Heat Measurement in Hydrogen Absorption into Metal Composite Powder and Thin Films

Recent studies have reported excess heat generation during hydrogen absorption–desorption cycles in Cu–Ni composite metals. It has also been suggested that laser irradiation of the sample can enhance the reactions of hydrogen within metals. Considering these findings, we investigated the thermal behavior of hydrogen-loaded Cu–Ni alloys supported on zirconia (CNZ). In absorption experiments with a heater input of 50 W, maximum excess heat of 16 W was observed. Furthermore, when laser irradiation at a wavelength of 793 nm with an output power of 1–6325 mW was applied to the CNZ sample, the excess heat calculated from the sample temperature was positive, whereas that derived from the gas temperature was negative. In addition, hydrogen desorption experiments using Pd–Ni multilayers deposited on a zirconia substrate were carried out. The results showed that excess heat occasionally became negative depending on the heater power, indicating poor reproducibility.