Nanoarchitecturing hydrogen electrode with intimately coupled ion-conducting and catalytic phases for enhanced intermediate-temperature steam electrolysis.

Intermediate-temperature solid oxide electrolysis cells (IT-SOECs) have recently attracted great interest in steam electrolysis. However, the performance of IT-SOECs is substantially influenced by the polarization loss encountered at the traditional hydrogen electrode interface. Herein, we reported an innovative approach to address this challenge by modifying the interface of hydrogen electrode and electrolyte. NiO-BaZr 0.1 Ce 0.7 Y 0.2 O 3-δ (NiO-BZCY) nanocomposite with an even distribution of NiO and BZCY was synthesized by a one-step combustion method and utilized to fabricate a hydrogen electrode functional layer (HFL). In comparison with the conventional hydrogen electrode fabricated by the ball-milling method, the developed double-layer hydrogen electrode structure exhibits a gradient porosity with macropores at the electrode substrate and micropores at HFL. The optimized electrode microstructure provides both adequate gas diffusion pathway and enlarged three-phase-boundary for effective electrochemical reaction. Consequently, the polarization loss is significantly reduced, leading to a discernible enhancement in the electrolysis performance of the IT-SOECs. [Display omitted] • The cathode microstructure is modified with hydrogen electrode functional layer made by one-step combustion of NiO-BZCY. • The graded-porous structure improves gas diffusion and triple-phase boundary length in hydrogen electrode. • High current density of 0.74 A cm−2 is achieved at 1.3 V and 700 °C. • The polarization loss is effectively reduced at the cathode/electrolyte interface. [ABSTRACT FROM AUTHOR]