Effect and mechanism of PEDOT-Cu/Cu2O on the electrochemical reduction of nitrate with carbon electrodes

Electrochemical nitrate reduction for ammonia nitrogen (NH4+-N) generation is a promising method for resources recycling and relies on cheap and stable electrodes. In this study, carbon plate (CP), carbon felt (CF), and carbon brush (CB) were compared to identify their potential value on electrochemical nitrate reduction. By using the electrodeposition technique, copper-based nanometallic particles (Cu/Cu2O NPs) and poly-3,4-ethylenedioxythiophene (PEDOT) were loaded on the carbon substrates to prepare the (Cu/Cu2O) NPs/PEDOT/(Cu/Cu2O) NPs/CF electrode, which was tested in a single chamber electrolytic cell and subjected to continuous electrolysis of artificial wastewater (25–100 mg L−1 NO3--N) for 12 h. At a current density of 30 mA cm−2, the electrode achieved 97% nitrate removal and 81% NH4+-N selectivity. The synergistic catalytic interaction between Cu/Cu2O NPs and PEDOT improved the electrode reduction activity and NH4+-N selectivity, and had a good H* providing ability as noble metals. This provides a new method for nitrate reduction and NH4+-N recovery. [Display omitted] •Systematic comparison of electrochemical denitrification of three carbon-based materials.•The (Cu/Cu2O) NPs/PEDOT/(Cu/Cu2O) NPs/CF electrode has excellent nitrate removal and NH4+-N selectivity.•A possible electrochemical denitrification mechanism was proposed.