Extraction of hydrogen into vacuum by electrochemical hydrogen pump for hydrogen isotope recovery

For hydrogen isotope recovery, an electrochemical hydrogen pump using CaZr_0.9In_0.1O_3?α under vacuum in the cathode compartment has been proposed. Two types of electrodes—pasted and electroless plated electrodes—were used to evaluate the mass transfer process. When the hydrogen pump was operated using direct current, the voltage between electrodes under vacuum was less than that under atmospheric pressure, regardless of electrode type. This result indicates that the hydrogen pump performance is improved under vacuum. In the case of the pasted electrode, however, the voltage decrease was larger than that in the case of the plated electrode. Electrochemical impedance spectroscopy revealed that the diffusivity in the pasted electrode was smaller under atmospheric pressure than under vacuum. From comparing the microstructures of the two electrode types, the pasted electrode has larger pores and would be more suitable for the hydrogen pump under vacuum.