Electrochemical Calorimetric Studies of the Cold Fusion Effect

Several types of calorimetric cell designs were used in attempts to measure excess enthalpy during the electrolysis of LiOD/D2O using palladium cathodes. Control experiments were run by using light water in place of D2O or by using platinum cathodes in place of palladium. Initial experiments using thin palladium cathodes of an unknown purity gave no significant differences between the Pd/D2O cells and the controls. For example, the ratio of heat out to Joule heat in was 1.00 ±0.04 for one study and 1.065 ±0.04 for another study in LiOD/D2O compared to 1.075 ±0.07 in LiOH/H2O. The use of a much thicker palladium rod (99.96%, d = 0.635 cm) from Johnson Matthey, however, resulted in calorimetric evidence for excess enthalpy in five out of six cells. The excess rate of heating averaged 0.39 W/cm over a 9-day period in one experiment. The total excess enthalpy observed was 110,000 J. This excess enthalpy is difficult to explain by chemical reactions. Similar experiments conducted in H2O did not produce significant amounts of excess enthalpy. Possible experimental errors in these calorimetric studies are being investigated. INTRODUCTION The electrochemically induced nuclear fusion of deuterium using a palladium electrode reported by Pons, Fleischmann, and Hawkins [1] has sparked a flurry of experimental measurements and considerable controversy [2-6]. The conditions under which this fusion may or may not occur will eventually be determined by many experiments at various laboratories. Enthalpy excesses that can exceed 10 W/cm of the palladium electrode have been claimed [1]. Similar experiments by Jones and coworkers [7] also report evidence for cold nuclear fusion; however, the fusion rates reported are far too small to be detected by calorimetry. The experiments described below are an attempt to detect any excess heat output by calorimetric studies during the electrolysis of deuterium oxide containing LiOD at palladium cathodes. Control measurements were run using light water with palladium cathodes or heavy water with platinum cathodes. Radiation levels were also monitored by various methods. EXPERIMENTAL The calorimetric cell design used in most experiments is shown in Figure 1. The electrolysis cell in this configuration can be visualized as a resistive heater with the temperature being measured in the secondary compartment (gap) surrounding the electrolysis cell. The electrolysis cell initially contained 18-20 g of 0.1 m LiOD/D2O (99.9%, Cambridge Isotope Laboratories) while the gap contained 68-70 g of distilled water. The alkaline solutions were prepared from lithium metal (ROC/RIC, 99.95%). This cell design minimized the decrease in the calorimetric cell constant with the decrease in the electrolyte solution volume which occurs during electrolysis. Both the electrolysis cell and plastic bottle (polyethylene) were stoppered and wrapped with parafilm to reduce evaporation and contamination. The evaporative losses from both the inner and outer glass vessels were 1% by weight per day. Make up water and heavy water were periodically added to the two compartments. After correcting for evaporation, the measured loss of D2O due to electrolysis was always within ±1% of the calculated value. The palladium rod cathode (Johnson Matthey, 99.96%, d = 0.635 cm, A = 2.64 cm) was spot-welded to a nickel lead. Both the anode and cathode leads were covered with heat shrinkable Teflon tubing to prevent exposure of the bare metal to the gases in the headspace. Two thermister thermometers (Cole-Parmer, Model 8502-16) calibrated within ±0.01°C were inserted into small glass tubes placed in the gap H2O and positioned 4.6 cm (T1, T4) and 1.9 cm (T2, T5) from the bottom of the cell. Two identical calorimetric cells containing two thermistors each as shown in Figure 1 were always run simultaneously in a constant temperature bath (Tbath = 27.50°C). Identical coils of Pt 20% Rh (5.35 g, d = 0.1 cm) served as the counter electrodes. Figure 1. Calorimetric Cell Design. Earlier experiments used a palladium wire cathode (d = 0.14 cm, A = 2.64 cm, Wesgo) of an unknown purity spot-welded to a Pt 20% Rh lead that was covered with heat-shrinkable Teflon tubing. Platinum wire cathodes (d = 0.12 cm, A = 2.64 cm) were used in several control experiments. Precision thermometers graduated in units of 0.1°C were used in these earlier studies. Several other calorimetric cell designs were also used that involved measuring the temperature directly in the electrolysis cell and using a correction factor to compensate for the decrease in the calorimetric cell constant with solution volume. The constant current source for electrolysis was a Princeton Applied Research (PAR) potentiostat/galvanostat (Model 373) set at 264 mA (100 mA/cm). Calorimetric cell constants were usually determined during the first day of electrolysis when no excess enthalpy is expected. Experiments using palladium cathodes in H2O or platinum cathodes in D2O gave nearly the same cell constants. In earlier experiments, calorimetric cell constants were determined by Joule heat calibrations with a 29 ohm resistor. RESULTS Calorimetric studies using the thin palladium and platinum wire cathodes in 0.1 m LiOD/D2O are presented in Figure 2. The equation