Promoting high-energy supercapacitor performance over NiCoP/N-doped carbon hybrid hollow nanocages via rational architectural and electronic modulation

Delicately engineering nano-architecture and electronic structure can assist in constructing the high-performance electrode materials for high-energy supercapacitor. Herein, a hollow nanocage is in-situ introduced into bimetallic phosphide-based materials via a green self-template strategy at room temperature. The homogeneous hollow configuration that N-doped carbon confined NiCoP nanoparticles hybrid nanocages (NiCoP/NC) is harvested via elaborately manipulating the physicochemical properties at the molecular level. This well-defined hollow geometry ensures the convenient electrolyte access for electroactive sites, thus facilitating the electrochemical activities. X-ray photoelectron spectroscopy reveals the electronic interaction among Ni, Co and P elements, which can induce an appropriate electric-field environment favors for the charge-carriers immigration. Density-functional-theory simulations indicate the increased electronic states of d-orbital around the Fermi level, which benefit for lower OH- adsorption energies (-3.80 eV), therefore resulting the faster electrochemical dynamics. Accordingly, as-prepared NiCoP/NC electrode achieves superb rate-capability (1127 and 873F g(-1) at 1 and 16 A g(-1), respectively) and long-term durability (75.5% retention after 8000 cycles). Furthermore, a hybrid supercapacitor based on NiCoP/NC cathode demonstrates an ultra-high energy density (52.5 Wh kg(-1)), outperforming similar hybrid devices. Our studies successfully give an insight into the relationship between nanomorphology, electronic modulation and electrochemical performance, which can provide some guidance for garnering a desirable electrode material.