Continuous lattice oxygen participation of NiFe stack anode for sustainable water splitting

Abstract

Non-noble anode catalysts exhibit insufficient activity and stability for anion exchange membrane water electrolysis (AEMWE). Accordingly, we propose an electrolyte additive strategy involving NiFe-layered double hydroxide. In situ Raman spectroscopy and 18O isotope labeling experiments reveal that Fe ions in the electrolyte change the oxygen evolution reaction mechanism from adsorbate evolution to the lattice oxygen participation mechanism (LOM). These Fe ions continuously refill Fe vacancies owing to facile metal dissolution via the LOM. In a unit cell, we achieve an excellent cell voltage of 1.73 V and energy conversion efficiency (ECE) of 69.4 % at 3.0 A cm−2, meeting the target set by the U.S. Department of Energy (1.80 V and 69.0 % ECE). Our optimized membrane electrode assembly enhances the cell activity (1.567 V at 1.0 A cm−2; ECE = 76.5 %) and stability (0.125 mVcell h−1 at 0.5 A cm−2 for 500 h) with a 100 cm2 AEMWE stack. © 2024