Synergistic core–shell boosts P-CoNiMoO@Co2P-Ni2P bifunctional catalyst for efficient and robust overall water splitting

Optimizing hydrogen adsorption and enhancing water absorption are essential for the design of effective hydrogen evolution reaction (HER) electrocatalysts. Herein, a well-defined core–shell-structured P-CoNiMoO@Co 2 P-Ni 2 P catalyst was synthesized on nickel foam via high-temperature phosphidation of heterostructured precursor CoMoO 4 ·xH 2 O/NiMoO 4 ·xH 2 O with hydrogen (H 2 ) assistance. This catalyst exhibits good HER performance, requiring only 24 mV of overpotential to achieve a current density of 10 mA cm −2 , and long-term stability, maintaining a current density of 100 mA cm −2 for over 100 h. Density functional theory calculations indicate that the molybdenum site is highly favorable for water adsorption in phosphorus-doped cobalt nickel molybdate (P-CoNiMoO), while the trigonal Ni 3 site is optimal for hydrogen adsorption. These findings indicate that the cooperative interactions and functional division between the core and shell substantially enhance HER performance. In addition, P-CoNiMoO@Co 2 P-Ni 2 P demonstrates high oxygen evolution reaction performance, achieving a current density of 10 mA cm −2 at an overpotential of 243 mV. When functioning as a bifunctional electrocatalyst, it requires only 1.49 V to drive overall water splitting at a current density of 10 mA cm −2 , with a durability of over 200 h at current densities of 100 and 300 mA cm −2 . This study provides significant insights into the development of HER catalysts with potential applications in other fields.