Cover Picture: A Diagonal Approach to Chemical Recycling of Carbon Dioxide: Organocatalytic Transformation for the Reductive Functionalization of CO2 (Angew. Chem. Int. Ed. 1/2012)

A Broadly Applicable Strategy for Entry into Homogeneous Nickel(0) Catalysts from Air-Stable Nickel(II) Complexes

A series of air-stable nickel complexes of the form L2Ni(aryl) X (L = monodentate phosphine, X = Cl, Br) and LNi(aryl)X (L = bis-phosphine) have been synthesized and are presented as a library of precatalysts suitable for a wide variety of nickel-catalyzed transformations. These complexes are easily synthesized from low-cost NiCl2·6H2O or NiBr2·3H2O and the desired ligand followed by addition of 1 equiv of Grignard reagent. A selection of these complexes were characterized by single-crystal X-ray diffraction, and an analysis of their structural features is provided. A case study of their use as precatalysts for the nickel-catalyzed carbonyl-ene reaction is presented, showing superior reactivity in comparison to reactions using Ni(cod)2. Furthermore, as the precatalysts are all stable to air, no glovebox or inert-atmosphere techniques are required to make use of these complexes for nickel-catalyzed reactions.

A general quantitative pH sensor developed with dicyandiamide N-doped high quantum yield graphene quantum dots

A general quantitative pH sensor for environmental and intracellular applications was developed by the facile hydrothermal preparation of dicyandiamide (DCD) N-doped high quantum yield (QY) graphene quantum dots (GQDs) using citric acid (CA) as the carbon source. The obtained N-doped GQDs have excellent photoluminesence (PL) properties with a relatively high QY of 36.5%, suggesting that N-doped chemistry could promote the QY of carbon nanomaterials. The possible mechanism for the formation of the GQDs involves the CA self-assembling into a nanosheet structure through intermolecular H-bonding at the initial stage of the reaction, and then the pure graphene core with many function groups formed through the dehydration between the carboxyl and hydroxyl of the intermolecules under hydrothermal conditions. These N-doped GQDs have low toxicity, and are photostable and pH-sensitive between 1.81 to 8.96, giving a general pH sensor with a wide range of applications from real water to intracellular contents.

Assembly of multivalent protein ligands and quantum dots: a multifaceted investigation

The development of multivalent protein ligands for nanoparticles lags behind that of multidentate polymers and small-molecule ligands largely because of a lack of thorough understanding of the interaction between nanoparticles and multimeric proteins. Guided by protein crystal structures, we have harnessed recombinant technology to develop a collection of mCherry fused multimeric proteins with different spatial distributions of the quantum dot (QD)-binding sequence, hexahistidine tag (histag). All of the proteins can behave as ligands to assemble with ZnS-CdSe QDs through metal-affinity-driven self-assembly. We have observed that protein shape and geometry greatly affect the stoichiometry and stability of their assemblies with QDs. We also demonstrate a peptide-induced structural transition of a nanobelt protein that preorganizes the QD-binding sites and effects a more efficient assembly with QDs. This work reports the first multifaceted investigation on how multivalent proteins, in particular, dimers, tetramers, and linear multidentate proteins, assemble with QDs. It also manifests our capability of harnessing structural and conformational information about proteins to design multivalent protein ligands for QD surface functionalization.

Single-crystalline, ultrathin ZnGa(2)O(4) nanosheet scaffolds to promote photocatalytic activity in CO(2) reduction into methane

Uniform hierarchical microspheres scaffolded from ultrathin ZnGa2O4 nanosheets with over 99% exposed facets were synthesized using an easy solvothermal route with ethylenediamine (en)/H2O binary solvents. Substitution of different chain length amines for en results in no formation of the nanosheet structures, indicating that the molecular structure of En is indispensable for the generation of two-dimensional structures. Inheriting both a high surface area of nanosheets and a high crystallinity of bulky materials allows the unique 3D hierarchical nanostructures to possess great CO2 photocatalytic performance. The normalized time-resolved traces of photo-induced absorption recorded from the nanosheet and meso-ZnGa2O4 indicate that the photo-excited carriers can survive longer on the nanosheet, which also contributes to the high photocatalytic activity of the ZnGa2O4 nanosheets.

A class of high performance metal-free oxygen reduction electrocatalysts based on cheap carbon blacks

For the goal of practical industrial development of fuel cells, cheap, sustainable and high performance electrocatalysts for oxygen reduction reactions (ORR) which rival those based on platinum (Pt) and other rare materials are highly desirable. In this work, we report a class of cheap and high-performance metal-free oxygen reduction electrocatalysts obtained by co-doping carbon blacks with nitrogen and fluorine (CB-NF).The CB-NF electrocatalysts are highly active and exhibit long-term operation stability and tolerance to poisons during oxygen reduction process in alkaline medium. The alkaline direct methanol fuel cell with the best CB-NF as cathode (3 mg/cm²) outperforms the one with commercial platinum-based cathode (3 mg _Pt/cm²). To the best of our knowledge, these are among the most efficient non-Pt based electrocatalysts. Since carbon blacks are 10,000 times cheaper than Pt, these CB-NF electrocatalysts possess the best price/performance ratio for ORR, and are the most promising alternatives to Pt-based ones to date.

Insight into Enhanced Cycling Performance of Li-O2 Batteries Based on Binary CoSe2/CoO Nanocomposite Electrodes

In this study, binary core-shell CoSe2/CoO nanocomposites are synthesized as cathodic electrodes for the Li-O2 cell, which exhibits enhanced cycle performance. From theoretical calculations, aberration-corrected scanning transmission electron microscopy observation, and gas chromatography mass spectrum verification, we propose that an enhanced cycle performance can be attributed to the improvement of the compatibility of the cathode/Li2O2 interface, which results from preferable interaction between Li2O2 intermediates and the CoO "shell" and then reduction of interfacial Li2CO3 formation on the carbon surface. Furthermore, our findings demonstrate that the CoSe2 "core" may impact the electronic structure of surface metal ions, generating a superior cycling performance than that of pristine CoO materials. These results will offer some critical insights into the mechanistic process of Li-O2 batteries.

Tailor-made charge-conversional nanocomposite for pH-responsive drug delivery and cell imaging

Imaging labels, therapeutic drugs, as well as many other agents can all be integrated into one nanoplatform to allow for molecular imaging and therapy. With this in mind, herein we report the first example of a tailor-made charge-conversional nanocomposite composed of mesoporous γ-AlO(OH) and upconversion nanoparticles (UCNPs) via a simple and versatile method, and the obtained nanocomposite could be performed as a drug delivery carrier and applied for cell imaging. The nanocomposite (UCNPs-Al) was found to be able to efficiently transport DOX, a typical chemotherapeutic anticancer drug, into the cancer cell and release DOX from UCNPs-Al triggering by the mildly acidic environment. In vitro cell cytotoxicity assay verified that DOX-loaded nanocomposites (UCNPs-Al-DOX) exhibited greater cytotoxicity with respect to free DOX at the same concentrations, because of the increase in cell uptake of anti-cancer drug delivery vehicles mediated by the charge-conversional property. Moreover, the UCL emission from UCNPs and the red fluorescence of DOX allow the nanocomposite to track and monitor the drug delivery system simultaneously. These findings have opened up new insights into designing and producing the highly versatile multifunctional nanoparticles for simultaneous imaging and therapeutic applications.

Measurement and analysis of adhesion property of lithium-ion battery electrodes with SAICAS

The adhesion strength of lithium-ion battery (LIB) electrodes consisting of active material, a nanosized electric conductor, and a polymeric binder is measured with a new analysis tool, called the Surface and Interfacial Cutting Analysis System (SAICAS). Compared to the conventional peel test with the same electrode, SAICAS gives higher adhesion strength owing to its elaborate cutting-based measurement system. In addition, the effects on the adhesion property of the polymeric binder type and content, electrode density, and measuring point are also investigated to determine whether SAICAS provides reliable results. The findings confirm SAICAS as an effective and promising tool to measure and analyze the adhesion properties of LIB electrodes.

Facile synthesis of single-crystalline hollow α-Fe2O3 nanospheres with gas sensing properties

High-quality single-crystalline hollow α-Fe₂O₃ nanospheres were prepared, using ZnS–CHA nanohybrid as additive with gas sensing property.

Hypervalent iodine-catalyzed oxidative amidation of methylarenes

Hypervalent iodine-catalyzed oxidative amidation of methylarenes to the corresponding amides by using an oxidant (tert-butyl hydroperoxide, 70% aqueous solution) is discussed.

Two 3D metal–organic frameworks of Cd(ii): modulation of structures and porous properties based on linker functionalities

Two Cd(ii) based 3D frameworks exhibit interesting structural features and adsorption properties based on the linker functionality modulation.

Controllable synthesis of hierarchical mesoporous/microporous nitrogen-rich polymer networks for CO2 and Cr(vi) ion adsorption

A facile and scalable one-pot approach has been developed for the preparation of hierarchical meso- and microporous nitrogen-rich polymer networks by sol–gel polymerization of melamine, resorcinol and terephthaldehyde.

Heterogeneous electron transfer at nanoscopic electrodes: importance of electronic structures and electric double layers

Recent insights into the nanoscopic electrode size and structure effects on heterogeneous ET kinetics are presented.

Facile synthesis of 3D Pd–P nanoparticle networks with enhanced electrocatalytic performance towards formic acid electrooxidation

3D Pd–P nanoparticle networks (NNs) have been successfully synthesized using a facile one-step soft-template-assisted method. The as-prepared Pd–P NNs exhibit markedly improved activity and stability towards formic acid electrooxidation over Pd NNs, commercial Pd/C and Pd–P nanoparticle aggregates (NAs).

Enhancing the capacitive performance of a textile-based CNT supercapacitor

A metal layer, used as a current collector layer for a textile-based supercapacitor (SC), was prepared on polyethylene terephthalate (PET) fabrics using wet chemical methods.

Di-, tri- and tetranuclear molecular vanadium phosphonates: a chloride encapsulated tetranuclear bowl

Synthesis and characterization of three dinuclear, two dinuclear and one tetranuclear vanadium phosphonates is being reported. These include a chloride encapsulated tetranuclear bowl-shaped complex.

Self-stabilized Pt–Rh bimetallic nanoclusters as durable electrocatalysts for dioxygen reduction in PEM fuel cells

Self-stabilized Pt–Rh nanoclusters (NCs) were prepared by formic acid reduction and used as the durable electrocatalyst for ORR.

Cellular nanotechnology: making biological interfaces smarter

Recently, there has been an outburst of research on engineered cell-material interfaces driven by nanotechnology and its tools and techniques. This tutorial review begins by providing a brief introduction to nanostructured materials, followed by an overview of the wealth of nanoscale fabrication and analysis tools available for their development. This background serves as the basis for a discussion of early breakthroughs and recent key developments in the endeavour to develop nanostructured materials as smart interfaces for fundamental cellular studies, tissue engineering and regenerative medicine. The review covers three major aspects of nanostructured interfaces - nanotopographical control, dynamic behaviour and intracellular manipulation and sensing - where efforts are continuously being made to further understand cell function and provide new ways to control cell behaviour. A critical reflection of the current status and future challenges are discussed as a conclusion to the review.

Controlled assembly of inorganic-organic frameworks based on [SeMo6O21]4- polyanion

The chemical system based on [SeMo6O21](4-) polyanion and carboxylate ligand has been investigated. According to the inherent nature of organic groups, a series of selenomolybdates with three architectures have been isolated through rational and deliberate synthetic routes by stereospecific addition of different carboxylic acids. Such an approach is potentially interesting for {SeMo6} cluster, which exhibits a high surface nucleophilicity and is capable of being functionalized by covalently bound carboxylic acids. Investigation of the assemblies reveals that carboxylic acids have good flexibility and conformational freedom, representing the powerful chemical tools to control the polyanion assembly processes.