Ginkgo Leaf-Derived Carbon Supports for the Immobilization of Iron/Iron Phosphide Nanospheres for Electrocatalytic Hydrogen Evolution

Abstract

Iron/iron phosphide nanospheres supported on ginkgo leaf-derived carbon (Fe&FeP@gl-C) are prepared using a post-phosphidation approach, with varying amounts of iron (Fe). The activity of the catalysts in the hydrogen evolution reaction (HER) outperforms iron/iron carbide nanospheres supported on ginkgo leaf-derived carbon (Fe&Fe_x C@gl-C), due to enhanced work function, electron transfer, and Volmer processes. The d-band centers of Fe&FeP@gl-C-15 move away from the Fermi level, lowering the H₂ desorption energy and accelerating the Heyrovsky reaction. Density functional theory (DFT) calculations reveal that the hydrogen-binding free energy |ΔG_H* | value is close to zero for the Fe&FeP@gl-C-15 catalyst, showing a good balance between Volmer and Heyrovsky processes. The Fe&FeP@gl-C-15 catalyst shows excellent hydrogen evolution performance in 0.5 m H₂ SO₄ , driving a current density of 10 mA cm^-2 at an overpotential of 92 mV. Notably, the Fe&FeP@gl-C-15 catalyst outperforms a 20 wt% Pt/C catalyst, with a smaller overpotential required to drive a higher current density above 375 mA cm^-2 .

Keywords: ginkgo leaf-derived carbon; hydrogen evolution reaction; iron catalysts; iron/iron phosphides nanospheres; post-phosphidation.