Preparation and characterization of nano structured Pt-MOx/C for oxygen reduction reaction in acidic medium

Abstract

Pt-MOx/Ca cheapand (M =efficient Ti, Ce orelectrocatalysts Zr) electrocatalystsfor oxygen was preparedreduction for thereaction purpose(ORR) of developingusing a mixture of ethylene glycol and sodium borohydride (EG + NaBH4) as areducing agent. Pt/C was studied for estimation of metal oxides effect.Pt-CeO2/C-1 was prepared through single reducing agent ethylene glycol for studying the effect of changing the reducing agent on the activity of electrocatalysts toward ORR and for studying ORR kinetics. The electrocatalytic activity of the prepared electrocatalysts towards (ORR) was evaluated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) on a rotating disc electrode (RDE). Pt-ZrO2 /C shows the best activity towards ORR among the studied electrocatalysts; the oxygen reduction current density for it is about 5 times; (5.84 mAcm-2) as that of Pt/C (1.26 mAcm-2). Pt-CeO2/C showed better ORR activity (2.24 mAcm-2) than Pt-CeO2/C-1(1.58 mAcm-2) indicating the great effect of changing the reducing agent not only on the electrocatalyst behavior towards ORR but also its particle size and the metal content of the resultant electrocatalysts. Oxygen reduction mechanism for Pt-CeO2/C and Pt-CeO2/C-1 was evaluated using through Koutecky-Levich, they showed first-order kinetics with ORR not controlled solely by diffusion. XRD, EDX and TEM analyses were used to characterize the prepared electrocatalyst.