The creation of active sites on semiconductor catalysts for the adsorption of N₂ and dissociation of nonpolar N≡N bond is a key issue for photocatalytic N₂ reduction reaction (PNRR). According to density function theory calculation on MoS₂, the Mo rather than the S edge sites are active, and those on basal planes not. It is disclosed that Mn doping is an effective way to boost the activity of MoS₂ by modifying the edge sites. The Mn-modified MoS₂ has higher exposure of Mo edge sites due to the formation of S vacancies. It is noted that the activity of original Mo edge sites remains unaltered, while the inertness of S edge sites for N₂ adsorption moderated. Furthermore, the injection of electrons into the N≡N bond is promoted, leading to lowering of energy barrier for N₂ reduction. Finally, through a simple hydrothermal method we prepared MoS₂ that is rich in edge sides at the basal plane by Mn doping. High ammonia production rate of up to 213.2 μmol g⁻¹h⁻¹ is achieved, which is 5.3 times that of pristine MoS₂ and superior to most of the reported MoS₂-based photocatalysts in the absence of sacrificial agent.