonds were disturbed to form gas diffusion channel and release sufficient hydrogen protons. Driven by the Lorentz force and magnetohydrodynamic convection, electron‐proton interactions were strengthened. Meanwhile, spin‐polarized electrons and regulated active sites activated N 2 and CO 2 and accelerated C─N coupling. Under ambient conditions and a 40‐mT magnetic field, ZIF‐67@MIL‐101(Fe) achieved a urea yield as high as 147.28 µmol g −1 h −1 . Mechanism to the enhancement along with reaction pathways were clarified via experimental and simulation results. Practical applicability was confirmed using simulated flue gas, and the obtained urea solution could cultivate wheat seedlings. Overall, this work proposed a magnetic field‐enhanced photocatalytic urea production strategy, offering a universal approach for efficient N 2 activation toward urea and other nitrogen‐containing chemicals.