• • The GM/UiO-66 ternary heterojunction achieves an NH3 generation rate of 25.1 μmol g−1 h−1 under simulated solar illumination, which is 1.9 times higher than pristine UiO-66 (13.5 μmol g−1 h−1), demonstrating a substantial enhancement in photocatalytic nitrogen fixation efficiency.
• • The internal electric field at the heterointerface drives anisotropic migration of photogenerated charges, leading to rapid separation of electron–hole pairs and suppression of interfacial recombination, which is critical for improving quantum efficiency in photocatalytic systems.
• • The intrinsic defect structure of GO provides key sites for N2 adsorption and activation, while π–π interactions between GO and UiO-66 accelerate electron transfer, highlighting the role of defect engineering and interfacial interactions in enhancing catalytic activity.
• • The Schottky junction between UiO-66 and MXene promotes hole transfer, and the introduction of GO and MXene enhances visible-light absorption of UiO-66, collectively contributing to the improved photocatalytic performance under solar irradiation.