Hydrogen-assisted activation of N2 molecules on atomic steps of ZnSe nanorods

Electrochemical reduction reaction of nitrogen (NRR) offers a promising pathway to produce ammonia (NH3) from renewable energy. However, the development of such process has been hindered by the chemical inertness of N-2. It is recently proposed that hydrogen species formed on the surface of electrocatalysts can greatly enhance NRR. However, there is still a lack of atomic-level connection between the hydrogenation behavior of electrocatalysts and their NRR performance. Here, we report an atomistic understanding of the hydrogenation behavior of a highly twinned ZnSe (T-ZnSe) nanorod with a large density of surface atomic steps and the activation of N-2 molecules adsorbed on its surface. Our theoretical calculations and in situ infrared spectroscopic characterizations suggest that the atomic steps are essential for the hydrogenation of T-ZnSe, which greatly reduces its work function and efficiently activates adsorbed N-2 molecules. Moreover, the liquid-like and free water over T-ZnSe promotes its hydrogenation. As a result, T-ZnSe nanorods exhibit significantly enhanced Faradaic efficiency and NH3 production rate compared with the pristine ZnSe nanorod. This work paves a promising way for engineering electrocatalysts for green and sustainable NH3 production.

Automated summary

Electrochemical reduction reaction of nitrogen (NRR) is a promising way to produce ammonia (NH3) from renewable energy. However, the chemical inertness of N-2 has hindered the development of this process. Recent research suggests that hydrogen species formed on the surface of electrocatalysts can enhance NRR. However, the atomic-level connection between the hydrogenation behavior of electrocatalysts and NRR performance is still lacking. This study provides an understanding of the hydrogenation behavior of a highly twinned ZnSe nanorod and the activation of N-2 molecules on its surface, paving the way for engineering electrocatalysts for green and sustainable NH3 production.