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 N2 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 N2 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.