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Among the electrode materials for supercapacitors (SCs), metal-organic framework (MOFs) is attracting huge research interest as a new type of energy storage electrode materia. However, due to their poor conductivity and stability, the practical application of original MOFs in the field of energy storage has been greatly hindered. Here, we demonstrate a special core-shell structure, which the synergistic action of NiCo2O4 and Ni-MOF forms a tight conductive network that speeds up electron transport and larger specific surface area, more active sites were obtained and mechanical stability that indicates its outstanding long life. The test results show that it has a high specific capacity of 4.23 F cm–2 at 5 mA cm–2, and the capacity retention rate is maintained at 97.5% after 8000 cycles. In addition, an asymmetric supercapacitor device, using NiCo2O4@Ni-MOF and activated carbon (AC) as anode and cathode, has a high specific capacity of 3.21 F cm–2 at 5 mA cm–2 and excellent cycling performance (83.8% retention over 8000 cycles at 10 mA cm–2). Our work demonstrates the possibility of using novel structured Ni-MOF-based hybrid arrays as electrodes for SCs with enhanced electrochemical performance compared to Ni-MOF and NiCo2O4, providing a reliable prospect for flexible energy storage devices. [ABSTRACT FROM AUTHOR]

The surface plasmon resonance (SPR)‐generated electric field (E‐field) intensities around a Ag nanocube (NC) before and after it is covered by a BaTiO3 (BTO) layer (BTO@Ag NC) were calculated. It was observed that the theoretical E‐field intensities were reduced on BTO@Ag NCs, thus suggesting inferior catalytic activities under visible light illumination. However, BTO@Ag NCs experimentally displayed better photocatalytic performance than that of Ag NCs under illumination at 633 nm, both in ambient argon (Ar) and in ambient air, where p‐aminothiophenol (PATP) molecules were used to probe the conversion. The mechanism can be attributed to the surface polarization of the BTO layer trigged by a SPR effect of the Ag core. The oscillation of free electrons in the Ag core aroused appearance of surface polarization charge on the ferroelectric (FE) BTO surface, which resulted in the enhanced catalytic properties of BTO@Ag NCs. Therefore, our finding may provide a novel method to enhance visible‐light responsive photocatalytic activity of wide bandgap FE materials by depositing them on plasmonic metal nanostructures. [ABSTRACT FROM AUTHOR]

Phase change materials can enable temperature self-regulation due to their drastic changes in optical properties accompanying the phase transition. Significant reduction of the optical absorption after the transition is the key ingredient for an enhanced regulating performance. However, the absorptivity of unpatterned vanadium dioxide (VO2) thin films can hardly be reduced after phase transition at visual-to-infrared band. In this work, we combine the direct binary search (DBS) and particle swarm optimization (PSO) algorithms for an optimized design of temperature self-regulating nano-photonic devices on VO2 thin films. For a given incident wavelength, a pixelated structure is firstly inverse-designed by the DBS algorithm which maximizes the absorption contrast before and after the transition. To overcome fabrication challenges as pixel size is at deep sub-wavelength scale, the pixelated structure can then be replaced by geometric shapes which are more tractable in manufacturing processes. The geometrical parameters are optimized by the PSO algorithm where our optimized device brings the absorptivity down to 33% after the transition. These results provide an effective way for the inverse design of optimized nano-photonic structures based on phase change materials. [ABSTRACT FROM AUTHOR]

In this paper, NiMoO4@CoWO4 core–shell nanostructures have been synthesized by a hydrothermal process and annealing. Structural characterization and compositional analysis of the as-prepared NiMoO4@CoWO4 nanocomposites were performed using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, cyclic voltammetry, galvanostatic charge–discharge cycling, and electrochemical impedance spectroscopy. Here, NiMoO4@CoWO4 nanostructures were designed and synthesized on Ni foam. NiMoO4 nanorods would provide electron "superhighways" for charge storage and delivery, which could provide an effective electrical connection to the CoWO4 electrode material. In addition, the open space between these nanosheets can increase the active sites and the contribution of capacitive effects. Finally, NiMoO4@CoWO4 directly grown on Ni foam could avoid the "dead" volume caused by the tedious process of mixing active materials with polymer binders/conductive additives. As expected, NiMoO4@CoWO4 exhibited high specific capacity, good rate performance and excellent electrochemical stability. The results show that NiMoO4@CoWO4 exhibited a high specific capacity at a current density of 5 mA cm−2 and splendid electrochemical stability (88.5% retention after 4000 cycles). The great electrochemical performance could be ascribed to the unique core–shell architecture and the synergistic effect from the NiMoO4 nanorods and CoWO4. [ABSTRACT FROM AUTHOR]

As a multifunctional material, TiO2 shows excellent performance in catalytic degradation and lithium-ion storage. However, high electron-hole pair recombination, poor conductivity, and low theoretical capacity severely limit the practical application of TiO2. Herein, TiO2 nanotube (TiO2 NT) with a novel double-layer honeycomb structure were prepared by two-step electrochemical anodization. Honeycombed TiO2 NT arrays possess clean top surfaces and a long-range ordering, which greatly facilitates the preparation of high-performance binary and ternary materials. A binary TiO2 nanotube@Au nanoparticle (TiO2 NT@Au NP) composite accompanied by appropriately concentrated and uniformly distributed gold particles was prepared in this work. Interestingly, the TiO2 nanotube@Au nanoparticle (TiO2 NT@Au NP) composites not only showed the excellent catalytic degradation effect of methylene blue, but also demonstrated large lithium-ion storage capacity (310.6 μAh cm−2, 1.6 times of pristine TiO2 NT). Based on the realization of the controllable fabrication of binary TiO2 nanotube@MoS2 nanosheet (TiO2 NT@MoS2 NS) composite, ternary TiO2 nanotube@MoS2 nanosheet@Au nanoparticle (TiO2 NT@MoS2 NS@Au NP) composite with abundant defects and highly ordered structure was also innovatively designed and fabricated. As expected, the TiO2 NT@MoS2 NS@Au NP anode exhibits extremely high initial discharge specific capacity (487.4 μAh cm−2, 2.6 times of pristine TiO2 NT) and excellent capacity retention (81.0%). [ABSTRACT FROM AUTHOR]