Nano-Pd loaded composite membrane for reduced hydrogen crossover in proton exchange membrane water electrolysis via recasting method

The operation safety of proton exchange membrane water electrolysis (PEMWE) is significantly affected by hydrogen crossover. To address this issue, this study proposes a nano-Pd particle loaded composite membrane (Nafion-Pd) using the recasting method. Nafion-Pd and commercial membrane (Nafion-115) are comparatively studied in terms of the structure characteristics, proton conductivity, stability, electrolysis performance and hydrogen crossover. The results show that the Pd particles are relatively evenly distributed in Nafion-Pd, and the doped Pd particles have minor effect on the crystallinity and wettability of the membrane. Compared with Nafion-115, the composite membrane shows a slightly decreased ion exchange capacity but a significantly increased water absorption and hydration degree, which results in a 24.8 % increase in the proton conductivity. Although the mechanical stability of Nafion-Pd decreases to a certain extent, both the oxidative stability and thermal stability are improved. The electrolysis performance of PEMWE using Nafion-Pd is slightly improved, and the hydrogen crossover decreases significantly. Hydrogen concentration in oxygen is 0.66 % at 0.1 A/cm2, which is 60.2 % and 19.5 % lower compared with the Nafion 115 and Pt-doped composite membrane, respectively. The electrolytic voltage and hydrogen concentration in oxygen are relatively stable in long-time operation, ensuring an economic and safe operation of PEMWE.