Heterostructured Co/CoO anchored on N-doped carbon nanotubes as a highly efficient electrocatalyst for nitrate reduction to ammonia.

The electrochemical reduction of nitrate (NO) to ammonia (NH) has emerged as an attractive approach for selectively reducing NO to highly value-added NH and removing NO pollutants simultaneously. In this work, a heterostructured Co/CoO electrocatalyst anchored on N-doped carbon nanotubes was prepared and applied for the NO reduction towards NH under alkaline conditions. The catalyst achieves outstanding performance with up to 67% NH faradaic efficiency at -1.2 V Hg/HgO and 8.319 mg h mg yield at -1.7 V Hg/HgO. In addition, it also exhibits good long-term stability. N isotopic labelling experiments prove that the yielded NH is derived from NO species. electrochemical Raman spectra revealed that the structure of the as-prepared catalyst showed outstanding stability and identified possible intermediates during the electrocatalytic NO reduction reaction (NORR).