Surface Charge and d-Band Structure Modulation of CoP by Fe Doping for Efficient Hydrogen Evolution Reaction at All pH Values

Excessive adsorption and tough desorption of H species limit the hydrogen evolution reaction (HER) activity and kinetics of phosphides. Herein, N-doped carbon-anchored Fe-doped CoP hollow nanododecahedrons (Fe–CoP/NC) were synthesized via a coordination, ligand substitution, and phosphorization multiple-step strategy. The strong coordination of [Fe(CN) 6 ] 3– with Co 2+ triggers the transition from ZIF-67 to CoFe-prussian blue analogues (CoFe-PBAs), and phosphorization endows the electrocatalyst with a hollow morphology, facilitating subtle interactions between metal and P atoms. First, tailored hollow nanododecahedrons accelerate mass transport and charge transfer. Meanwhile, Fe doping creates lattice distortion and P vacancies (P v ) to increase the amount of species capture sites. Most notably, the incorporation of Fe optimizes the surface charge distribution on P sites, downshifts the Co d-band center, and achieves dynamic conversion of H-interaction sites for moderate adsorption and fast desorption, thereby reducing the energy barrier of the rate-determining step (RDS). As a result, Fe–CoP/NC exhibits far less acidic HER overpotential (61 [email protected] A cm –2 ) and Tafel slope (48.24 mV dec –1 ) than CoP/NC and is applicable in alkaline and neutral media. The assembled Fe–CoP/NC∥RuO 2 electrode can drive 1.0 A cm –2 under industrial conditions in a proton exchange membrane (PEM) electrolyzer with only 1.91 V. This work provides new insight for designing efficient and economic HER electrocatalysts with all pH adaptation.