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

Abstract

In the present study, a Cu2O@PCz electrode for nitrogen reaction reduction 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 (NRR) and nitrogen oxoanion electro-reduction (NORR) processes in aqueous conditions. On this basis, the material synthesized on FTO (SnO2:F), Cu2O@PCz, exhibits a faradaic efficiency around 38.83%, together with an NH3 productivity of 1.83 µg h-1 cm-2 in NRR type processes, applying a potential of -0.8 V (V vs Ag/AgCl). Similarly, around 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.