Controlled synthesis of NiFe alloy nanoparticles confined in carbon matrices: study on the effect of morphology on...

The development of efficient and noble-metal-free electrocatalysts for the Oxygen Evolution Reaction (OER) is critical for advancing renewable energy technologies. In particular, the performance is highly dependent on the structure and morphology of the catalysts. Herein, we present a facile and template-free strategy to precisely control the morphology of bimetallic NiFe nanoparticles supported on various carbon matrices. These NiFe nanoparticles (NiFe/C) promote in situ carbon deposition to achieve nanocomposites with unique morphologies, ranging from nanoparticles to complex nanotubes and nanosheets. Among the prepared catalysts, the NiFe/AC catalyst self-assembled into a tubular structure, showing superior performance with a low overpotential of 253 mV at 10 mA cm^-2 and long-term stability for a 50-h OER process. A combination of experimental characterizations and density functional theory calculations reveals that the improved performance is attributed to the Ni/Fe oxyhydroxide and the metal-support interactions. The interactions modulate electronic structures of Ni/Fe and shift the d-band centre of the cataltsts, lowering the Gibbs free energy and thereby enhancing OER performance. The morphology-performance relationship of NiFe alloy with carbon materials is established, which highlights how tailored carbon matrices optimize both the local environment and intrinsic activity of active sites.