Enhancement of hydrogen evolution activity by tailoring the electronic structure in ruthenium-heteroatom-doped cobalt iron phosphide nanoframes

Designing cost-effective and highly efficient electrocatalysts for hydrogen evolution reaction (HER) in alkaline media at high current densities is challenging. In this study, we adopted Ru heteroatom doping and an open nanoframe structure to obtain excellent HER catalytic performance. X-ray photoelectron spectroscopy (XPS) visualized the electron transfer due to Ru heteroatom doping in transition metal phosphides, to observe the modulated electronic structure of the Ru-doped CoFeP nanoframe (RCFP/NF). Density functional theory (DFT) calculations and XPS analysis confirmed a D-band center downshift of the RCFP/NF, demonstrating the regulation of the optimal adsorbates (OH*/H*) adsorption free energies. Consequently, RCFP/NF with 4.7 wt % of Ru exhibits a low overpotential of 112 mV, 191 mV, and 219 mV at current densities of 10 mA cm⁻², 100 mA cm⁻², and 500 mA cm⁻², respectively, and an excellent stability for 100 h at a high current density of 100 mA cm⁻². This outstanding HER performance at high current density was attributed to the hydrophilic and aerophobic properties of the RCFP/NF catalyst surface that facilitate the exposure of active sites and H₂ gas desorption.