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Electrochemical synthesis of ammonia was investigated using a cobalt-free La0.6Sr0.4Fe0.8Cu0.2O3-δ-Ce0.8Sm0.2O2-δ (LSFCu-SDC) composite cathode and SDC-ternary carbonate composite electrolyte. La0.6Sr0.4Fe0.8Cu0.2O3-δ and Ce0.8Sm0.2O2-δ were prepared via combined EDTA-citrate complexing sol–gel and glycine nitrate processes, respectively, and characterised by X-ray diffraction (XRD). Ammonia was successfully synthesised from wet hydrogen and dry nitrogen under atmospheric pressure using Ni-SDC, SDC-carbonate and LSFCu-SDC composites as anode, electrolyte and cathode respectively. Ammonia formation was observed at 400, 425, 450 and 475 °C and the maximum rate of ammonia production was found to be 5.39 × 10−9 mol s−1 cm−2 at 450 °C and 0.8 V. The AC impedance measurements were recorded before and after the ammonia synthesis in the range of temperature 400–475 °C. The formation of ammonia at the N2 side together with stable current at 450 °C under constant voltage demonstrates that SDC-(Li/Na/K)2CO3 composite electrolyte exhibits significant proton conduction at a temperature around 450 °C.

Electrochemical synthesis of ammonia based on carbonate electrolyte is presented in this paper. Spinel oxide CoFe 2 O 4 was synthesised via a co-precipitation method and characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ammonia was successfully synthesised from hydrogen and nitrogen under atmospheric pressure using CoFe 2 O 4 as catalyst (primary particle size 10–20 nm) together with silver at the cathode, Ag–Pd at the anode and carbonate-LiAlO 2 composite as electrolyte respectively. Ammonia formation was observed at 400, 425 and 450 °C and the maximum rate of ammonia production was found to be 2.32 × 10 −10 mol s −1 cm −2 at 400 °C and 0.8 V. The AC impedance measurements were recorded before and after the ammonia synthesis at 400, 425 and 450 °C. The electrolytic cell during the ammonia synthesis process was more stable at 450 °C and 0.8 V over a period of 2 h. This experiment also indicates that the carbonate-LiAlO 2 composite electrolyte exhibits proton conduction.