Journal of Applied Electrochemistry, Vol.44, No.7, 857-866, 2014
Anodic oxidation of butan-1-ol on Pd and Pt electrodes in alkaline medium
Pure Pd is investigated as electro-catalyst for oxidation of butan-1-ol in aqueous NaOH solution and compared with the conventional catalyst, pure Pt. The steady-state anodic current density increases on increasing the potential up to -52 and -3 mV for Pt and Pd, respectively, and it reveals that Pd is a better electro-catalyst than Pt above -0.18 V versus MMO [Hg/HgO/OH-(0.1 M) having reversible electrode potential of 0.1 V vs. NHE]. Multiple scan cyclic voltammetry also reveals faster poisoning of Pt than Pd electrode. The Tafel slope for Pd (0.511 V dec(-1)) is lower than Pt (2.30 V dec(-1)) where as poisoning potential and current density of the former are greater than Pt indicating a relatively higher catalytic activity of Pd electrode. The FTIR study reveals the presence of aldehyde group in the products obtained with Pt unlike Pd electrode indicating different mechanistic pathways followed by them. With increase of potential in the range -200 to 300 mV, the order with respect to butan-1-ol gradually decreases for Pt due to poisoning in the process of formation of complete oxidation product, CO3 (2-), but increases for Pd due to faster removal of adsorbed intermediates with the formation of mainly butyrate. In this study, different mechanisms are proposed for Pt and Pd which conform to the experimental results.
Keywords:Butan-1-ol electro-oxidation;Catalytic activity of Pt and Pd;Order;FTIR study of products;Mechanism of oxidation