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Simultaneous CO2 Reduction and Dye (Crystal Violet) Removal Electrochemically on Sn and Zn Electrocatalysts Using Co3O4 Anode

Yadav, V. S. K., Purkait, M. K.
Energy & Fuels 2016 v.30 no.4 pp. 3340-3346
anodes, carbon dioxide, cathodes, coatings, cobalt oxide, color, electric power, electrochemistry, electrolytes, formic acid, gentian violet, graphene, oxidation, potassium bicarbonate, sodium bicarbonate, tin, zinc
The simultaneous reduction of CO₂ to product electrochemically (RCPE) was studied on Sn and Zn electrocatalysts and oxidation of dye (crystal violet (CV)) at Co₃O₄ electrocatalyst. The electrodes for anode and cathode were prepared by coating the electrocatalysts on the graphite surface. The experimental studies were done in aqueous 0.5 M NaHCO₃ and KHCO₃ electrolyte solutions with CV (10 ppm) at different applied voltages (2–3.8 V). The results in forming product and CV dye removal were shown in time intervals of 5, 10, 15, 20, and 25 min, respectively. However, HCOOH was the only reduced product formed from RCPE, along with removal of CV observed for the applied experimental conditions. High Faradaic efficiency of 45.33% for HCOOH at Zn electrocatalyst in KHCO₃ solution was observed in reaction time of 5 min. Maximum dye removals for Sn and Zn electrocatalyst are reported to be 64.3 and 61% in NaHCO₃ electrolyte solution, and similarly dye removals of 71.5 and 60.9% were obtained in KHCO₃ electrolyte at 2.8 V for 25 min. It was observed that as applied voltages increases Faradaic efficiency decreases and CV removal increases. These results reveal the solution for simultaneous CO₂ reduction to HCOOH and purification of colored water. The proposed process may assist to develop new ideas in order to improve the simultaneous RCPE with dye removal.