Self-supported polypyrrole flexible electrodes for electrochemical reduction of nitrite

Abstract

The efficiency of an electrochemical oxidation/reduction process strongly depends on the working electrode's surface area to volume ratio. By making electrodes flexible and employing different configurations such as roll-to-roll membrane, the surface area to volume ratio can be enhanced, therefore improving the overall efficiency of electrochemical processes. Conductive polymers emerge as a new framework to enable alternative electrochemical water treatment cell configurations. Self-standing polypyrrole flexible electrodes were synthesized by electropolymerization and evaluated on the treatment of an oxyanion pollutant: nitrite. Mechanical characterization through stress-strain curves and bending tests demonstrated high electrode resilience that sustained over 1000 bending cycles without impacting mechanical integrity or electrocatalytic responses. The electrocatalytic response towards nitrite reduction was assessed under linear scan voltammetry (LSV) and removal performance evaluated under potentiostatic conditions reaching 79% abatement of initial concentrations of nitrite of 15 mg/L [NO₂^--N]. Self-standing flexible electrodes appear as a novel framework to enable modular compact water treatment unit designs that maximize the electrode area/volume ratio and substitute expensive platinum group metal (PGMs) electrocatalysts.

Keywords: Conductive polymers; Electrochemical water treatment; Flexible electrodes; Functional materials; Nitrite reduction.