In this work, we have investigated the conductivity, electrochemical window (ECW) and oxygen reduction reaction (ORR) in various bis(trifluoromethanesulfonyl)imide (TFSI)-based room temperature ionic liquids (RTILs). In an attempt to improve ORR activity in RTILs, water and/or dimethyl sulfoxide (DMSO) are added to one TFSI-based RTIL, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (BMP-TFSI), and the effect of additives on its conductivity, ECW and ORR is explored. The results show that as-received TFSI-based ionic liquids (ILs) have a low conductivity due to their large constituent ions. The addition of water and/or DMSO has considerable effect on the conductivity of the IL mixture. The studied TFSI-based RTILs have wide ECWs and the presence of water and/or DMSO causes an apparent narrowing of the observed potential window. For all TFSI-based ILs, the oxygen redox peaks can be assigned to an O2/O2−• one-electron transfer process. By adding water, the O2/O2−• redox potential shifts in a more positive direction in BMP-TFSI; e.g., about 0.27 V more positive in BMP-TFSI with 1 wt% water addition, due to its high acceptor number (AN) and the proton effect. The addition of DMSO also contributes to the improvement in ORR activity in BMP-TFSI through enhanced conductivity and redox reversibility.

Synthesis and characterization of quaternary PtRuIrSn/C electrocatalysts for direct ethanol fuel cells Fatih, K.; Neburchilov, V.; Alzate, V.; Neagu, R.; Wang, H. 195 (2010) [7168][7169][7170][7171][7172][7173][7174][7175] Contents lists available at ScienceDirect /C electrocatalysts were prepared by a known impregnation-reduction (borohydride) method. The microstructure and chemical composition were determined by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The activity of the electrocatalysts for EOR was compared to commercial Pt 67 Ru 33 /C (HISPEC5000) using linear sweep voltammetry (LSV) based on similar Pt loading. The results of this study show that electrocatalyst composition with 10 and 20% Ir (wt.%) exhibit higher electrocatalytic activity than the commercial PtRu electrocatalyst. 10 Sn 30 /C exhibited both a higher performance with a specific power density of 29 mW mg Pt −1 without O 2 backpressure at the cathode and an excellent long-term stability in a DEFC operating at 90 • C. Journal of Power Sources Journal of Power SourcesCrown

Effect of operating parameters and anode diffusion layer on the direct ethanol fuel cell performance Alzate, V.; Fatih, K.; Wang, H. 196 (2011) a b s t r a c t A parametric study was conducted on the performance of direct ethanol fuel cells. The membrane electrode assemblies employed were composed of a Nafion ® 117 membrane, a Pt/C cathode and a PtRu/C anode. The effect of cathode backpressure, cell temperature, ethanol solution flow rate, ethanol concentration, and oxygen flow rate were evaluated by measuring the cell voltage as a function of current density for each set of conditions. The effect of the anode diffusion media was also studied. It was found that the cell performance was enhanced by increasing the cell temperature and the cathode backpressure. On the contrary, the cell performance was virtually independent of oxygen and fuel solution flow rates. Performance variations were encountered only at very low flow rates. The effect of the ethanol concentration on the performance was as expected, mass transport loses observed at low concentrations and kinetic loses at high ethanol concentration due to fuel crossover. The open circuit voltage appeared to be independent of most operating parameters and was only significantly affected by the ethanol concentration. It was also established that the anode diffusion media had an important effect on the cell performance. Journal of Power SourcesCrown