Synthesis of Mn-CoO/Ni3S2/Ni12P5 composites with tailored microelectronic structure in nickel foam for high-efficiency supercapacitors.

Abstract

The rational design of heterointerfaces, particularly those between sulfides and phosphides, represents a powerful yet challenging strategy for enhancing supercapacitor electrode performance by tailoring electronic structures. In this work, we fabricated a sulfide-phosphide heterostructure (Ni3S2/Ni12P5) and observed that it induces significant electronic structure modulation, which substantially improves electrochemical properties. Specifically, we constructed a unique pine-tower-like Ni12P5 layer on nickel foam via low-temperature phosphidation, followed by in situ growth of Mn-CoO/Ni3S2 composites on this layer using a one-step hydrothermal process, forming a well-defined three-dimensional flower-like architecture. Experimental characterizations confirm the successful formation of the heterojunction, while density functional theory (DFT) simulations reveal a directional electron transfer of 0.246e- from Ni3S2 to Ni12P5 at the interface, reducing the interfacial resistance by approximately 80%. This electronic structure modulation, arising directly from the sulfide-phosphide heterointerface, facilitates charge transfer and inhibits nanocrystal coarsening during cycling, thereby enhancing structural stability. The optimized electrode delivers an ultrahigh areal capacitance of 21.85 F cm-2 at 1 mA cm-2 and retains 85.7% of its capacity after 10 000 cycles at 15 mA cm-2. Furthermore, the assembled hybrid supercapacitor achieves a high energy density of 111.75 Wh kg-1 (26.82 Wh m-2), a power density of 1999.73 W kg-1 (479.93 W m-2), and an outstanding cycling stability of 99.6% capacity retention over 10 000 cycles. This work elucidates the critical role of heterointerfacial electronic engineering, specifically the sulfide-phosphide heterostructure, in regulating charge storage dynamics, providing a valuable design principle for advanced energy storage materials.