Plasma-Driven Synthesis of Self-Supported Nickel-Iron Nanostructures for Water Electrolysis

Nickel-based electrocatalysts are deemed as promising low-cost, earth-abundant materials in the development of the next-generation alkaline and anion exchange membrane water electrolyzers. Herein, a plasma-processing technique is presented for fabricating self-supported nanostructures from planar NiFe substrates and its performance for water splitting reactions. Irradiating the samples with helium plasma results in the formation of nano-tendrils, which are affixed to the metallic substrate. This unique design not only enhances charge and mass transport, but also increases the electrochemical surface area by 3 to 4 times, as compared to the unmodified/planar surfaces. For the benchmark 10 mAcm−2geo current density, the nanostructured electrodes demonstrate overpotentials of 330 and 354 mV for oxygen evolution reaction and hydrogen evolution reaction respectively in 1 M KOH. Moving forward, application of this technique can be extended for fabricating self-supported 3D substrates (e.g., foams, felts, perforated sheets), all of which find practical applications in energy conversion and storage devices.