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Low-cost and highly electroactive nickel-based materials are important electrodes for the development of supercapacitors. The precise modulation of the morphology and microstructure has been a crucial measure to further enhance the electrochemical performance. Herein, a three-dimensional porous nanocage NixS6/Ni(OH)2 hybrid formed by NixS6 nanoparticles anchored on Ni(OH)2 nanoflakes was creatively synthesized via a simple and scalable approach, which was based on two-time ion exchange reactions of the Mg(OH)2 precursor. Significantly, in asymmetric supercapacitors, the NixS6/Ni(OH)2 hybrid exhibits a high specific capacitance of 2726 F g−1 at a current density of 1 A g−1 and an excellent energy density of 31.31 Wh kg−1 at a power density of 62.56 W kg−1, which are superior to those of the currently reported nickel sulfide electrode materials. Compared with the nanoflower-like Mg(OH)2 and Ni(OH)2 precursors, the NixS6/Ni(OH)2 hybrid possesses hollow, abundant porous morphology and better electrical conductivity, which could provide a large contact surface area, shorter ion diffusion path and excellent charge transport, resulting in a dramatic improvement in electrochemical performance, making the NixS6/Ni(OH)2 hybrid a superb cathode material for supercapacitors. [ABSTRACT FROM AUTHOR]

A series of novel transition metal ion-substituted Zn 1- x A x WO 4 (A = Co, Mn, and Fe, 0 < x ≤ 0.1) inorganic pigments with blue, yellow, brown, and pale green colors have been prepared by a solution combustion method and exhibit extremely high near-infrared reflectance ( R > 85%). X-ray energy-dispersive spectroscopy analysis makes it clear that transition metal ions have already been incorporated into the host ZnWO 4 lattice and do not change the lattice's initial wolframite structure. The optical absorption spectrum in the UV region of the ZnWO 4 pigment calcined at 800 °C for 3 h is a ligand-to-metal charge transfer from O 2p nonbonding orbits to antibonding W 5d orbits. On account of the doping Co 2+ (3d 7 ), Mn 2+ (3d 5 ), and Fe 3+ (3d 5 ) transition metal ions, these chromophore ions have occupied the distorted octahedral site of Zn 2+ , leading to d-d transition and metal-to-metal charge transfer from the occupied 3d orbits of A 2+ to unoccupied W 5d orbits in UV and visible ranges and generating some bright colors. Significantly, these inorganic pigments are also endowed with excellent thermal and chemical stability and are conducive to harsh working conditions. All of the analysis results have offered some design strategies for various colorful inorganic pigments with high near-infrared reflectance.