▎ 摘　　要

For the development of a highly active and energy-effective electro-Fenton process, highly efficient 2e(-)pathway oxygen reduction reaction electrocatalytic materials forin situelectrochemical synthesis of H(2)O(2)are extremely important. A novel nitrogen-doped graphene nanosheets (N-Gns) is prepared, characterized, investigated for the oxygen reduction reaction, and employed for highly toxic chlorophenoxy acid herbicides degradation in water. Herein, we report novel nitrogen-doped graphene nano sheets (N-Gns), which exhibit superior electrocatalytic activity and stability for oxygen reduction reaction (ORR) in acidic medium, which is utilized for Electro Fenton's reaction. The effects of operating parameters such as applied current, pH of the solution, inter-electrode distance, ferrous ion concentration, oxygen flow rate and initial concentration of herbicides were investigated. The herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D), 2-(2,4- dichlorophenoxy) propanoic acid (2,4-DP), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2,4,5-Trichlorophenoxyacetic acid (2,4,5-T), 2-(2-methyl-4-chlorophenoxy) propionic acid (MCPP) were degraded by electro-Fenton process. All the herbicides exhibited the total organic carbon removal efficiency greater than 95 % within 240 minutes. The four various places of Madurai district, Tamil Nadu, India, real water samples were collected and spiked with standard 2,4-D solution and its degradation was studied by as-prepared electrodes. The degradation efficiency was greater than 95 % with 300 min. It is comparatively less high than synthetic waste water (herbicides). It is due to the presence of natural organic matter in the real water samples. Hence the herbicides 2,4-D, 2,4-DP, 2,4,5-T, MCPA and MCPP were successfully removed by the as-synthesizedN doped graphene nano sheets (N-Gns). The as-prepared (N-Gns) exhibits high activity and desirable stabilityand represents a potential candidate material as electro-Fenton cathode for energy-effective water treatment.