Photocatalytic nitrogen fixation has attracted extensive attention in recent years. Studies have shown that catalytic materials with O, N and other defects can effectively reduce the bond energy of NN triple bond when N₂ is adsorbed on the defects. As an outstanding non-metallic catalyst, g-C₃N₄ has been widely studied in the field of photocatalytic catalysis, and the nitrogen-defected C₃N₄ shows promoted photocatalytic activity. Herein, nano-size MOF-74 particles (<20 nm) was dispersed on nitrogen-defected C₃N₄ thin film (∼4 nm) via a simple sol–gel method. The combination of Nano-MOF and defected film C₃N₄ could effectively improve the photocatalytic activity of nitrogen fixation through Z-scheme mechanism compared with pure defected film C₃N₄.