Fig. 3

Current density (a) and power density (b) of the vapor-fed FC versus voltage, for a range of ethanol partial pressures. Three runs were done for the 1.7 mmHg ethanol data, and the standard deviation of the data is shown in the error bars. As the partial pressure increased, the peak power point shifted to lower voltages. Maximum power density of 2 mW/cm² was obtained for 1.7 mmHg (3% ethanol in solution), at 280 mV. Lines are polynomial fits to guide the eye