Cu-Based Atomic Catalysts for the Electrochemical Hydrogenation of Nitrate to Ammonia

Ammonia is an essential industrial feedstock, but conventional synthesis processes, Haber-Bosch process, emit significant greenhouse gases. Electrochemical ammonia synthesis offers a promising alternative, enabling ammonia production without harmful pollutants. Recently, electrochemical nitrate reduction has attracted considerable attention for ammonia synthesis due to its high selectivity. Achieving efficient ammonia synthesis requires active and selective catalysts, and single-atom catalysts have shown great promise owing to their tunable chemical and geometric active sites. However, challenges remain, including the need to enhance active surface area and suppress competing hydrogen evolution reactions. This minireview summarizes recent advances in the design strategies of Cu-based single-atom catalysts, highlighting their advantages and performance in electrochemical nitrate reduction. Special emphasis is placed on the relationship between local composition/atomic structure and electrochemical nitrogen reduction performance by studying their local atomic coordination such as Cu-N4, Cu-NxO, CuM-Nx, and Cu embedded metal oxides. The review concludes by emphasizing the importance of further research to optimize Cu-based single-atom catalysts for efficient and sustainable ammonia production.