Tailoring Fe-doped Co3O4 nanoparticles via ultrasonic cell disruption: mechanistic insights and high-performance alkaline HER electrocatalysts†

In this study, Fe-doped Co₃O₄ nanoparticles were synthesized using a hydrothermal method followed by ultrasonic cell disruption to enhance the alkaline hydrogen evolution reaction (HER) performance. Through a dual-modification strategy combining elemental doping and morphology engineering, structural characterization confirmed that Fe doping induces lattice distortions and optimizes the electronic structure, while ultrasonic cell disruption effectively reduces particle size to ∼50 nm and increases active site density. The 10Fe-Co₃O₄ ultrasonicated nanoparticle (UNP) catalyst showed remarkable HER performance, with overpotentials of 210.7 mV and 264.0 mV at 10 and 100 mA cm⁻², respectively, and a Tafel slope of 75.2 mV dec⁻¹ in 1 M KOH. DFT calculations indicate that Fe doping improves water adsorption, lowers energy barriers in the Volmer and Heyrovsky steps, and shifts the d-band center, thereby accelerating HER kinetics. The 10Fe-Co₃O₄ UNP catalyst also demonstrated excellent durability, maintaining stable performance over 24 hours at high current densities. This work highlights the potential of Fe-doped Co₃O₄ as a cost-effective, high-efficiency, non-noble metal-based catalyst for the HER, providing valuable insights into catalyst design and advancing sustainable hydrogen production technologies.