Plasma-Driven Synthesis of 3D Self-Supported Ni-Fe Nanostructures for Green Hydrogen Production

Abstract

Hydrogen is considered as a future energy carrier due to its desirable characteristics such as high energy density, wide range of applications, and near-zero greenhouse gas emissions. Amongst the various hydrogen production methods, electrochemical water splitting is a promising alternative for producing large-scale green hydrogen. Recently, Anion Exchange Membrane Water Electrolysis (AEMWE) has garnered special attention due to its advantages such as use of low-cost materials and higher performance over conventional techniques such as Alkaline Water Electrolysis (AWE) or Proton Exchange Membrane Water Electrolysis (PEMWE).In the development of anodic electrodes for AEMWE, nickel-based materials have been extensively studied as promising low-cost substitutes to expensive noble metal catalysts such as IrO2 and RuO2. To improve the catalytic performance, interfacial engineering, intercalation, nanostructuring techniques are commonly used1. The nanostructured catalysts are typically synthesized in powder form, which then requires a binder to coat them on a substrate. The extra interfaces between the catalyst, substrate and the electrolyte can cause charge and mass transfer limitations as well as restrict the availability of active sites2. Under gas evolution conditions, it can also lead to mechanical shedding and delamination of catalysts. This limits the applicability of emerging electrocatalysts on a commercial scale, thus making it essential to explore novel fabrication routes for synthesizing self-supported nanostructures.Helium plasma irradiation is a potential alternative wherein the nanostructures are created on the substrate itself, and thus can potentially alleviate some of the shortcomings of conventional methods. The plasma irradiation technique has been extensively studied in relation to the surface erosion and embrittlement of fusion reactors3,4. However, its application has been limited mostly to planar surfaces and only a few studies have employed this technique in solar-to-hydrogen production5,6. Herein, we report plasma-driven synthesis of nanostructured 3D electrodes and their integration in a membrane electrode assembly (MEA).The MEA with self-supported nanostructures delivers ≈25% higher performance than its bare counterpart at room temperature. Additionally, iron incorporation further increases the performance, surpassing commercially available NiFe electrocatalysts. Going forward, the durability and performance of the self-supported electrodes at higher temperatures will be explored and the applicability of this technique to other renewable energy systems is expected to be correlated.