Efficient and stable 40 W-class low-temperature NH3 electrolyzers for intermittent H2 production

Abstract

Low-temperature NH3 electrolysis has emerged as a promising method for carbon-free H2 production, utilizing NH3 as a cost-effective H2 carrier. While most research has focused on NH3 oxidation catalysts, the efficiency, stability, and scalability of NH3 dehydrogenation devices remain underexplored. Here, low-temperature NH3 electrolyzers achieving peak current densities over 1.5 A cm−2 are demonstrated with high efficiency and stability. Electrochemical and chemical regeneration protocols were developed to enhance coulombic efficiency and durability. Using these protocols, ∼90% coulombic efficiency was sustained at 0.67 A cm−2 for 50 min without degradation. Surface poisoning behaviors under different protocols were examined by combining in-situ ATR-SEIRAS (attenuated total reflectance surface-enhanced infrared absorption spectroscopy) with electrochemical analysis. Finally, a 40 W NH3 electrolyzer stack with a 25 cm2, 3-cell configuration showed stable operation at 0.72 A cm−2 for 200 min, with a degradation rate of 75.7 μA cm−2 min−1 under voltage swing operation. This work establishes a systematic approach to low-temperature NH3 electrolysis, enabling stable and efficient intermittent H2 production.