SnO2-modified Pt electrocatalysts for ammonia–fueled anion exchange membrane fuel cells

• The ammonia oxidation over SnO2–modified Pt catalysts was evaluated in alkaline media.
• SnO2 activated the dehydrogenation reaction of ammonia over Pt.
• SnO2 was stable under 1000 potential cycles (0.05–0.9 V vs. RHE) in alkaline media.

The electrochemical oxidation of ammonia over two types of SnO2-modified Pt (C–Pt/SnO2, SnO2–Pt/C) and Pt/C electrocatalysts was evaluated in alkaline aqueous solutions. Linear sweep voltammograms (LSVs) and chronoamperograms (CAs) were obtained in a 1 M KOH solution with 0.1 M NH3. The ammonia oxidation current achieved during the LSVs was in the order C–Pt/SnO2 > SnO2–Pt/C > Pt/C. In addition, the apparent activation energies for ammonia oxidation calculated from the CAs for C–Pt/SnO2, SnO2–Pt/C, and Pt/C at various temperatures were 52, 58, and 67 kJ mol−1, respectively. These results indicated that SnO2 activated the dehydrogenation of ammonia over Pt. Moreover, the I–V characteristics of an ammonia-fueled anion exchange membrane fuel cell with the SnO2–Pt/C anode clearly achieved a higher performance than with the Pt/C anode.