Gas and moisture barrier materials are of crucial importance in various application fields, including food/drug packaging and encapsulation of electronic devices. Herein, a dual-barrier film to gas and water vapor was fabricated by a facile and cost-effective spin-coating of amphiphilic surfactant (Tween 80) modified LDH nanoplatelets (denoted as LDH-80) and polydimethylsiloxane (PDMS). The resultant (LDH-80/PDMS)15 film exhibits low O2 and H2O transmission rates with ∼0.701 and ∼0.049 cm3 m-2 d-1 atm-1, respectively, smaller than those for most of the reported barrier materials. The remarkable barrier properties are ascribed to the prolonged diffusion length for gas permeation and improved inorganic-organic interfacial compatibility between LDH-80 and PDMS. Taking advantage of this unique dual-barrier property, an aluminum foil substrate coated with (LDH-80/PDMS) n film displays an excellent anti-corrosion effect due to the inhibition of oxygen-consuming corrosion, which enables the (LDH-80/PDMS) n films to be promising candidates in metal surface protection.

A supercapacitor based on hierarchical OH−-containing CoAl layered double hydroxide (LDH) arrays exhibits excellent energy and power output, especially an ultrahigh-rate-capability, which is attributed to the self-generated electrolyte (OH−) reservoir in the LDH gallery.

Recently, layered double hydroxides (LDHs) have attracted extensive attention in the field of energy storage and conversion, and an in-depth understanding of their semiconducting properties is rather limited. In this work, the electronic properties (band structure, density of states (DOS), and band edge placement) of (MMIII)-M-II-LDHs (M-II = Mg, Co, Ni and Zn; M-III = Al and Ga) were studied in detail. The thermodynamic mechanism toward oxygen evolution reaction (OER) was investigated by using the density functional theory plus U (DFT + U) method. The calculation results of band structure indicate that Mg and Zn-based LDHs (band gap energies larger than 3.1 eV) are ultraviolet responsive, while Co and Ni-based LDHs are responsive to visible light (band gap energies less than 3.1 eV). The DOS calculations reveal that the photogenerated hole localizes on the surface hydroxyl group of LDHs, facilitating the oxidization of a water molecule without a long transportation route. The band edge placements of (MMIII)-M-II-LDHs show that NiGa-, CoAl-, ZnAl-, and NiAl-LDHs have a driving force (0.965 eV, 0.836 eV, 0.667 eV, and 0.426 eV, respectively) toward oxygen evolution. However, the thermodynamic mechanism of these four LDHs reveal that only CoAl-LDH can overcome the reaction barrier (0.653 eV) via the driving force of photogenerated hole (0.836 eV). Experimental observations of MgAl-, CoAl-, and ZnAl-LDHs further prove that only CoAl-LDH is an efficient oxygen evolution photocatalyst (O-2 generation rate: 973 mu mol h(-1) g(-1)), agreeing well with the theoretical prediction. Therefore, this work provides an effective theoretical and experimental combined method for screening possible photocatalysts, which can be extended to other semiconductor materials in addition to LDHs.

TiO2@CoAl‐layered double hydroxide (LDH) core–shell nanospheres are fabricated via hydrothermal synthesis of TiO2 hollow nanospheres followed by in situ growth of CoAl‐LDH shell, which exhibit an extraordinarily high photocatalytic activity toward oxygen evolution from water oxidation. The O2 generation rates of 2.34 and 2.24 mmol h−1 g−1 are achieved under full sunlight (>200 nm) and visible light (>420 nm), respectively, which are among the highest photocatalytic activities for oxygen production to date. The reason is attributed to the desirable incorporation of visible‐ light‐active LDH shell with UV light‐responsive TiO2 core for promoted solar energy utilization. Most importantly, the combined experimental results and computational simulations reveal that the strong donor–acceptor coupling and suitable band matching between TiO2 core and LDH shell facilitate the separation of photoinduced electron‐hole pairs, accounting for the highly efficient photocatalytic performance. Therefore, this work provides a facile and cost‐effective strategy for the design and fabrication of hierarchical semiconductor materials, which can be applied as photocatalyst toward water splitting and solar energy conversion.

Electrochromic materials are the most important and essential components in an electrochromic device. Herein, we fabricated high-performance electrochromic films based on exfoliated layered double hydroxide (LDH) nanosheets and Prussian blue (PB) nanoparticles via the layer-by-layer assembly technique. X-ray diffraction and UV-vis absorption spectroscopy indicate a periodic layered structure with uniform and regular growth of (LDH/PB)n ultrathin films (UTFs). The resulting (LDH/PB)n UTF electrodes exhibit electrochromic behavior arising from the reversible K(+) ion migration into/out of the PB lattice, which induces a change in the optical properties of the UTFs. Furthermore, an electrochromic device (ECD) based on the (LDH/PB)n-ITO/0.1 M KCl electrolyte/ITO sandwich structure displays superior response properties (0.91/1.21 s for coloration/bleaching), a comparable coloration efficiency (68 cm(2) C(-1)) and satisfactory optical contrast (45% at 700 nm), in comparison with other inorganic material-based ECDs reported previously. Therefore, this work presents a facile and cost-effective strategy to immobilize electrochemically active nanoparticles in a 2D inorganic matrix for potential application in displays, smart windows and optoelectronic devices.

Organic–inorganic hybrid films are fabricated via an alternate assembly of a chitosan (CTS) polymer and hierarchical layered double hydroxide (H-LDH), which exhibit tremendous oxygen barrier properties with high stability as well as long-term maintenance.

Transparent and flexible gas-barrier materials have shown broad applications in electronics, food, and pharmaceutical preservation. Herein, we report ultrahigh-gas-barrier films with a brick-mortar-sand structure fabricated by layer-by-layer (LBL) assembly of XAl-layered double hydroxide (LDH, X=Mg, Ni, Zn, Co) nanoplatelets and polyacrylic acid (PAA) followed by CO2 infilling, denoted as (XAl-LDH/PAA)n-CO2. The near-perfectly parallel orientation of the LDH "brick" creates a long diffusion length to hinder the transmission of gas molecules in the PAA "mortar". Most significantly, both the experimental studies and theoretical simulations reveal that the chemically adsorbed CO2 acts like "sand" to fill the free volume at the organic-inorganic interface, which further depresses the diffusion of permeating gas. The strategy presented here provides a new insight into the perception of barrier mechanism, and the (XAl-LDH/PAA)n-CO2 film is among the best gas barrier films ever reported.

A NiAl layered double hydroxide (LDH)@carbon nanoparticles (CNPs) hybrid electrode was fabricated via a facile and cost-effective approach and displays excellent pseudocapacitive behavior in asymmetric supercapacitors.

Hybrid films were fabricated via layer-by-layer assembly of layered double hydroxide (LDH) nanoplatelets and poly(sodium styrene-4-sulfonate) (PSS) followed by subsequent permeation of poly(vinyl alcohol) (PVA), which show excellent oxygen barrier performance with humidity-triggered self-healing capability.

A smart supercapacitor was fabricated by loading a thermosensitive polymer P(NIPAM-co-SPMA) onto the surface of NiAl-layered double hydroxide (LDH) nanowalls grown on a flexible Ni foil substrate, which displays temperature-triggered on-off ion channels for controlling the electrochemical behavior.

Roundness error is a shape error that affects the performance of mechanical parts, especially rotary motion performance. Its measurement generally needs to be carried out in the normal section of the work-piece. Articulated coordinate measuring machine is a manual in-situ measuring instruments widely applied in production line, which cannot execute measurement strictly in a cross-section. This paper reports an algorithm for evaluating the roundness error from the measured data by articulated coordinate measuring machine. Firstly a cylindrical surface is fit from the measurement data that disperses on the surface of the mechanical part under test. Secondly an evaluation plane is selected according to least squares method. The roundness error is calculated through projecting the measured points into the plane and in conformity with least square method. The evaluation result is verified by comparing with the result given by a Descartes coordinate measurement machine. Furthermore, the contribution of various measured points to the roundness error is estimated by way of region division. Experimental results show that the evaluation method is reliable and effective.