Novel synthesis of amorphous/defect-rich NiFe(O)OH nanosheets for alkaline electrolyzers at high current density

Driven by the imperative to mitigate fossil fuel-induced environmental crises, hydrogen emerges as a pivotal clean energy vector. While alkaline water electrolysis (AWE) enables sustainable hydrogen generation, its efficiency is bottlenecked by noble metal catalysts' intrinsic constraints in cost and durability. Traditional synthesis methods (e.g., hydrothermal, electrodeposition) face inherent challenges: multi-step complexity, poor batch reproducibility, and inadequate defect density control. Hence, we pioneer a scalable two-step strategy integrating magnetron co-sputtering with selective alkaline corrosion, directly fabricating amorphous defect-rich NiFe(O)OH nanosheets on nickel foam. The obtained structure shows an interlaced nanosheet structure with super hydrophilicity, enhancing the exposure of active sites and accelerating charge transfer. The nanostructured NiFeO x H y catalyst demonstrates exceptional OER performance, with overpotentials of 288 mV at 100 mA cm⁻². Notably, when integrated into an anion exchange membrane (AEM) water electrolyzer as the OER catalyst, the material demonstrates industrial-grade durability by maintaining stable operation for at least 107 h under extreme industrial operation parameters: sustained ultrahigh current density of 2 A cm⁻² at 80 °C in 1 M KOH electrolyte, bridging the gap between laboratory innovation and industrial hydrogen production. A two-step method via magnetron co-sputtering and selective alkaline corrosion fabricates amorphous and defect-rich NiFe(O)OH nanosheets on nickel foam. The resulting electrocatalyst achieves notable performance metrics, including an oxygen evolution reaction (OER) overpotential of 288 mV at 100 mA cm⁻² and sustained operation for 107 h at ultrahigh current densities up to 2 A cm⁻² in 1 M KOH electrolyte (80 °C). These breakthroughs demonstrate the method's promising potential for industrial-scale hydrogen production applications. • Scalable two-step fabrication of amorphous, defect-rich NiFe(O)OH nanosheets via magnetron co-sputtering. • NiFeO x H y achieves 288 mV overpotential at 100 mA cm⁻² for OER. • NiFeO x H y in AEM electrolyzer runs 107 h at 2 A cm⁻² (1 M KOH, 80 °C).