Cu Electrodeposited Catalysts for a Sustainable Electrochemical Reaction of Nitrate with Ammonia

Electrochemical nitrogen reduction to ammonia (NRR) is a green alternative to the Haber–Bosch process. This reaction is carried out at room temperature and pressure but has low efficiency due to the difficulties associated with breaking the nitrogen triple bond. It is possible to replace the traditional reaction with a nitrate reduction reaction (NO₃RR). In addition, achieving electrochemical nitrate reduction (NO₃⁻) to ammonia (NH₃) is an urgent and important task from the point of view of economics and environmental protection. The unique electronic structure and large reserves of transition metals have led to transition metal-based catalysts being widely studied in the field of the electrochemical conversion of NO₃⁻ to NH₃. Copper-based catalysts have a special electronic structure and exhibit the highest activity and selectivity among single-component metal catalysts for the NO₃RR electrochemical reaction. The unique electronic configuration of copper on the surface promotes adsorption and electron transfer between nitrate ions, which can effectively inhibit the HER (hydrogen evolution reaction) and promote the initial conversion of NO₃⁻ to NH₃. In this study, the catalytic efficiency of copper electrodeposited catalysts in the NO₃RR reaction was studied. The conversion of NO₃⁻ to NH₃ involves a complex transfer of eight electrons and many intermediates. The reaction was carried out at a controlled potential, which was previously established using the method of linear voltammetry. The catalysts were represented by copper and graphite substrates with electrodeposited copper particles on the surface. It was shown that the catalysts have a certain level of catalytic activity. Calculations of Faradaic efficiency showed values of up to 29%. All the electrocatalysts were characterized by SEM, EDX, and other modern methods. This study is a composite, but at the same time complete, part of other work focused on the synthesis of new catalysts for NO₃RR and NRR.