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Development of electrode materials with well-defined architectures is a fruitful and profitable approach for achieving highly-efficient energy storage systems. A molecular-scale hybrid system is presented based on the self-assembly of CoNi-layered double hydroxide (CoNi-LDH) monolayers and the conducting polymer (poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate), denoted as PEDOT:PSS) into an alternating-layer superlattice. Owing to the homogeneous interface and intimate interaction, the resulting CoNi-LDH/PEDOT:PSS hybrid materials possess a simultaneous enhancement in ion and charge-carrier transport and exhibit improved capacitive properties with a high specific capacitance (960 F g-1 at 2 A g-1) and excellent rate capability (83.7% retention at 30 A g-1). In addition, an in-plane supercapacitor device with an interdigital design is fabricated based on a CoNi-LDH/PEDOT:PSS thin film, delivering a significantly enhanced energy and power output (an energy density of 46.1 Wh kg-1 at 11.9 kW kg-1). Its application in miniaturized devices is further demonstrated by successfully driving a photodetector. These characteristics demonstrate that the molecular-scale assembly of LDH monolayers and the conducting polymer is promising for energy storage and conversion applications in miniaturized electronics. [ABSTRACT FROM AUTHOR]

A hierarchical nanostructure composed of NiMn-layered double hydroxide (NiMn-LDH) microcrystals grafted on carbon nanotube (CNT) backbone is constructed by an in situ growth route, which exhibits superior supercapacitive performance. The resulting composite material (NiMn-LDH/CNT) displays a three-dimensional architecture with tunable Ni/Mn ratio, well-defined core-shell configuration, and enlarged surface area. An electrochemical investigation shows that the Ni3Mn1-LDH/CNT electrode is rather active, which delivers a maximum specific capacitance of 2960 F g-1 (at 1.5 A g-1), excellent rate capability (79.5% retention at 30 A g-1), and cyclic stability. Moreover, an all-solid-state asymmetric supercapacitor (SC) with good flexibility is fabricated by using the NiMn-LDH/CNT film and reduced graphene oxide (RGO)/CNT film as the positive and negative electrode, respectively, exhibiting a wide cell voltage of 1.7 V and largely enhanced energy density up to 88.3 Wh kg-1 (based on the total weight of the device). By virtue of the high-capacity of pseudocapacitive hydroxides and desirable conductivity of carbon-based materials, the monolithic design demonstrated in this work provides a promising approach for the development of flexible energy storage systems. [ABSTRACT FROM AUTHOR]

Hierarchical MgFe-layered double hydroxide (LDH) microspheres with tunable interior structure are synthesized by a facile and cost-effective surfactant-templated method. Scanning and transmission electron microscopy images reveal that the obtained microspheres display a three-dimensional architecture with hollow, yolk−shell and solid interior structure, respectively, with continuous changes in specific surface area and pore-size distribution. Moreover, the hollow MgFe-LDH microspheres exhibit excellent electrocatalytic oxidation of ethanol in alkaline fuel cell, including high activity, long-term durability and cycling stability, owing to the significantly improved faradaic redox reaction and mass transport. Therefore, this work provides a promising approach for the design and synthesis of structure tunable materials with largely enhanced ethanol electrooxidation behavior, which can be potentially used in noble metal-free alkaline fuel cells. [ABSTRACT FROM AUTHOR]

Supported nickel nanoparticles with high dispersion have been prepared by partial reduction of NiAl-layered double hydroxide (NiAl-LDH) precursors, which exhibit significant electrocatalytic behavior towards glucose. XRD and XPS results confirm that the nickel nanoparticles are successfully synthesized. TEM images reveal that the nickel nanoparticles are highly dispersed in the NiAl-LDH matrix with a size of 6±0.3 nm. The resulting nanocomposite modified electrode displays significant electrocatalytic performance to glucose with a broad linear response range (8.0×10−5-2.0×10−3 M), low detection limit (3.6 µM), high sensitivity (339.2 µA/mM), selectivity and excellent reproducibility as well as repeatability. [ABSTRACT FROM AUTHOR]

Abstract: A facile enzyme-free hydrogen peroxide electrochemical sensor was fabricated based on multilayer ultrathin film containing Naphthol green B anions (NGB) and exfoliated nanosheets of Co–Al layered double hydroxide (LDH) via layer-by-layer self-assembly technique. The X-ray diffraction pattern indicates the superlattice structure of the film with repeating distance of 4.15nm; SEM and AFM images show that the film surface is continuous and uniform. The electrochemical behavior of the ultrathin film was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The ultrathin film modified electrode shows a fast direct electron transfer for the Co2+/Co3+ redox couple with ΔE =14mV in 0.1M NaOH solution. Furthermore, the modified electrode displays a significant electrocatalytic performance for H2O2 with Michaelis–Menten constant . The anodic peak current increased linearly with the concentration of H2O2 from 8.0×10−6 to 1.8×10−4 M with a low detection limit of 9.0×10−7 M. The NGB/LDH ultrathin film was demonstrated as a feasible electrochemical sensor for detection of H2O2 with rapid response, high stability, good reproducibility and excellent selectivity. [Copyright &y& Elsevier]

A well‐designed hierarchical nanostructure composed of NiMn‐layered double hydroxide (NiMn‐LDH) microcrystals grafted on a carbon nanotube (CNT) backbone is constructed by M. Wei and co‐workers using an in situ growth route, which shows superior supercapacitive performance. On page 2938, an all‐solid‐state asymmetric supercapacitor (SC) with good flexibility is fabricated using the NiMn‐LDH/CNT film and reduced graphene oxide (RGO)/CNT film as the positive and negative electrodes, respectively. [ABSTRACT FROM AUTHOR]

Abstract: A novel inorganic–organic composite ultrathin film was fabricated by layer-by-layer assembly of naphthol green B (NGB) and layered double hydroxides (LDHs) nanoplatelets, which shows remarkable electrocatalytic behavior for oxidation of ascorbic acid. LDHs nanoplatelets were prepared using a method involving separate nucleation and aging steps (particle size: 25±5nm; aspect ratio: 2–4) and used as building blocks for alternate deposition with NGB on indium tin oxide (ITO) substrates. UV–vis absorption spectroscopy and XRD display regular and uniform growth of the NGB/LDHs ultrathin film with extremely c-orientation of LDHs nanoplatelets (ab plane of microcrystals parallel to substrates). A continuous and uniform surface morphology was observed by SEM and AFM image. The film modified electrode displays a couple of well-defined reversible redox peaks attributed to Fe2+/Fe3+ in NGB (ΔE p =68mV and I a /I c =1.1). Moreover, the modified electrode shows a high electrocatalytic activity towards ascorbic acid in the range 1.2–55.2μM with a detection limit of 0.51μM (S/N=3). The Michaelis–Menten constant was calculated to be . [Copyright &y& Elsevier]

Core–shell layered double hydroxide microsphereswith tunable interior architecturehave been synthesized by a facile and cost-effective in situgrowth method. The SEM and TEM images revealed that the obtainedmicrospheres display a three-dimensional architecture with core–shell,yolk–shell, and hollow interior structure respectively, withcontinuous changes in specific surface area and pore-size distribution.Moreover, the hollow NiAl-LDH microspheres exhibit excellent pseudocapacitanceperformance, including high specific capacitance and rate capability,good charge/discharge stability and long-term cycling life, owingto the greatly improved faradaic redox reaction and mass transfer.Therefore, this work provides a promising approach for the designand synthesis of structure tunable materials with largely enhancedsupercapacitor behavior, which can be potentially applied in energystorage/conversion devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Photoreduction CO 2 to syngas evolution could be achieved by CoMgAl-LDH. • The highl high dispersion of Co and hydroxyl defects contributed the photoactivity. • CoMgAl-LDH exhibited excellent performance under high wavelength of 650 nm. The conversion of solar energy to chemical fuels by CO 2 photoreduction reaction (CO 2 PR) is a promising pathway to alleviate rapid energy consumption crisis. Nevertheless, only a few systems have been reported so far by applying solar energy in visible light region in particular high wavelength (such as λ ≥ 650 nm). Herein, we report an efficient 650 nm-induced CO 2 photocatalytic reduction system to syngas by introducing Co into MgAl-layered double hydroxide (CoMgAl-LDH) nanosheets in conjunction with Ru(bpy) 3 ]Cl 2 ·6H 2 O as photosensitizer, in which [Ru(bpy) 3 ]Cl 2 ·6H 2 O could be activated to generate photogenerated electrons which further transfer to surface of CoMgAl-LDH for CO 2 reduction. Under irradiation >400 nm, the CoMgAl-LDH nanosheets showed excellent CO 2 conversion with TOF of 11.57 h−1, 3 times higher than that of CoAl-LDH. Most importantly, up to monochromatic irradiation wavelength at 650 nm, the CoMgAl-LDH nanosheets still displayed optimized syngas evolution rate, with CO rate of 0.35 μmol·h−1 with quantum yield of 0.86%. Furthermore, as evidenced by X-ray absorption fine structure spectroscopy and high-resolution synchrotron X-ray powder diffraction, the proper introduction of Co promoted its dispersion on the laminate of LDH. The suitable dispersion of Co active sites into LDH nanosheets facilitates the transportation of photo-generated electrons to further promote catalytic activity for reaction. This work paves a potential way for CO 2 PR to syngas under wavelength irradiation up to 650 nm. [ABSTRACT FROM AUTHOR]