The development of efficient, durable, and cost-effective electrocatalysts for the oxygen evolution reaction (OER) remains a critical challenge in sustainable energy technologies. In this work, we present a high-performance Fe-doped Ni@NC hierarchical hollow microsphere catalyst synthesized through the direct pyrolysis of a metal-organic framework (MOF) precursor. The synthesis began with the solvothermal formation of a microspherical Ni-based MOF doped with 5 mol% iron, using nickel chloride hexahydrate, trimesic acid, and iron(III) chloride as precursors, with PVP serving as a stabilizing agent. This structure was then subjected to thermal treatment under an inert argon atmosphere at 450 °C for 2 hours, resulting in the conversion into Fe-Ni@NC microspheres composed of metallic Ni nanoparticles embedded within a nitrogen-doped carbon matrix.
Structural characterization confirmed the successful retention of the spherical morphology after pyrolysis, as observed in SEM images showing smooth yet roughened surfaces compared to the original MOF. TEM and HRTEM analyses revealed well-dispersed Ni nanoparticles (~10–20 nm) encapsulated by thin carbon layers, with clear lattice fringes of 0.202 nm corresponding to the (111) plane of face-centered cubic Ni. Elemental mapping demonstrated uniform distribution of Fe, Ni, C, and N, confirming effective doping and integration of heteroatoms into the carbon network. XPS analysis further verified the presence of metallic Ni (852.Acetyl Lysine Antibody Formula 7 eV), Ni²⁺ (855.KCNAB1 Antibody Purity 2 eV), and Fe (706.1 eV), along with significant contributions from pyridinic (398.5 eV), pyrrolic (399.3 eV), and graphitic (400.6 eV) nitrogen species, indicating enhanced charge transfer capability.
Electrochemical evaluation in 1.0 M KOH revealed that the Fe(5%)-Ni@NC catalyst exhibited outstanding OER activity. Linear sweep voltammetry (LSV) showed an overpotential of just 257 mV at 10 mA cm⁻², surpassing undoped Ni@NC and matching or exceeding the performance of commercial RuO₂ at higher current densities. The Tafel slope of 54.6 mV dec⁻¹ indicated rapid reaction kinetics, while EIS data displayed a smaller semicircle radius than Ni@NC, reflecting lower charge transfer resistance. The double-layer capacitance (Cdl) of Fe(5%)-Ni@NC reached 5.58 mF cm⁻², nearly twice that of Ni@NC (2.68 mF cm⁻²), implying a larger electrochemically active surface area due to hierarchical porosity and increased site exposure.
Long-term stability was rigorously tested: after 2000 CV cycles between 1.3 and 1.8 V (vs RHE), the catalyst retained its activity with negligible decay. Chronoamperometry at 1.PMID:34716547 50 V (vs RHE) maintained stable current density for over 20 hours without significant loss. Post-cycling XPS analysis revealed an increase in Ni²⁺ and NiOOH-related peaks (855.2 eV), suggesting the formation of catalytically active phases during operation. Simultaneously, the Fe 2p signal shifted toward higher binding energies, indicating oxidation to Fe³⁺ or Fe⁴⁺ states, which may promote electron redistribution and enhance OER efficiency. These findings confirm that Fe doping not only improves intrinsic activity but also stabilizes the catalyst surface under harsh oxidative conditions.
This study demonstrates that MOF-derived Fe-Ni@NC hierarchical microspheres represent a promising class of non-precious metal electrocatalysts for alkaline water electrolysis. The synergy between Fe incorporation, nitrogen doping, and hierarchical architecture enables exceptional activity, fast kinetics, and robust durability—key attributes for practical hydrogen production applications. The facile and scalable synthesis method further supports potential industrial adoption.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
