Hierarchical C@CoFeSi-P core-shell nanostructures with vertically aligned nanosheets for efficient oxygen evolution reaction via synergistic Fe doping and phosphate modification

The development of efficient, non-precious electrocatalysts for the oxygen evolution reaction (OER) is critical for sustainable energy conversion technologies. Here, a core-shell structured catalyst C@CoFeSi-P, with vertically aligned cobalt iron silicate nanosheets grown in-situ on hollow mesoporous carbon spheres (HMCS), is synthesized via the hard-template-assisted hydrothermal method followed by low-temperature phosphating. To solve the sluggish kinetics of OER, this design integrates hierarchical porosity, conductive carbon matrices, and optimized electronic structures. The characterization results reveal that Fe doping induces lattice expansion in Co 2 SiO 4 , and phosphate modification generates an amorphous surface rich in unsaturated coordination sites, which collectively enhances the adsorption of oxygen intermediates (*OH, *O, and *OOH). The density functional theory (DFT) calculations demonstrate that the synergistic effects of Fe incorporation and PO 4 3- groups lower the energy barrier (ΔG = 0.29 eV) for the potential-determining step (*O → *OOH), accelerating reaction kinetics. This C@CoFeSi-P catalyst reaches superior OER performance, with overpotentials of 277 mV at 10 mA cm −2 and 404 mV at 100 mA cm −2 . Except that, it also exhibits remarkable stability over 40 h, surpassing most reported transition metal silicate-based catalysts. Furthermore, the Pt/C‖C@CoFeSi-P system displays superior overall water-splitting efficiency compared to conventional Pt/C‖RuO 2 , highlighting its practical potential. This work provides a guidance for multi-scale modulation of electrocatalysts through atomic doping and surface engineering, offering a cost-effective alternative to noble-metal-based systems for sustainable energy applications.