Enhancement of deuterium enrichment efficiency in PEM water electrolysis via isotope exchange equilibrium shift

矢野 雅大   ; 久保 真治  ; 保田 諭   

Yano, Masahiro; Kubo, Shinji; Yasuda, Satoshi

This study presents an in-situ, liquid phase catalytic exchange (LPCE)-based process-intensification approach for hydrogen-isotope separation in proton-exchange membrane water electrolysis (PEM-WE). Supplying water directly to the cathode enables deliberate tuning of the local isotopic composition at the catalyst surface, which in turn enhances both the separation factor and the deuterium enrichment efficiency. A chemical-equilibrium model reproduces these trends by attributing the gain to a thermodynamic shift of the LPCE toward the liquid phase at the cathode. The effectiveness of the method was validated across a wide range of initial deuterium concentrations in the anode feedwater and under high current densities, indicating its versatility. This approach offers a promising and practical strategy for efficient hydrogen isotope separation using PEM-WE.