Towards continuous ammonia electro-oxidation reaction on Pt catalysts with weakened adsorption of atomic nitrogen

One of the key challenges for ammonia-fed anion exchange membrane fuel cells is to the ammonia electro-oxidation reaction (AEOR) at anode, which has sluggish kinetics and generates atomic nitrogen (N ads ) poisoning the Pt catalyst. In this study, a comparative study on Pt/Ta 3 N 5 , Pt/Ta 2 O 5 , Pt/carbon black, and Pt plate are conducted in order to clarify the promoting effect of the support materials for Pt catalysts. X-ray photoelectron spectroscopy analysis and density functional theory calculations reveal that the support materials significantly affect the electron condition of the Pt, resulting in the tuned adsorption energy of N ads on Pt surface. The electrochemical analysis demonstrates that the weakened adsorption of N ads lowers the coverage of N ads on Pt surface, resulting in the enhanced performance and stability of Pt catalysts for AEOR. In particular, Pt/Ta 3 N 5 catalyst exhibits a current density of 5.92 mA cm −2 of AEOR at −0.34 V vs. SCE, which is higher than that of Pt/Ta 2 O 5 (2.56 mA cm −2 , −0.35 V vs. SCE) and Pt/C (4.45 mA cm −2 , −0.26 V vs. SCE). The achievements in this study demonstrate the importance of controlling the type of supports for the development of an active electrocatalyst for continuous AEOR.