Electrocatalytic reduction of nitrate by carbon encapsulated Cu-Fe electroactive nanocatalysts on Ni foam.

[Display omitted] • A cheap and binderless CuFe NPs@N C/NF electrocatalyst was prepared. • Electrode with Cu/Fe molar ratio of 1:2 exhibited the highest NO 3 – removal. • N 2 selectivity of the CuFe NPs@N C/NF cathode electrochemical system reached 94.0%. • CuFe NPs@N C/NF had long-term durability for NO 3 – conversion. • The mechanism of electrochemical denitrification on CuFe NPs@N C/NF was proposed. Electrocatalytic denitrification is an attractive and effective method for complete elimination of nitrate (NO 3 –). However, its application is limited by the activity and stability of the electrocatalyst. In this work, a novel bimetallic electrode was synthesized, in which N-doped graphitized carbon sealed with Cu and Fe nanoparticles and immobilized them on nickel foam (CuFe NPs@N C/NF) without any chemical binder. The immobilized Cu-Fe nanoparticles not only facilitated the adsorption of the reactant but also enhanced the electron transfer between the cathode and NO 3 –, thus promoting the electrochemical reduction of NO 3 –. Therefore, the as-prepared electrode exhibited enhanced electrocatalytic activity for NO 3 – reduction. The composite electrode with the Cu/Fe molar ratio of 1:2 achieved the highest NO 3 – removal (79.4 %) and the lowest energy consumption (0.0023 kW h mg−1). Furthermore, the composite electrode had a robust NO 3 – removal capacity under various conditions. Benefitting from the electrochlorination on the anode, this electrochemical system achieved nitrogen (N 2) selectivity of 94.0 %. Moreover, CuFe NPs@N C/NF exhibited good stability after 15 cycles, which should be attributed to the graphitized carbon layer. This study confirmed that CuFe NPs@N C/NF electrode is a promising and inexpensive electrode with long-term stability for electrocatalytic denitrification. [ABSTRACT FROM AUTHOR]