Challenges in hydrogen quantification using Kelvin probe technique at different levels of relative humidity

Kelvin probe-based contact potential measurements were conducted with in situ electrochemical hydrogen loading of a Pd membrane with a thickness of 100 μm. The theoretical basis of diffusion coefficient calculation based on measured response time of potential drop, arising from hydrogen arriving at the detection side of the Pd membrane, was discussed. In situ hydrogen loading was also utilized for insertion of different amounts of hydrogen into the Pd sample while monitoring the resulting contact potential difference changes. Measurement of contact potential difference at different final values of hydrogen concentration in the Pd membrane was performed at various atmospheric conditions, focusing in this work on increasing relative humidity (4 to 85% rH). Moreover, the effect of humidity changes on hydrogen effusion kinetics at room temperature and low oxygen content (<1%) was studied.