Directed charge transfer over GM/UiO-66 ternary heterojunction for enhanced photocatalytic nitrogen fixation
The efficient conversion of dinitrogen (N2) to ammonia (NH3) under mild conditions remains a critical challenge for sustainable nitrogen fixation. This study reports a rationally designed ternary heterojunction, GO/MXene/UiO-66 (GM/UiO-66), which achieves directed charge transfer for enhanced photocatalytic nitrogen fixation. 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. The intrinsic defect structure of graphene oxide (GO) provides active sites for N2 adsorption and activation, while π–π interactions between GO and UiO-66 accelerate electron transfer. Additionally, the Schottky junction between UiO-66 and MXene facilitates hole (h+) transfer. The incorporation of GO and MXene extends visible-light absorption of UiO-66. Under simulated solar illumination, GM/UiO-66 exhibits an NH3 generation rate of 25.1 μmol g−1 h−1, which is 1.9 times higher than that of pristine UiO-66 (13.5 μmol g−1 h−1). This work presents a novel strategy for designing ternary heterojunction composites that optimize charge transfer and significantly improve photocatalytic performance.