Enhanced onset potential NiMn-decorated activated carbon as effective and applicable anode in urea fuel cells

Abstract

Basically, to be used as an anode in the air-cathode fuel cells, the onset potential of the introduced material should be lower than the ORR potential. Unfortunately, especially in the field of urea fuel cells, most of the reported electrocatalysts do not own this very important feature. NiMn nanoparticles-decorated activated carbon is introduced as strongly enhanced onset potential and highly effective electrocatalyst for urea oxidation. For bimetallic nanoparticles having 10wt% Mn, the corresponding onset potential is ˗85mV (vs. Ag/AgCl) with a corresponding current density of 130mA·cm−2. However, other contents (0, 20 and 30wt%) of Mn do not show this high improvement in the electrocatalytic activities. Decoration of the activated carbon can be achieved by hydrothermal treatment of the metals acetates/activated carbon aqueous suspension followed by fast cooling to perform sudden transformation of the subcritical water to a normal one. Later on, the powder is sintered in argon atmosphere at 850°C. Fortunately, the characterizations confirmed that the modified activated carbon is decorated by pristine NiMn nanoparticles rather than the expected oxides.