Thermal effects on the measurement of photocurrent at anodic films on nickel electrodes

摘要

The influence of heat on the measurement of photocurrents at nickel electrodes in a 1 M NaOH solution was investigated by using photocurrent, photothermal and thermal current methods under the irradiation of laser beams with wavelengths of 488, 532 and 632 nm. respectively. It was found that the photocurrent appeared in the potential (vs. Hg / HgO electrode) region lower than- 0.1 V was caused by the p-type semiconductor property of Ni(OH)2 anodic film. In the Ni(OH){sub}2/NiOOH redox potential region the appearance of photocurrent was likely caused by the local temperature variation rather than the semiconductor properties of the anodic layer. Similar phenomena was observed for β-Ni(OH){sub}2 electrode. During the light irradiation an increase of temperature at the surface of the working electrode may disturb the measurement of photocurrent.