Reduction of nitrite to ammonia on PEDOT–bipyridinium–Fe complex electrodes

• We report a facile method to prepare PEDOT–bipyridinium–Fe electrocatalysts.
• PEDOT–BIPY–Fe electrodes start to reduce nitrite to ammonia at only − 0.4 V.
• 90% faradaic efficiency is achievable at − 0.65 V applied potential.
• Efficient charge transfer is seen between the electrode and nitrite anions.

Various issues still exist for electrochemical nitrite reduction to ammonia especially the significant overpotential and the formation of unwanted side products. In this work, we aim to develop an electrochemical method to facilitate the ammonia production from nitrite under ambient conditions and low overpotentials. Poly(3,4-ethylenedioxythiophene)-5,5′-(dithiophen-2-yl)-2,2′-bipyridine-Fe (PEDOT–BIPY–Fe) electrodes were prepared using a facile vapour phase polymerization method. In-situ electrochemical UV–vis results confirm the presence of the Fe complex in the electrode. The obtained electrodes show good charge transfer between the PEDOT and the Fe complex and was successfully used to reduce nitrite to ammonia. Ammonia was detected when the applied potential was only − 0.4 V (vs Ag/AgCl) and high yield was achieved when − 0.5 V (vs Ag/AgCl) or more negative potentials were applied.

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