Sulfur vacancy MoS2 for electrocatalytic reduction of nitrate to ammonia with enhanced selectivity

Abstract

As an important raw material, ammonia consumes a significant amount of the world’s energy. The electrocatalytic reduction of nitrate to ammonia provides a new way to generate NH3 from waste water under benign conditions. However, NO3− conversion toward N2 and H2 evolution reaction (HER) competition limit the development of nitrate reduction to ammonia. In this study, we synthesized MoS2 with sulfur vacancies (SVs) using a one-step hydrothermal method, and we used the SVs to utilize the H* from the side reaction HER and accelerate the process of *N to NH3. MoS2 with SVs exhibits higher ammonia synthesis performance and faradaic efficiency (FE) than that of MoS2, with ammonia yield enhancing from 76.67 μg h−1 mgcat.−1 to 111.33 μg h−1 mgcat.−1 and FE expanding from 44.62 % to 78.04 % at − 0.6 V vs. RHE at ambient conditions. Calculations using density functional theory discovered that the presence of SVs effectively lowered the energy barrier in the potential-determining step for nitrate reduction, and H* couples with nearby *N at Mo sites promote activity. This research enhances our knowledge of how to handle the content of MoS2 with SVs when preparing monolayered MoS2 with special catalytic properties.