A piston reactor technique for rapid, binder-free nanoparticle deposition: Nickel-modified copper foam electrodes for enhanced oxygen evolution reaction

The development of cost-effective and durable electrodes for the oxygen evolution reaction (OER) is essential for advancing sustainable hydrogen production. In this work, we introduce a piston reactor as a novel platform for the synthesis and direct deposition of carbon and nickel nanoparticles onto copper (Cu) foam substrate. The piston-assisted method enables rapid, high-temperature nanoparticle formation and uniform coating without binders. Structural and morphological analyses (SEM-EDX, XRD, and XPS) confirmed the formation and successful deposition of nanostructured carbon and nickel particles on the 3D copper support with good adhesion. Electrochemical measurements demonstrated that Ni@Cu foam significantly enhanced OER activity compared to bare Cu and carbon-coated Cu, achieving an overpotential of 360 mV at 10 mA cm⁻² with a Tafel slope of 67.7 mV dec⁻¹. Parametric studies revealed that shorter deposition times and lower piston speeds favored catalytic performance, while prolonged deposition and the use of glycine as an additive led to decreased activity due to thicker or altered coatings. These findings establish an initial methodology/breakthrough communication to use the piston reactors for fabricating binder-free, nanostructured electrodes, with potential applications in water splitting and other electrochemical energy systems.