Improved ammonia production using Cu2O@poly-carbazole electrocatalysts in the electrochemical reduction of molecular nitrogen and nitrogen oxoanions

Abstract

In the present study, a Cu₂O@PCz electrode for the nitrogen reduction reaction is proposed; this electrode takes advantage of the catalytic properties of Cu₂O in conjunction with conducting polymers such as polycarbazole (PCz). This combination demonstrates an improvement in the catalytic activity and higher stability of this metal oxide in nitrogen electro-reduction reaction (NRR) and nitrogen oxoanion electro-reduction reaction (NORR) processes under aqueous conditions. On this basis, the material synthesized on FTO (SnO₂ : F), Cu₂O@PCz, exhibits a faradaic efficiency of around 38.83%, together with an NH₃ productivity of 1.83 μg h⁻¹ cm⁻² in NRR type processes, on applying a potential of −0.8 V (V vs. Ag/AgCl). Similarly, in NORR type processes, the material exhibits NH₃ and N₂H₄ productivity. The latter is the most relevant in terms of the yields obtained. Specifically, using nitrite (NO₂⁻), an efficiency of around 77.72% was obtained, together with a formation rate of 37.02 μg h⁻¹ cm⁻² at a potential of −0.8 V (V vs. Ag/AgCl). Although N₂H₄ is a by-product of ammonia formation, this molecule can be considered an intermediate, which broadens the scope of this study for future research into the production of green chemicals. Finally, this research presents promising new routes for the production of NH₃ at room temperature, highlighting the potential of low-cost materials, easy synthesis, and enhanced stability.