Electrochemical reduction of nitrate to NH3 is a very promising alternative reaction to the Haber-Bosch process, and it is necessary to develop the efficient electrocatalysts. In this study, a particle-support mode Co3O4 catalyst was synthesized with ZIF-67 as the precursor, and then dispersed on MoS2 nanoflowers by hydrothermal method. The Co3O4 is anchored to MoS2 by forming Co-S coordination bond. Furthermore, the particle-supported Co3O4 exhibits better performance than Co3O4 alone, as is manifested by higher Faradaic efficiencies and NH3 yield rate at − 0.64 V (52.69% vs 32.03%; 4539.61 μg h−1 mg−1cat vs 2048.63 μg h−1 mg−1cat), lower energy barriers (0.96 eV vs 1.19 eV), and better electronic conductivity (Bandwidth: 0.581 eV vs 0.613 eV). In addition, this research provides an effective solution to solve the aggregation problem of metal oxide nanoparticles.