Ru-modified NiFe2O4/NiO heterojunction for high-performance alkaline hydrogen evolution

Precious metals like Pt, Ir, and Ru are highly efficient catalysts for the hydrogen evolution reaction (HER) in acidic environments; however, their efficiency significantly decreases in alkaline environments due to the slow kinetics of water dissociation. Doping and interface engineering have emerged as effective ways to improve water-splitting performance. This study introduces a novel Ru-doped flower-like heterostructure catalyst (Ru-NiFe₂O₄/NiO) vertically grown on nickel foam (NF) via a simple hydrothermal method followed by annealing. The improved catalyst derives advantages from electronic structure modulation, a hierarchical nanosheet architecture rich in active sites, and tailored hydrogen adsorption characteristics. As a result, Ru-NiFe₂O₄/NiO demonstrates remarkable HER activity, exhibiting overpotentials of merely 17 mV and 78 mV at current densities of 10 and 100 mA cm⁻², respectively, alongside a low Tafel slope of 37.98 mV dec⁻¹, surpassing that of commercial 20 % Pt/C. An assembled alkaline electrolyzer utilizing Ru-NiFe₂O₄/NiO‖NiFe achieves a cell voltage of 1.513 V and maintains stable operation for over 30 h at a current density of 10 mA cm⁻², surpassing the RuO₂‖Pt/C benchmark (1.62 V). This study presents an effective approach for the development of efficient HER catalysts through heterostructure engineering and noble metal doping.