Electrochemically reductive dechlorination of 3,6-dichloropicolinic acid on a palladium/nitrogen-doped carbon/nickel foam electrode

Abstract

Pd was electro-deposited on Ni foam using nitrogen-doped carbon as an inter-layer (EDPd/CNx/Ni). The as-prepared material was employed as the cathode for the electrochemical dechlorination of 3,6-dichloropicolinic acid (3,6-D) in an aqueous solution. When compared to the electrodes that direct the electrodeposition or chemical deposition of Pd on Ni foam, EDPd/CNx/Ni exhibited higher activity and selectivity during the electrocatalytic hydrogenation of 3,6-D to form the intermediates 3-chloropicolinic acid and 6-chloropicolinic acid, as well as the final product, 2-picolinic acid. Furthermore, the modified electrode maintained its high dechlorinating activity after continuous operation for three batches. On the basis of physical-chemical characterization and electrochemical measurements, it is proposed that the superior performance of the EDPd/CNx/Ni electrode benefits sufficiently from the accelerated generation of adsorbed hydrogen ([H]ads). The electrodeposition method facilitates the generation of Pd with a higher percentage of exposed {111} facets. The CNx functions as an efficient support for the enlargement of the electrochemically active surface area, the reduction of Pd particle size, and improvement of the Pd dispersion. Moreover, CNx may also act as an electrocatalyst for the water-splitting reaction and favors the stabilization of chemisorbed active hydrogen.