Efficient high-temperature electrochemical hydrogen pump via modulating phosphoric acid distribution in binderless catalyst layers

Controlling the distribution of phosphoric acid (PA) within the catalyst layers of electrochemical hydrogen pumps (EHP) incorporating PA-doped high-temperature polymer electrolyte membranes (HT-PEM) is essential for enhancing their performance. In this study, simulation results indicate that PA content decreases from the membrane toward the gas diffusion layer. To mitigate the gradient, the contact angle of the catalyst layers is reduced by decreasing the binder content. Furthermore, incorporating PA into the catalyst layers with an optimum content of 3 mg cm−2 also improves the electrochemical surface area of the Pt catalyst. When fed with methanol reforming gas, the HT-PEM EHP with optimized catalyst layers achieves 99.9% H₂ selectivity at 0.115 V and 0.5 A cm−2 at 160 °C and operates stably for over 100 h. This study on PA modulation within the catalyst layers of HT-PEM EHPs provides a valuable approach for improving their performance at elevated temperatures.