Ni-coated graphite felt modified with Ag nanoparticles: A new electrode material for electro-reductive dechlorination

Reductive removal of the organochlorine herbicide alachlor on Ni-coated graphite felt modified with Ag nanoparticles (Ag/Ni@GF) was studied. Ag/Ni@GF was prepared by spontaneous deposition of silver onto Ni-coated graphite felt (Ni@GF), which was previously obtained by electrodeposition of Ni onto graphite felt (GF). Interestingly, Ag/Ni@GF exhibited a high specific surface area of 26 m2 g-1 determined by the Brunauer-Emmett-Teller (BET) method and a high Ag loading of 13.7 mg cm-3 as shown by electrochemical analyses. Alachlor (50 mg L-1 in 0.05 M NaOH) was successfully reduced at -0.9 V vs. mercury-mercurous sulfate electrode with 96% conversion efficiency and a current efficiency up to 33%. The main by-product was its dechlorinated derivative, deschloroalachlor, obtained with 76% yield. Surface-enhanced Raman scattering (SERS) showed that PVP, necessary to control Ag nanoparticles deposition, does not affect the catalytic activity of Ag. Ag/Ni@GF electrodes could be used several times, highlighting their good stability.