Ammonia is a key raw material for fertiliser production. It has a high hydrogen content and a high gravimetric energy density. Currently, the main ammonia production technique is the Haber-Bosch process, which requires operation at high temperatures and pressures. Ammonia production results in high energy consumption and costs, and new ammonia synthesis processes are needed to reduce the energy required and the carbon footprint. Electrochemical synthesis is a method involving the electro-reduction of nitrogen to ammonia on the surface of an electro-catalyst in the presence of a proton donor. To increase the efficiency of these electrochemical processes, various catalysts have been investigated, such as transition metal complexes and non-precious metal materials. Key aspects in the electrochemical synthesis of ammonia include the design of efficient catalysts, the optimisation of electrode materials and the appropriate composition of electrolytes. The choice of catalyst has an important influence on the selectivity and activity of the reaction, while the electrode material plays a key role in the electron transfer kinetics. In addition, the composition of the electrolyte influences the overall performance and stability of the electrochemical system. There are challenges related to improving the overall energy efficiency, scalability and sustainability of electrochemical cells used in ammonia synthesis.
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