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

The creation of active sites on semiconductor catalysts for the adsorption of N-2 and dissociation of nonpolar N equivalent to N bond is a key issue for photocatalytic N-2 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 N-2 adsorption moderated. Furthermore, the injection of electrons into the N equivalent to N bond is promoted, leading to lowering of energy barrier for N-2 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 mu mol g(-1)h(-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.

Automated summary

The study revealed that the active sites on MoS2 for N-2 adsorption and dissociation are mainly located on Mo rather than S edge, and Mn doping can enhance the exposure of Mo edge sites. Injection of electrons promotes the reduction of N-2, leading to a higher ammonia production rate in Mn-modified MoS2 photocatalysts without sacrificial agent.