Nuclear Magnetic Resonance Methods for Investigation of Electrochemical Phenomena in Direct Alcohol Fuel Cells

Nuclear magnetic resonance (NMR) spectroscopy has been one of the essential methods to identify chemicals and characterize dynamics and structure of them. Utilizing the advantages of NMR spectroscopy we have investigated electrochemical phenomena occurring in direct alcohol fuel cells (DAFCs) and identified electronic, chemical and structural changes of FC components during each FC assembly and operation process. With the device that we have developed, the functional difference of anode catalysts such as Pt and PtRu could be in situ detected. Liquid state ¹³C NMR spectroscopy was utilized to analyze the anode exhaust of DAFC and to correlate quantitatively the amount of electrical current generated to the quantities of each chemical product. Magic angle spinning (MAS) NMR spectroscopy and the membrane electrode assembly (MEA) composed of triple-polymer electrolyte membrane layers were employed for the study of methanol crossover and methanol reaction intermediates in a DAFC.

   Our work demonstrates that 1) in situ NMR observation of real DAFCs is possible, 2) the in situ and ex situ NMR techniques can be used for the investigation of alcohol oxidation reaction mechanisms, and 3) the electronic, chemical and structural changes of FC components during each FC assembly and operation process can be studied by various NMR methods.