NiMo sputter-deposition on tape-casted NiFe foam for anion exchange membrane water electrolysis

Abstract

Anion exchange membrane water electrolysis (AEMWE) offers a sustainable route for green hydrogen production. However, its large-scale deployment is constrained by the limited activity and stability of non-precious metal electrocatalysts, as well as challenges in designing efficient porous transport layers (PTLs). In this study, NiMo thin films were sputter-deposited onto tape-cast NiFe foam to construct bifunctional catalytic PTLs for AEM cells operated under both cathode-wet and cathodedry conditions. The cell operating under cathode-wet conditions exhibited a higher current density at 1.8 V (85.5 mA/cm 2 at 70℃) compared to that under cathode-dry operation (46.0 mA/cm 2 at 70℃). When NiMo@NiFe foam was employed as the anode and coupled with a Ru/carbon paper (Ru/CP) cathode, the AEM cell achieved 820 mA/cm 2 and 784.8 mA/cm 2 at 1.8V and 70 ℃ under cathode-dry and cathode-wet operation, respectively, outperforming the symmetric NiMo@NiFe foam system. In addition, temperature-dependent polarization analyses were conducted to investigate the temperature sensitivity of both systems. The influence of temperature on HER performance under cathode-dry operation was further discussed based on the catalytic mechanisms associated with different cathode PTLs. To evaluate the stability under intermittent power input, an accelerated stress test (AST) was performed. The cathode-wet symmetric cell exhibited a current density decrease from 41.8 to 27.5 mA/cm 2 at 1.8 V after 5000 cycles at 25 ℃. This work integrates sputtered NiMo with tape-cast NiFe foam as a scalable catalytic PTL design, providing insights into the effects of temperature on AEMWE operation, and the potential and remaining challenges of non-precious PTLs for practical AEMWE systems.