High‐Loading Ag Single Atoms Anchored on MoS ₂ Nanosheet Aggregates Enable Synergistic Nitrate‐to‐Ammonia Electroconversion

ABSTRACT

Electrocatalytic nitrate reduction (NO ₃ RR) to ammonia (NH ₃ ) offers a sustainable route for coupling nitrate (NO ₃ ⁻ ) remediation with NH ₃ synthesis. However, its efficiency is often limited by the insufficient NO ₃ ⁻ activation, incomplete hydrogenation of nitrogen‐containing intermediates, and the competing hydrogen evolution reaction (HER). Herein, we report a catalyst consisting of Ag single atoms anchored on flower‐like MoS ₂ nanosheet aggregates (Ag‐MoS ₂ NAs) for efficient NO ₃ ⁻ ‐to‐NH ₃ conversion. Ag‐MoS ₂ NAs feature a high loading of isolated Ag sites while preserving atomic dispersion, providing abundant NO ₃ ⁻ activation centers. During NO ₃ ⁻ ‐to‐NH ₃ conversion, Ag sites promote NO ₃ ⁻ adsorption and initial deoxygenation steps, whereas MoS ₂ provides active hydrogen species for the subsequent hydrogenation of nitrogen‐containing intermediates. The integration of these complementary functions enables efficient NO ₃ ⁻ activation and subsequent hydrogenation, thereby enhancing NH ₃ production and achieving a Faradaic efficiency of up to 95%. As a result, the Ag‐MoS ₂ NAs maintain stable operation for over 200 h at current densities exceeding 400 mA cm ⁻² , achieving an NH ₃ yield rate of 30.6 mg h ⁻¹ cm ⁻² . This work demonstrates that integrating NO ₃ ⁻ activation sites with hydrogenation functionalities in a single catalyst can effectively promote NH ₃ production from NO ₃ ⁻ under industrially relevant conditions.