Improving Charge Storage of Biaxially-Oriented Polypropylene under Extreme Electric Fields by Excimer UV Irradiation.

Biaxially-oriented polypropylene (BOPP) is one of the most commonly used materials for film-based capacitors for power electronics and pulsed power systems. To address the pressing issue of performance-limiting loss under extreme electric-fields, here a one-step, high-throughput, and environment-friendly process based on very low-dose ultra-violet irradiation from KrCl (222 nm) and Xe2 (172 nm) excimer is demonstrated. The performance of commercial BOPP is boosted in terms of withstanding electric-field extremes (Weibull breakdown strength 694 to 811 V µm-1 by 17% at 25 °C and 428 to 651 V µm-1 by 52% at 120 °C), discharged energy density, and conduction losses. Importantly, the depth profile of space charge is precisely measured in situ with a high resolution of 500 nm by laser induced pressure pulse. Consequently, the space charge effect and electric-field distortion are reduced and related to the improved polymer films. It is demonstrated that energetic UV photons act as scissors for BOPP chains and dissociate oxygen molecules leading to the more thermally stable oxygen-containing structures, as deep traps to impede charge migration. This work provides a promising approach to produce polymers with customized microscopic characteristics that is compatible with the assembly lines of polymer-based capacitors.

Flexible 3D Substrate of Ag Nanoparticle-Loaded Carbon Aerogels with Outstanding Surface-Enhanced Raman Scattering Performance.

Surface-enhanced Raman scattering (SERS), an ultra-sensitive and non-destructive analytic technique, has attracted wide attention from the scientific community. Despite its rapid development, limited hotspots on the SERS substrates have restricted their potential in practical applications. Herein, we developed a facile method to fabricate a flexible three-dimensional (3D) SERS substrate composed of silver nanoparticles (Ag NPs)-loaded carbon aerogels (CAs). Such a flexible Ag NPs/CAs substrate exhibited numerous hotspots, which can facilely be adjusted not only by tuning the density of Ag NPs but also by controlling the bending degree of the flexible substrate. In addition, the influence of hotspots on the local electric field enhancement was investigated by theoretical calculations. Moreover, the 3D network structure of the CAs with a large specific surface area and strong adsorption ability can improve the capture of target molecules. Consequently, the optimal Ag NPs/CAs substrate has a low detection limit of 10-12 M for rhodamine 6G molecules as well as good repeatability. Furthermore, based on the good performance of SERS detection of the Ag NPs/CAs substrate, it can also be practically used for the detection of thiram molecules on the surface of cherry tomatoes. Such a flexible 3D Ag NPs/CAs substrate has great potential for practical environmental monitoring applications.

Mass-determining role in the electrophoretic separation of colloidal plasmonic nanoparticle oligomers.

Gel electrophoresis techniques have been commonly applied in sieving plasmonic nanoparticle oligomers, while the intrinsic role in determining their phoresis velocity differences through the gel remains debatable. In this work, we explore the components and yield in each gel band after bundling two rationally designed types of nanoparticles in a system for electrophoretic separation. All results indicate that the mass property of plasmonic oligomers plays an essential role in determining their phoresis velocity divergences during separation. Further theoretical simulations reveal that the grounds for the mass-determining role stemmed from the random inelastic collisions among the oligomers and the gel-network microchannel. Moreover, under the guidance of such a mass-determining role, it is easy to achieve the direct electrophoretic separation of hetero-structured plasmonic dimers with high purity and high yield. This work will not only facilitate the precise nano-engineering of complex plasmonic oligomers with unique optical properties, but also might remove the obstacles toward their industrial manufacture with high purity.

Enhancing CO2 methanation over a metal foam structured catalyst by electric internal heating.

We develop an electric internal heating method based on a Ni-foam structured catalyst for CO2 methanation, in which the Joule heat generated by electric current passing through the catalyst drives the reaction. Compared with the conventional external heating method, EIH significantly enhances the catalytic activity and anti-poisoning ability of the catalyst.

Novel core-shell-like nanocomposites xCu@Cu2O/MgAlO-rGO through an in situ self-reduction strategy for highly efficient reduction of 4-nitrophenol.

A series of novel hierarchical nanocomposite catalysts xCu@Cu2O/MgAlO-rGO were fabricated by calcination of CuxMg3-xAl-LDH/rGO precursors (LDH: layered double hydroxide, rGO: reduced graphene oxide, and x = 0.5, 1.0, and 1.5), obtained by a facile citric acid-assisted coprecipitation route, under a N2 flow upon in situ self-reduction of lattice atomic-dispersed Cu2+ by rGO. Systematic characterization reveals highly dispersed core-shell-like Cu@Cu2O nanoparticles near the border between vertically interconnected mixed oxide MgAlO nanoplates and rGO layers. All the obtained catalysts show extraordinary catalytic performances for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) at room temperature. The 1.0Cu@Cu2O/MgAlO-rGO shows the highest activity for complete conversion of 4-NP with an apparent rate constant (kapp) of 55.3 × 10-3 s-1, a normalized rate constant (knor) of 14 497 s-1 g-1 on an active Cu content, and an unprecedented recycling stability for 25 successive cycles, which are superior to those of the recently reported Cu- and Co-based metal nanoparticles and even compared favourably with those of the most active noble metal catalysts. The superior activity of 1.0Cu@Cu2O/MgAlO-rGO can be attributed to the highly dispersed core-shell-like Cu@Cu2O nanoparticles and the greatly enhanced four-phase synergistic effect among Cu, Cu2O, MgAlO and rGO upon calcination. Moreover, 1.0Cu@Cu2O/MgAlO-rGO shows an excellent efficiency in the fixed bed system for the treatment of simulated industrial effluents containing nitrophenols and organic dyes. The present cost-effective, highly efficient and reusable non-noble metal nanocatalyst would open a new pathway for future water remediation.

Nanosheet Array-Like Palladium-Catalysts Pdx/rGO@CoAl-LDH via Lattice Atomic-Confined in Situ Reduction for Highly Efficient Heck Coupling Reaction.

A series of novel nanosheet array-like catalysts Pdx/rGO@CoAl-LDH (x = 0.0098-1.9, refers to Pd loading in wt % on ICP, rGO: reduced graphene oxide, LDH: layered double hydroxide) were first prepared via a simple and green lattice atomic-confined in situ reduction of oxidative Pd precursors by the evenly atomic-dispersed reductive Co2+ sites on LDH layers of a nanohybrid rGO@CoAl-LDH with hexagonal LDH nanoplates (∼73 × 7 nm) interdigitated vertical to the surfaces of rGO layer in both sides, fabricated through a simple citric acid-assisted aqueous-phase coprecipitation method. The as-obtained Pd catalysts possess clean Pd nanoclusters (NCs) with tunable sizes in 1.3-1.8 nm on varied Pd loadings. All the Pdx/rGO@CoAl-LDH catalysts show excellent activities for the Heck reaction, and the Pd0.0098/rGO@CoAl-LDH with the ultrafine Pd NCs of 1.3 ± 0.2 nm yields a maximum turnover frequency of 160 000 h-1 over a heterogeneous catalyst so far. The excellent activities can be attributed to the ultrasmall Pd NCs with high dispersion and clean Pd surfaces, increased electron transfer capacity and surface area, and remarkable Pd-CoAl-LDH-rGO three-phase synergistic effect of the present unique nanosheet array-like Pd NCs catalysts. Moreover, the catalyst Pd0.33/rGO@CoAl-LDH shows a broad range of substrate applicability and can be reused more than five runs without obvious loss of activity, giving the present catalysts long-term stability. These findings make the rGO@CoAl-LDH hybrid prepared by a facile and scalable synthesis route a universal green platform to support other noble or nonprecious metal NCs via lattice atomic-confined in situ reduction strategy to construct more desired heterogeneous catalysts.

Layered double hydroxide-based nanocarriers for drug delivery.

Biocompatible clay materials have attracted particular attention as the efficient drug delivery systems (DDS). In this article, we review developments in the use of layered double hydroxides (LDHs) for controlled drug release and delivery. We show how advances in the ability to synthesize intercalated structures have a significant influence on the development of new applications of these materials. We also show how modification and/or functionalization can lead to new biotechnological and biomedical applications. This review highlights the most recent progresses in research on LDH-based controlled drug delivery systems, focusing mainly on: (i) DDS with cardiovascular drugs as guests; (ii) DDS with anti-inflammatory drugs as guests; and (iii) DDS with anti-cancer drugs as guests. Finally, future prospects for LDH-based drug carriers are also discussed.

Layered double hydroxide supported gold nanoclusters by glutathione-capped Au nanoclusters precursor method for highly efficient aerobic oxidation of alcohols.

M3Al-layered double hydroxide (LDH, M = Mg, Ni, Co) supported Au nanoclusters (AuNCs) catalysts have been prepared for the first time by using water-soluble glutathione-capped Au nanoclusters as precursor. Detailed characterizations show that the ultrafine Au nanoclusters (ca. 1.5 ± 0.6 nm) were well dispersed on the surface of LDH with a loading of Au below ∼0.23 wt% upon synergetic interaction between AuNCs and M3Al-LDH. AuNCs/Mg3Al-LDH-0.23 exhibits much higher catalytic performance for the oxidation of 1-phenylethanol in toluene than Au/Mg3Al-LDH(DP) by the conventional deposition precipitation method and can be applied for a wide range of alcohols without basic additives. This catalyst can also be reused without loss of activity or selectivity. The AuNCs/M(= Ni, Co)3Al-LDH catalysts present even higher alcohol oxidation activity than AuNCs/Mg3Al-LDH. Particularly, AuNCs/Ni3Al-LDH-0.22 exhibits the highest activity (46 500 h(-1)) for the aerobic oxidation of 1-phenylethanol under solvent-free conditions attributed to its strongest Au-support synergy. The excellent activity and stability of AuNCs/M3Al-LDH catalysts render these materials promising candidates for green base-free selective oxidation of alcohols by molecular oxygen.