Electrocatalytic Reduction Of Organic Pollutants In Water By Electro-Deposited Cu-Based Catalysts Modified Electrodes

Nitrobenzene is a typical nitro-aromatic pollutant, while atrazine is a typical chlorinated organic pollutant, both of which are widely present in water environment. Electrocatalytic reduction technology has received increasing interests for the degradation of organic pollutants due to its environmental friendliness, easily-controlled process and cost-effectiveness. In this work, with nitrobenzene and atrazine as target pollutants, electrode materials with a high electrocatalytic activity, great stability and low cost for their electrocatalytic reduction degradation were prepared, and then the major influencing factors on the electrocatalytic reduction performance were studied, and the reduction mechanisms were also elucidated.Cu catalysts with different morphologies were fabricated on Ti plate using a facile electrodepositon method via tuning the applied voltage. The dendritic nano-structured Cu catalyst obtained at higher applied voltages exhibited an excellent efficiency and selectivity towards the reduction of nitrobenzene to aniline, and the electroreduction of nitrobenzene on Cu/Ti electrode followed pseudo-first-order kinetics. Effects of the working potential and initial nitrobenzene concentration on the selective reduction of nitrobenzene to aniline using Cu/Ti electrode were investigated, and process parameters were optimized. A high rate constant of0.0251min-1and97.1%aniline selectivity were achieved in150min when the working potential was applied at-0.9V and the initial concentration of nitrobenzene was16mg-L-1. The fabricated Cu/Ti electrode exhibited good stability for the selective electrocatalytic reduction of nitrobenzene to aniline in the ten consecutive sequence degradation experiments.Cu@Pd bimetallic core-shell catalyst loaded on Ti plate was prepared via combined electrodeposition and galvanic replacement deposition for electrocatalytic hydrodechlorination of atrazine. The obtained bimetallic catalyst with uniformly dispersed Pd nanoparticles possessed a large electrochemically active surface area of572cm2. Compared with individual Pd/Ti or Cu/Ti cathodes, Cu@Pd/Ti cathode exhibited a higher electrocatalytic efficiency towards atrazine reduction, and achieved up to91.5%within120min under a current density of1mA·cm-2. The electrocatalytic reduction of atrazine on the Cu@Pd/Ti electrode followed pseudo-first-order kinetics with a rate constant of0.0214min-1under the optimal reaction conditions. In the five consecutive electrolysis experiments, the stability of Cu@Pd/Ti electrode was maintained. In the electroreduction process, atrazine was selectively transformed to dechlorinated atrazine via both direct and indirect pathways. Current density was found to have a critical influence on the atrazine reduction due to the competitive hydrogen evolution reaction at a higher current density.