Phase interface engineering of metal selenides heterostructure for enhanced lithium-ion storage and electrocatalysis

Biphasic or multiphase heterostructures hold attractive prospects in engineering advanced electrode materials for energy-related applications owing to the appealing synergistic effect; however, they still suffer from unsatisfied electrochemical activity and reaction kinetics. Herein, guided by density functional theory calculation, a well-engineered selenides heterostructure with high-density Ni₃Se₄-NiSe₂ biphasic interfaces that fastened in N, O-codoped carbon matrix, was developed for high-performance lithium storage and electrocatalysis. By controlled selenylation of metal-organic framework (MOF), a series of NiSe_x@C hybrids (Ni₃Se₄@C, Ni₃Se₄/NiSe₂@C-1, Ni₃Se₄/NiSe₂@C-2, and NiSe₂@C) with tunable biphasic components and grain sizes were prepared. Abundant two-phase interfaces with higher interface density are generated inside the Ni₃Se₄/NiSe₂-1 induced by much smaller nanograins in comparison with the Ni₃Se₄/NiSe₂-2, so that significant charge redistribution and faster electrons/Li⁺ ions transfer kinetics are achieved within the selenides, which are proved by the mutual verification of experiment and theoretical analysis. Benefitting from this optimized heterointerfaces, the Ni₃Se₄/NiSe₂@C-1 electrode manifests reduced polarization, superior rate capability, and prolonged cyclic stability (621.3 mAh g^-1 at 1 A g^-1 for 1000 cycles; 362.3 mAh g^-1 at 4 A g^-1 for 2000 cycles) with respect to the Ni₃Se₄/NiSe₂@C-2, as well as excellent performance in LiCoO₂//Ni₃Se₄/NiSe₂@C-1 full cell. Detailed electrochemical analysis confirmed rapid electrons/Li⁺ diffusion rates and more pseudocapacitive energy for the Ni₃Se₄/NiSe₂@C-1. Therefore, the Ni₃Se₄/NiSe₂@C-1 showcases superior hydrogen evolution reaction (HER) and lithium storage performance. This work demonstrates the significance of interface modulation to boost the electrochemical performance of multiphase heterostructures for energy storage and conversion.