In-situ grown FeP nanoparticles on Fe,P Co-doped porous carbon spheres: synergistic heterostructures for low-overpotential oxygen evolution reaction

The surge in the need for eco-friendly hydrogen energy via water splitting has spurred intensive research into non-precious metal electrocatalysts for the oxygen evolution reaction (OER). Herein, a reliable hydrothermal, carbonization and phosphorization strategy was adopted to synthesize the FeP/CS electrocatalyst, where iron phosphide nanoparticles were in-situ grown on iron and phosphorus co-doped porous carbon spheres. This unique heterostructure features Fe,P co-doping within the carbon matrix for enhanced conductivity and FeP nanoparticles anchored on the carbon surface for boosted intrinsic activity. The optimized FeP/CS exhibits superior OER catalytic activity, achieving 10 mA cm −2 at an overpotential of 273.9 mV and a Tafel slope of 68.6 mV dec −1 . It also demonstrates promising long-lasting reliability, showing merely 9.2% current degradation after 50 h of chronoamperometry. Density functional theory calculations indicate that the FeP/CS heterostructure increases the density of states near the Fermi level, enhances charge transfer, and remarkably reduces the Gibbs free energy barrier of the rate-determining step (O* → OOH*) from 2.96 eV (Fe/CS) to 2.50 eV (FeP/CS). This work demonstrates that the synergistic combination of internal co-doping and in-situ interfacial engineering between metal phosphide and carbon matrix effectively boosts both the activity and stability of transition-metal phosphide-based electrocatalysts, and it can serve as a practical guideline for the rational engineering of superior OER electrocatalysts.