Rapid Liquid-Phase Plasma Synthesis of Surfactant-Free Colloidal Ni-Fe Nanoparticles for Highly Efficient Oxygen Evolution Reaction

초록

The oxygen evolution reaction (OER) is a fundamental bottleneck in overall water electrolysis due to its sluggish kinetics, necessitating the development of highly active and earth-abundant electrocatalysts. While nickel-iron (Ni-Fe)–based materials are highly promising, conventional wet-chemical syntheses often require hazardous precursors and surfactants that block catalytic active sites. In this study, we demonstrate a facile, rapid, and single-step liquid-phase plasma (LPP) discharge process to synthesize highly pure and surfactant-free colloidal Ni-Fe–based nanoparticles directly in ethyl alcohol. The LPP process utilizes localized Joule heating to overcome the dielectric barrier, enabling ultrafast nucleation of bare nanoparticles. When electrodeposited onto a carbon cloth substrate (Col-NiFe-C.C.), the resulting electrode exhibits exceptional intrinsic OER electrocatalytic performance in 1.0 M KOH. It achieves a benchmark current density of 100 mA cm−2 at a low overpotential of 400 mV and a favorable Tafel slope of 42.2 mV dec−1, significantly outperforming commercial IrO2 catalysts. Furthermore, the Col-NiFe-C.C. catalyst demonstrates robust long-term durability, maintaining stable continuous electrolysis at 10 mA cm−2 for 100 h with negligible degradation. This work presents a scalable and environmentally benign process for the design and fabrication of advanced transition metal nanocatalysts for alkaline water electrolysis.

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