2353
Manganese Oxide/Reduced Graphene Oxide Nanocomposite for High-Efficient Electrocatalyst Towards Oxygen Reduction Reaction

Wednesday, 16 May 2018
Ballroom 6ABC (Washington State Convention Center)
S. Kosasang, N. Ma, N. Phattharasupakun, J. Wutthiprom, J. Limtrakul, and M. Sawangphruk (Vidyasirimedhi Institute of Science and Technology)
The sluggish kinetics of oxygen reduction reaction (ORR) is a critical challenge for metal-air batteries and fuel cells. To increase the reaction rate, the high-efficient electrocatalysts are needed. Among various catalysts, platinum and its alloys are investigated as the best catalyst for the ORR. However, the Pt-based catalysts suffer from many disadvantages, including excessive cost, scarcity, and poor stability. In this work, layered manganese oxides, Li-birnessite, Na-birnessite, K-birnessite and their composites with graphene aerogel were used as the ORR catalysts. The ORR catalytic activity of these materials has been studied using rotating disk electrode (RDE) in O2-saturated and Ar-saturated KOH solution. The linear sweep voltammogram (LSV) curves at scan rate of 10 mVs-1 show that the Li-birnessite/graphene aerogel provided the best catalytic performance with an onset potential of 0.99 V (V vs. RHE), half wave potential of 0.66 V (V vs. RHE), limiting current density of 5.60 mA cm-1 (at a rotation rate of 1600 rpm), and Tafel slope of 104.3 mV dec-1, which is comparable to the Pt catalyst. Moreover, the electron transfer number per oxygen molecule (n) calculated by Koutechy–Levich (K–L) equation is ~ 4, indicating a 4-electron pathway for ORR and suggesting the Li-birnessite manganese oxide coated on graphene aerogel as a high-efficient ORR catalyst.