Regulating MoS2 edge site for photocatalytic nitrogen fixation: A theoretical and experimental study

Abstract

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.