Cross-Interface Diffusion-Driven Exsolution of Praseodymium Oxide Nanoparticles for Enabling Electrolysis at Industrially Relevant Temperatures in Protonic Ceramic Cells

Abstract

Protonic ceramic electrolysis cells (PCECs) can unlock direct electrification of catalytic processes towards intensification and operation at intermediate temperatures (400-650 oC). A primary challenge however is the development of the steam splitting electrocatalyst (positrode) that will enable the hydrogen production. Here we have developed highly efficient and self-configured positrodes, consisting of a triple-conducting (H+, O2-, e-) Pr0.95Ca0.05Ni0.5Co0.5O3-δ perovskite matrix and exsolved praseodymium oxide nanoparticles. We show for the first time that the nanoparticle nucleation is triggered by the cross electrode-electrolyte interface ion diffusion by simply sintering in ambient air. To boost nanoparticles’ population, we also employ strategies such as acid treatment to control surface defects. This approach doubles the electrochemical performance compared to the pristine cell, accompanied with >95% faradaic efficiency and exceptional durability for >500 h. Our work exemplifies how the previously unexplored interfacial ion interactions can be engineered to enable highly efficient renewable hydrogen production at industrially relevant temperatures.