Enhancement of nitrate electroreduction using BDD anode and metal modified carbon fiber cathode

•Cu/CF and Ag/CF composites were produced and characterized.•The amount of metal deposits depends of the functional groups on the CF surface.•The nitrate reduction rate was very fast when the nitrite formation was high.•The best performance of Cu/CF1000 cathode and BDD anode to reduce nitrate.

Silver and copper were electrodeposited on carbon fiber (CF) with heat treatment temperatures of 1000 and 2000 °C. Cu/CF1000 and Ag/CF1000 presented more uniform particles with higher densities than those for CF2000. This behavior was attributed to electrostatic force between Cu2+/Ag+ and CO functional group present on CF1000 surface. Nitrate electroreduction was carried out using Ag/CF or Cu/CF cathode and BDD anode. The rate-determining step of nitrate reduction was its transformation into nitrite ions. The best performance for electrochemical nitrate reduction was achieved using Cu/CF1000 resulting in 100% of nitrate reduction not to mention its low by-product formation.