Nickel Dichalcogenide Hollow Spheres: Controllable Fabrication, Structural Modification, and Magnetic Properties

摘要

Morphology-dependent properties of nano-/microspheres with hollow interiors have attracted immense attention because of the unique properties and potential technological applications in various fields, such as electronics, optoelectronics, selective catalysis, controlled release, and delivery, etc.~([1]) Inspired by the excellent properties, the study on the fabrication of transition-metal dichalcogenides with desired morphologies is continually being intensified.~([2]) In particular, nickel dichalcogenides (such as NiS_2, NiSe_2 and NiTe_2) have become the focus in recent years due to their novel electric and magnetic properties and important technological applications in various fields. It is well known that NiS_2 is of particular interest as a Mott–Hubbard insulator with anomalous antiferromagnetic long-range order and a metal-insulator transitional body in NiS_(2-x)Se_x, whereas NiSe_2 is a typical Pauli paramagnet with metallic conductivity and, therefore, is suitable as a storage energy material for rechargeable lithium batteries.~([3]) More importantly, NiSe_2 can also be applied as the prominent Pt-free electrocatalyst for dye-sensitized solar cells (DSSCs), which shows better catalytic activity in the reduction of triiodide than Pt electrode.~([4]) Furthermore, NiTe_2 is a promising back contact to CdTe/CdS solar cells with exceeding 10% conversion efficiencies.~([5]) A variety of chemical and physicochemical methods, such as solid-state synthesis, elemental direct reaction, and mechanical alloying have been used to fabricate nickel dichalcogenides; nevertheless, there is barely a report about the synthesis of NiS_2, NiSe_2, and NiTe_2 hollow spheres up to now, partly due to the difficulties in fabricating transition-metal dichalcogenides with regular morphologies.~([6])