Journal of Power Sources, Vol.267, 33-38, 2014
Microspheres assembled by KMn8O16 nanorods and their catalytic oxygen reduction activity in direct methanol fuel cells
Microspheres assembled using cryptomelane-type KMn8O16 nanorods are synthesized via a facile template-free, single-step hydrothermal technique. The synthesized KMn8O16 generates nanorods 10 -20 nm in diameter and approximately 300-1000 nm long. The rods self-assemble to form microspheres of 2-6 mu m in diameters. The electron transfer number for KMn8O16 during the ORR is approximately 3.98 at 0.5 V vs. Hg/HgO, and the H2O2 percentage is 0.66%. Moreover, a direct methanol fuel cell (DMFC) is built using KMn8O16 as cathodic catalyst, PtRu/C alloy as the anodic catalyst and a polymer fiber membrane (PFM) instead of a conventional polymer electrolyte membrane (PEM). The peak power densities (43.3 mW cm(-2) and 153.9 mW cm(-2)) have been achieved at 25 degrees C and 70 degrees C, respectively. KMn8O16 shows good electrocatalytic activity and stability during oxygen reduction in alkaline solutions and demonstrates tolerance toward methanol poisoning. (C) 2014 Elsevier B.V. All rights reserved.