Phase reconstruction of Ni2P/NiSe2 heterostructure with co doping as bifunctional electrocatalyst for boosting overall water splitting

Co doped Ni 2 P/NiSe 2 nanowires is rationally prepared for water splitting in alkaline media. • Reconstruction process and the active species changes are discussed by in situ Raman. • Partial reconstructed product shows excellent activity and stability for OER. • DFT reveal that Co site is active site for OER and Ni-Co dual sites are favorable for HER. • Co doped Ni 2 P/NiSe 2 exhibits extraordinary bifunctional electrocatalytic performance with robust stability. Designing efficient and low-cost bifunctional electrocatalysts is critical for advancing the practical application of water electrolysis for hydrogen production. Herein, we propose a dual modulation strategy to construct Co doped Ni 2 P/NiSe 2 Heterogeneous electrocatalysts (Co-Ni 2 P/NiSe 2 ) with staggered structure for boosting alkaline water splitting. Operando Raman spectroscopy was employed to monitor the evolution of active species, revealing that Co doping facilitates the phase transition of Co-Ni 2 P/NiSe 2 from β-NiOOH to γ-NiOOH under operando electrochemical conditions. Density functional theory (DFT) calculations further clarify the origin of active site in Co-Ni 2 P/NiSe 2 , demonstrating that the Co site promotes the oxygen evolution reaction (OER), whereas the Co-Ni dual sites exhibit superior activity toward the hydrogen evolution reaction (HER). The reconstructed Co-Ni 2 P/NiSe 2 exhibits a low overpotentials of 218 and 108 mV at 10 mA cm −2 for OER and HER, respectively. Furthermore, the two-electrode electrolyzer needs a low cell voltage of 1.47 V at 10 mA cm −2 and maintains exceptional durability for over 500 h at 100 mA cm −2 . This work presents a novel mechanistic insight into the design of promising bifunctional electrocatalyst. Download: Download high-res image (113KB) Download: Download full-size image