The global transition towards green hydrogen produced through sustainable methods has spurred the exploration of non-precious metal catalysts. While the catalytic performance of these non-precious catalysts—also referred to as non-platinum group metal (non-PGM) catalysts—is generally lower than that of PGMs, they offer significant economic and environmental advantages. Nanoparticulate nickel alloys, particularly Ni–Mo composites, have emerged as promising materials that help bridge the performance gap between PGMs and non-PGMs in alkaline hydrogen chemistry.1-3 Understanding the operational degradation of these materials is increasingly critical, as it provides critical information about practical performance in electrolyzer systems, along with insights about mechanisms of catalytic deactivation that can be used to design still better catalysts.
We have observed that Ni–Mo composites demonstrate superior stability in alkaline electrolytes containing chloride salts compared to platinum, as shown through accelerated stress tests using a thin-film rotating disk electrode setup. For example, incorporation of NaCl at 0.1 wt% in 1 M KOH electrolyte leads to a ~25% increase in the degradation rate—measured as the cathodic current density at a fixed iR-free overpotential—compared to pure 1M KOH control. By contrast, Ni–Mo composites exhibit markedly slower decrease in HER current in saline electrolytes.
Ongoing work focuses on evaluating these electrocatalyst using a half-cell gas diffusion electrode assembly4 to better assess electrolyzer cathode durability realistic operating conditions. These findings highlight the promise of Ni–Mo composites in terms of both material stability and durability, reinforcing their potential as competitive catalysts for the alkaline HER.
Reference:
Zeng & Li, J. Mater. Chem. A, 2015, 3, 14942–14962.
Raj, J. Mater. Sci., 1993, 28, 4375–4382.
Nairan et al., Adv. Funct. Mater., 2019, 29, 1903747.
Jiménez et al., J. Mater. Chem. A, 2023, 11, 20129–20138.
