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Showing papers in "Angewandte Chemie in 2014"


Journal ArticleDOI
TL;DR: Recent research advances in the rational design and efficient synthesis of MTMOs with controlled shapes, sizes, compositions, and micro-/nanostructures are summarized, along with their applications as electrode materials for lithium-ion batteries and electrochemical capacitors, and efficient electrocatalysts for the oxygen reduction reaction in metal-air batteries and fuel cells.
Abstract: A promising family of mixed transition-metal oxides (MTMOs) (designated as Ax B3-x O4 ; A, B=Co, Ni, Zn, Mn, Fe, etc.) with stoichiometric or even non-stoichiometric compositions, typically in a spinel structure, has recently attracted increasing research interest worldwide. Benefiting from their remarkable electrochemical properties, these MTMOs will play significant roles for low-cost and environmentally friendly energy storage/conversion technologies. In this Review, we summarize recent research advances in the rational design and efficient synthesis of MTMOs with controlled shapes, sizes, compositions, and micro-/nanostructures, along with their applications as electrode materials for lithium-ion batteries and electrochemical capacitors, and efficient electrocatalysts for the oxygen reduction reaction in metal-air batteries and fuel cells. Some future trends and prospects to further develop advanced MTMOs for next-generation electrochemical energy storage/conversion systems are also presented.

1,939 citations


Journal ArticleDOI
TL;DR: Chemical applications of SERS cover a broad range of topics such as catalysis and spectroelectrochemistry, single-molecule detection, and (bio)analytical chemistry.
Abstract: Surface-enhanced Raman scattering (SERS) has become a mature vibrational spectroscopic technique during the last decades and the number of applications in the chemical, material, and in particular life sciences is rapidly increasing. This Review explains the basic theory of SERS in a brief tutorial and-based on original results from recent research-summarizes fundamental aspects necessary for understanding SERS and provides examples for the preparation of plasmonic nanostructures for SERS. Chemical applications of SERS are the centerpiece of this Review. They cover a broad range of topics such as catalysis and spectroelectrochemistry, single-molecule detection, and (bio)analytical chemistry.

1,817 citations


Journal ArticleDOI
TL;DR: Two-dimensional hybrid perovskites are used as absorbers in solar cells and the 3D perovskite (MA)[PbI3] (2) has recently been identified as a promising absorber for solar cells, however, its instability to moisture requires anhydrous processing and operating conditions.
Abstract: Two-dimensional hybrid perovskites are used as absorbers in solar cells. Our first-generation devices containing (PEA)2(MA)2[Pb3I10] (1; PEA=C6H5(CH2)2NH3+, MA=CH3NH3+) show an open-circuit voltage of 1.18 V and a power conversion efficiency of 4.73 %. The layered structure allows for high-quality films to be deposited through spin coating and high-temperature annealing is not required for device fabrication. The 3D perovskite (MA)[PbI3] (2) has recently been identified as a promising absorber for solar cells. However, its instability to moisture requires anhydrous processing and operating conditions. Films of 1 are more moisture resistant than films of 2 and devices containing 1 can be fabricated under ambient humidity levels. The larger bandgap of the 2D structure is also suitable as the higher bandgap absorber in a dual-absorber tandem device. Compared to 2, the layered perovskite structure may offer greater tunability at the molecular level for material optimization.

1,725 citations


Journal ArticleDOI
TL;DR: It is anticipated that precisely engineered nanoparticles will emerge as the next-generation platform for cancer therapy and many other biomedical applications.
Abstract: In medicine, nanotechnology has sparked a rapidly growing interest as it promises to solve a number of issues associated with conventional therapeutic agents, including their poor water solubility (at least, for most anticancer drugs), lack of targeting capability, nonspecific distribution, systemic toxicity, and low therapeutic index. Over the past several decades, remarkable progress has been made in the development and application of engineered nanoparticles to treat cancer more effectively. For example, therapeutic agents have been integrated with nanoparticles engineered with optimal sizes, shapes, and surface properties to increase their solubility, prolong their circulation half-life, improve their biodistribution, and reduce their immunogenicity. Nanoparticles and their payloads have also been favorably delivered into tumors by taking advantage of the pathophysiological conditions, such as the enhanced permeability and retention effect, and the spatial variations in the pH value. Additionally, targeting ligands (e.g., small organic molecules, peptides, antibodies, and nucleic acids) have been added to the surface of nanoparticles to specifically target cancerous cells through selective binding to the receptors overexpressed on their surface. Furthermore, it has been demonstrated that multiple types of therapeutic drugs and/or diagnostic agents (e.g., contrast agents) could be delivered through the same carrier to enable combination therapy with a potential to overcome multidrug resistance, and real-time readout on the treatment efficacy. It is anticipated that precisely engineered nanoparticles will emerge as the next-generation platform for cancer therapy and many other biomedical applications.

1,603 citations


Journal ArticleDOI
TL;DR: It is reported that flat, uniform thin films of this material can be deposited by a one-step, solvent-induced, fast crystallization method involving spin-coating of a DMF solution of CH3NH3PbI3 followed immediately by exposure to chlorobenzene to induce crystallization.
Abstract: Thin-film photovoltaics based on alkylammonium lead iodide perovskite light absorbers have recently emerged as a promising low-cost solar energy harvesting technology. To date, the perovskite layer in these efficient solar cells has generally been fabricated by either vapor deposition or a two-step sequential deposition process. We report that flat, uniform thin films of this material can be deposited by a one-step, solvent-induced, fast crystallization method involving spin-coating of a DMF solution of CH3NH3PbI3 followed immediately by exposure to chlorobenzene to induce crystallization. Analysis of the devices and films revealed that the perovskite films consist of large crystalline grains with sizes up to microns. Planar heterojunction solar cells constructed with these solution-processed thin films yielded an average power conversion efficiency of 13.9±0.7% and a steady state efficiency of 13% under standard AM 1.5 conditions.

1,554 citations


Journal ArticleDOI
TL;DR: This Review highlights the recent progress in the field of cross-dehydrogenative C sp 3C formations and provides a comprehensive overview on existing procedures and employed methodologies.
Abstract: Over the last decade, substantial research has led to the introduction of an impressive number of efficient procedures which allow the selective construction of CC bonds by directly connecting two different CH bonds under oxidative conditions. Common to these methodologies is the generation of the reactive intermediates in situ by activation of both CH bonds. This strategy was introduced by the group of Li as cross-dehydrogenative coupling (CDC) and discloses waste-minimized synthetic alternatives to classic coupling procedures which rely on the use of prefunctionalized starting materials. This Review highlights the recent progress in the field of cross-dehydrogenative C sp 3C formations and provides a comprehensive overview on existing procedures and employed methodologies.

1,528 citations


Journal ArticleDOI
TL;DR: A promising strategy to develop such an understanding is the investigation of the impact of material properties on reaction activity/selectivity and on catalyst stability under the conditions of operation, as well as the application of complementary in situ techniques for the Investigation of catalyst structure and composition.
Abstract: Electrochemistry will play a vital role in creating sustainable energy solutions in the future, particularly for the conversion and storage of electrical into chemical energy in electrolysis cells, and the reverse conversion and utilization of the stored energy in galvanic cells. The common challenge in both processes is the development of-preferably abundant-nanostructured materials that can catalyze the electrochemical reactions of interest with a high rate over a sufficiently long period of time. An overall understanding of the related processes and mechanisms occurring under the operation conditions is a necessity for the rational design of materials that meet these requirements. A promising strategy to develop such an understanding is the investigation of the impact of material properties on reaction activity/selectivity and on catalyst stability under the conditions of operation, as well as the application of complementary in situ techniques for the investigation of catalyst structure and composition.

1,153 citations


Journal ArticleDOI
TL;DR: This work shows that the goal of extending the optical-absorption onset of perovskite-based photovoltaics further into the red to enhance solar-light harvesting can be reached by using a mixture of formamidinium and methylammonium cations, which leads to an enhanced short-circuit current and thus superior devices to those based on only CH3 NH3 (+).
Abstract: Hybrid organic–inorganic lead halide perovskite APbX3 pigments, such as methylammonium lead iodide, have recently emerged as excellent light harvesters in solid-state mesoscopic solar cells. An important target for the further improvement of the performance of perovskite-based photovoltaics is to extend their optical-absorption onset further into the red to enhance solar-light harvesting. Herein, we show that this goal can be reached by using a mixture of formamidinium (HN=CHNH3+, FA) and methylammonium (CH3NH3+, MA) cations in the A position of the APbI3 perovskite structure. This combination leads to an enhanced short-circuit current and thus superior devices to those based on only CH3NH3+. This concept has not been applied previously in perovskite-based solar cells. It shows great potential as a versatile tool to tune the structural, electrical, and optoelectronic properties of the light-harvesting materials.

1,152 citations


Journal ArticleDOI
TL;DR: The activity was essentially unchanged after 400 cyclic voltammetric sweeps, suggesting long-term viability under operating conditions, and CoP is amongst the most active, acid-stable, earth-abundant HER electrocatalysts reported to date.
Abstract: Nanoparticles of cobalt phosphide, CoP, have been prepared and evaluated as electrocatalysts for the hydrogen evolution reaction (HER) under strongly acidic conditions (0.50 M H_2SO_4, pH 0.3). Uniform, multi-faceted CoP nanoparticles were synthesized by reacting Co nanoparticles with trioctylphosphine. Electrodes comprised of CoP nanoparticles on a Ti support (2 mg cm^(−2) mass loading) produced a cathodic current density of 20 mA cm^(−2) at an overpotential of −85 mV. The CoP/Ti electrodes were stable over 24 h of sustained hydrogen production in 0.50 M H_2SO_4. The activity was essentially unchanged after 400 cyclic voltammetric sweeps, suggesting long-term viability under operating conditions. CoP is therefore amongst the most active, acid-stable, earth-abundant HER electrocatalysts reported to date.

1,118 citations


Journal ArticleDOI
TL;DR: A nanohybrid that consists of carbon nanotubes decorated with CoP nanocrystals (CoP/CNT) was prepared by the low-temperature phosphidation of a Co3O4/C NT precursor and only requires overpotentials of 70 and 122 mV to attain current densities of 2 and 10 mA cm(-2), respectively.
Abstract: The development of effective and inexpensive hydrogen evolution reaction (HER) electrocatalysts for future renewable energy systems is highly desired. The strongly acidic conditions in proton exchange membranes create a need for acid-stable HER catalysts. A nanohybrid that consists of carbon nanotubes decorated with CoP nanocrystals (CoP/CNT) was prepared by the low-temperature phosphidation of a Co3O4/CNT precursor. As a novel non-noble-metal HER catalyst operating in acidic electrolytes, the nanohybrid exhibits an onset overpotential of as low as 40 mV, a Tafel slope of 54 mV dec−1, an exchange current density of 0.13 mA cm−2, and a Faradaic efficiency of nearly 100 %. This catalyst maintains its catalytic activity for at least 18 hours and only requires overpotentials of 70 and 122 mV to attain current densities of 2 and 10 mA cm−2, respectively.

1,007 citations


Journal ArticleDOI
TL;DR: An effective strategy for synthesizing extremely active graphitic carbon nitride (g-C3N4) from a low-cost precursor, urea, is reported, and it was found that as the degree of polymerization increases and the proton concentration decreases, the hydrogen-evolution rate is significantly enhanced.
Abstract: The major challenge of photocatalytic water splitting, the prototypical reaction for the direct production of hydrogen by using solar energy, is to develop low-cost yet highly efficient and stable semiconductor photocatalysts. Herein, an effective strategy for synthesizing extremely active graphitic carbon nitride (g-C3N4) from a low-cost precursor, urea, is reported. The g-C3N4 exhibits an extraordinary hydrogen-evolution rate (ca. 20 000 μmol h−1 g−1 under full arc), which leads to a high turnover number (TON) of over 641 after 6 h. The reaction proceeds for more than 30 h without activity loss and results in an internal quantum yield of 26.5 % under visible light, which is nearly an order of magnitude higher than that observed for any other existing g-C3N4 photocatalysts. Furthermore, it was found by experimental analysis and DFT calculations that as the degree of polymerization increases and the proton concentration decreases, the hydrogen-evolution rate is significantly enhanced.

Journal ArticleDOI
TL;DR: The origins of the CCDC are traced, the growth of the CSD and its extensive associated software system are described, and its impact and value are summarized as a basis for research in structural chemistry, materials science and the life sciences, including drug discovery and drug development.
Abstract: The Cambridge Crystallographic Data Centre (CCDC) was established in 1965 to record numerical, chemical and bibliographic data relating to published organic and metal–organic crystal structures. The Cambridge Structural Database (CSD) now stores data for nearly 700 000 structures and is a comprehensive and fully retrospective historical archive of small-molecule crystallography. Nearly 40 000 new structures are added each year. As X-ray crystallography celebrates its centenary as a subject, and the CCDC approaches its own 50th year, this article traces the origins of the CCDC as a publicly funded organization and its onward development into a self-financing charitable institution. Principally, however, we describe the growth of the CSD and its extensive associated software system, and summarize its impact and value as a basis for research in structural chemistry, materials science and the life sciences, including drug discovery and drug development. Finally, the article considers the CCDC’s funding model in relation to open access and open data paradigms.

Journal ArticleDOI
TL;DR: The synthesis of cobalt-embedded nitrogen-rich carbon nanotubes (NRCNTs) that can efficiently electrocatalyze the hydrogen evolution reaction (HER) with activities close to that of Pt and function well under acidic, neutral or basic media alike, allowing them to be coupled with the best available oxygen-evolving catalysts.
Abstract: Despite being technically possible, splitting water to generate hydrogen is still practically unfeasible due mainly to the lack of sustainable and efficient catalysts for the half reactions involved. Herein we report the synthesis of cobalt-embedded nitrogen-rich carbon nanotubes (NRCNTs) that 1) can efficiently electrocatalyze the hydrogen evolution reaction (HER) with activities close to that of Pt and 2) function well under acidic, neutral or basic media alike, allowing them to be coupled with the best available oxygen-evolving catalysts-which also play crucial roles in the overall water-splitting reaction. The materials are synthesized by a simple, easily scalable synthetic route involving thermal treatment of Co(2+) -embedded graphitic carbon nitride derived from inexpensive starting materials (dicyandiamide and CoCl2 ). The materials' efficient catalytic activity is mainly attributed to their nitrogen dopants and concomitant structural defects.

Journal ArticleDOI
TL;DR: The extraordinarily high activity and stability of this catalyst open up avenues to replace platinum in technologies relevant to renewable energies, such as proton exchange membrane (PEM) electrolyzers and solar photoelectrochemical (PEC) water-splitting cells.
Abstract: Introducing sulfur into the surface of molybdenum phosphide (MoP) produces a molybdenum phosphosulfide (MoP|S) catalyst with superb activity and stability for the hydrogen evolution reaction (HER) in acidic environments. The MoP|S catalyst reported herein exhibits one of the highest HER activities of any non-noble-metal electrocatalyst investigated in strong acid, while remaining perfectly stable in accelerated durability testing. Whereas mixed-metal alloy catalysts are well-known, MoP|S represents a more uncommon mixed-anion catalyst where synergistic effects between sulfur and phosphorus produce a high-surface-area electrode that is more active than those based on either the pure sulfide or the pure phosphide. The extraordinarily high activity and stability of this catalyst open up avenues to replace platinum in technologies relevant to renewable energies, such as proton exchange membrane (PEM) electrolyzers and solar photoelectrochemical (PEC) water-splitting cells.


Journal ArticleDOI
TL;DR: Perovskites are of great interest in photovoltaic devices due to their panchromatic light absorption and ambipolar behavior and it will not be unrealistic to speculate that one day perovskite-based solar cells can match the capability and capacity of existing technologies.
Abstract: It is not often that the scientific community is blessed with a material, which brings enormous hopes and receives special attention. When it does, it expands at a rapid pace and its every dimension creates curiosity. One such material is perovskite, which has triggered the development of new device architectures in energy conversion. Perovskites are of great interest in photovoltaic devices due to their panchromatic light absorption and ambipolar behavior. Power conversion efficiencies have been doubled in less than a year and over 15% is being now measured in labs. Every digit increment in efficiency is being celebrated widely in the scientific community and is being discussed in industry. Here we provide a summary on the use of perovskite for inexpensive solar cells fabrication. It will not be unrealistic to speculate that one day perovskite-based solar cells can match the capability and capacity of existing technologies.

Journal ArticleDOI
TL;DR: The restriction to ultrasmall reaction domains allows for an almost diffusion-less and nucleation-free "conversion" of MoS2 nanodots, thereby resulting in a high capacity and a remarkable cycling performance.
Abstract: The preparation and electrochemical storage behavior of MoS2 nanodots--more precisely single-layered ultrasmall nanoplates--embedded in carbon nanowires has been studied. The preparation is achieved by an electrospinning process that can be easily scaled up. The rate performance and cycling stability of both lithium and sodium storage were found to be outstanding. The storage behavior is, moreover, highly exciting from a fundamental point of view, as the differences between the usual storage modes--insertion, conversion, interfacial storage--are beneficially blurred. The restriction to ultrasmall reaction domains allows for an almost diffusion-less and nucleation-free "conversion", thereby resulting in a high capacity and a remarkable cycling performance.

Journal ArticleDOI
TL;DR: An FeP nanowire array was developed on Ti plate (FeP NA/Ti) from its β-FeOOH NA/ Ti precursor through a low-temperature phosphidation reaction, showing exceptionally high catalytic activity and good durability when applied as self-supported 3D hydrogen evolution cathode.
Abstract: Iron is the cheapest and one of the most abundant transition metals. Natural (FeFe)-hydrogenases exhibit remarkably high activity in hydrogen evolution, but they suffer from high oxygen sensitivity and difficulty in scale-up. Herein, an FeP nanowire array was developed on Ti plate (FeP NA/Ti) from its b-FeOOH NA/Ti precursor through a low- temperature phosphidation reaction. When applied as self- supported 3D hydrogen evolution cathode, the FeP NA/Ti electrode shows exceptionally high catalytic activity and good durability, and it only requires overpotentials of 55 and 127 mV to afford current densities of 10 and 100 mA cm 2 , respectively. The excellent electrocatalytic performance is promising for applications as non-noble-metal HER catalyst with a high performance-price ratio in electrochemical water splitting for large-scale hydrogen fuel production. Hydrogen as a promising clean chemical fuel is an ideal energy carrier for sustainable energy applications. (1) Electro- chemical reduction of water for hydrogen production is an important component of several emerging clean-energy technologies, but an efficient electrocatalyst for the hydrogen evolution reaction (HER) is required to afford high current at low overpotential. (2) Although Pt-based catalysts show high catalytic performance, they suffer from high costs and the scarcity of Pt. (3) Water electrolysis based on proton exchange membrane (PEM) technology and many solar water splitting devices operate under strongly acidic conditions, (4) it is thus highly attractive to develop acid-stable HER catalysts made from earth-abundant elements. Catalysts based on Mo, W, and Fe-group elements have received great attention, includ-

Journal ArticleDOI
TL;DR: New 2D sandwich-like zeolitic imidazolate framework (ZIF) derived graphene-based nitrogen-doped porous carbon sheets (GNPCSs) obtained by in situ growing ZIF on graphene oxide (GO) show comparable onset potential, higher current density, and especially an excellent tolerance to methanol and superior durability in the ORR.
Abstract: Nitrogen-doped carbon (NC) materials have been proposed as next-generation oxygen reduction reaction (ORR) catalysts to significantly improve scalability and reduce costs, but these alternatives usually exhibit low activity and/or gradual deactivation during use. Here, we develop new 2D sandwich-like zeolitic imidazolate framework (ZIF) derived graphene-based nitrogen-doped porous carbon sheets (GNPCSs) obtained by in situ growing ZIF on graphene oxide (GO). Compared to commercial Pt/C catalyst, the GNPCSs show comparable onset potential, higher current density, and especially an excellent tolerance to methanol and superior durability in the ORR. Those properties might be attributed to a synergistic effect between NC and graphene with regard to structure and composition. Furthermore, higher open-circuit voltage and power density are obtained in direct methanol fuel cells.

Journal ArticleDOI
TL;DR: This is the topotactic fabrication of self-supported Cu3 P nanowire arrays on commercial porous copper foam from its Cu(OH)2 NW/CF precursor by a low-temperature phosphidation reaction.
Abstract: Searching for inexpensive hydrogen evolution reaction (HER) electrocatalysts with high activity has attracted considerable research interest in the past years. Reported herein is the topotactic fabrication of self-supported Cu3P nanowire arrays on commercial porous copper foam (Cu3P NW/CF) from its Cu(OH)(2) NW/CF precursor by a low-temperature phosphidation reaction. Remarkably, as an integrated three-dimensional hydrogen-evolving cathode operating in acidic electrolytes, Cu3P NW/CF maintains its activity for at least 25 hours and exhibits an onset overpotential of 62 mV, a Tafel slope of 67 mVdec(-1), and a Faradaic efficiency close to 100%. Catalytic current density can approach 10 mAcm(-2) at an overpotential of 143 mV.

Journal ArticleDOI
TL;DR: This Review highlights the appropriate tools for successfully employing donor-acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.
Abstract: The effective use of ring strain has been applied to considerable advantage for the construction of complex systems. The focus here is directed towards cyclopropanes as building blocks for organic synthesis. Although thermodynamics should take the side of synthetic chemists, only a specific substitution pattern at the cyclopropane ring allows for particularly mild, efficient, and selective transformations. The required decrease in the activation barrier is achieved by the combined effects of vicinal electron-donating and electron-accepting moieties. This Review highlights the appropriate tools for successfully employing donor–acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.

Journal ArticleDOI
TL;DR: The application of anisotropic AuNPs has rapidly spread to optical, biomedical, and catalytic areas, and a summary of the synthetic modes, variety of shapes, applications, and toxicity issues of this fast-growing class of nanomaterials is given.
Abstract: Anisotropic gold nanoparticles (AuNPs) have attracted the interest of scientists for over a century, but research in this field has considerably accelerated since 2000 with the synthesis of numerous 1D, 2D, and 3D shapes as well as hollow AuNP structures. The anisotropy of these nonspherical, hollow, and nanoshell AuNP structures is the source of the plasmon absorption in the visible region as well as in the near-infrared (NIR) region. This NIR absorption is especially sensitive to the AuNP shape and medium and can be shifted towards the part of the NIR region in which living tissue shows minimum absorption. This has led to crucial applications in medical diagnostics and therapy ("theranostics"), especially with Au nanoshells, nanorods, hollow nanospheres, and nanocubes. In addition, Au nanowires (AuNWs) can be synthesized with longitudinal dimensions of several tens of micrometers and can serve as plasmon waveguides for sophisticated optical devices. The application of anisotropic AuNPs has rapidly spread to optical, biomedical, and catalytic areas. In this Review, a brief historical survey is given, followed by a summary of the synthetic modes, variety of shapes, applications, and toxicity issues of this fast-growing class of nanomaterials.

Journal ArticleDOI
TL;DR: A novel type of catalysts prepared by high-pressure pyrolysis is reported, featured by hollow spherical morphologies consisting of uniform iron carbide (Fe3 C) nanoparticles encased by graphitic layers, with little surface nitrogen or metallic functionalities.
Abstract: Nonprecious metal catalysts for the oxygen reduction reaction are the ultimate materials and the foremost subject for low-temperature fuel cells. A novel type of catalysts prepared by high-pressure pyrolysis is reported. The catalyst is featured by hollow spherical morphologies consisting of uniform iron carbide (Fe3 C) nanoparticles encased by graphitic layers, with little surface nitrogen or metallic functionalities. In acidic media the outer graphitic layers stabilize the carbide nanoparticles without depriving them of their catalytic activity towards the oxygen reduction reaction (ORR). As a result the catalyst is highly active and stable in both acid and alkaline electrolytes. The synthetic approach, the carbide-based catalyst, the structure of the catalysts, and the proposed mechanism open new avenues for the development of ORR catalysts.

Journal ArticleDOI
TL;DR: A new class of highly efficient oxygen evolution catalysts has been synthesized through the self-assembly of graphitic carbon nitride nanosheets and carbon nanotubes, driven by π-π stacking and electrostatic interactions, and exhibit higher catalytic oxygen evolution activity and stronger durability than Ir-based noble-metal catalysts.
Abstract: A new class of highly efficient oxygen evolution catalysts has been synthesized through the self-assembly of graphitic carbon nitride nanosheets and carbon nanotubes, driven by π-π stacking and electrostatic interactions. Remarkably, the catalysts exhibit higher catalytic oxygen evolution activity and stronger durability than Ir-based noble-metal catalysts and display the best performance among the reported nonmetal catalysts. This good result is attributed to the high nitrogen content and the efficient mass and charge transfer in the porous three-dimensional nanostructure.

Journal ArticleDOI
TL;DR: How the lessons learned from the first-generation ADCs have led to improvements in every aspect of this technology, i.e., the antibody, the cytotoxic compound, and the linker connecting them, leading to the current successes are described.
Abstract: Traditional cancer chemotherapy is often accompanied by systemic toxicity to the patient. Monoclonal antibodies against antigens on cancer cells offer an alternative tumor-selective treatment approach. However, most monoclonal antibodies are not sufficiently potent to be therapeutically active on their own. Antibody-drug conjugates (ADCs) use antibodies to deliver a potent cytotoxic compound selectively to tumor cells, thus improving the therapeutic index of chemotherapeutic agents. The recent approval of two ADCs, brentuximab vedotin and ado-trastuzumab emtansine, for cancer treatment has spurred tremendous research interest in this field. This Review touches upon the early efforts in the field, and describes how the lessons learned from the first-generation ADCs have led to improvements in every aspect of this technology, i.e., the antibody, the cytotoxic compound, and the linker connecting them, leading to the current successes. The design of ADCs currently in clinical development, and results from mechanistic studies and preclinical and clinical evaluation are discussed. Emerging technologies that seek to further advance this exciting area of research are also discussed.

Journal ArticleDOI
TL;DR: A novel strategy is used to synthesize a non-noble-metal-based electrocatalyst of the OER by finely combining layered FeNi double hydroxide that is catalytically active and electric conducting graphene sheets, taking advantage of the electrostatic attraction between the two positively charged nanosheets.
Abstract: Cost-effective electrocatalysts for the oxygen evolu- tion reaction (OER) are critical to energy conversion and storage processes. A novel strategy is used to synthesize a non- noble-metal-based electrocatalyst of the OER by finely com- bining layered FeNi double hydroxide that is catalytically active and electric conducting graphene sheets, taking advant- age of the electrostatic attraction between the two positively charged nanosheets. The synergy between the catalytic activity of the double hydroxide and the enhanced electron transport arising from the graphene resulted in superior electrocatalytic properties of the FeNi-GO hybrids for the OER with over- potentials as low as 0.21 V, which was further reduced to 0.195 V after the reduction treatment. Moreover, the turnover frequency at the overpotential of 0.3 V has reached 1 s 1 , which is much higher than those previously reported for non-noble- metal-based electrocatalysts. The growing demand for energy and the increasing concerns about environment pollution from fossil fuels are stimulating intense research interest in energy conversion and storage from alternative sustainable energy sources. As one of the most important process to produce and store renewable energy in chemical form, the oxygen evolution reaction (OER) has led to many studies in recent years. However, the kinetics of OER is sluggish. Therefore, an effective electro- catalyst is needed to accelerate the reaction and reduce the large overpotential and thus improve the energy conversion efficiency. Metal oxides are the most active and durable electrocatalysts for OER, among which IrO2 and RuO2 are thought to be best OER catalysts in both acidic and alkaline solutions. (1) However, the high cost and element scarcity greatly hindered the widespread use of these noble-metal oxide catalysts. Therefore, it is desirable to develop efficient alternative catalysts based on inexpensive and earth-abun- dant elements without compromising good catalytic activity and durability for OER. Recently, extensive efforts have been made to use perovskites (2) and first-row transition-metal- based materials (3) as low-cost catalysts or electrode materials

Journal ArticleDOI
TL;DR: In this article, four phases of molybdenum carbide were synthesized and investigated for their electrocatalytic activity and stability for hydrogen evolution reaction in acidic solution.
Abstract: Molybdenum carbide has been proposed as a possible alternative to platinum for catalyzing the hydrogen evolution reaction (HER). Previous studies were limited to only one phase, β-Mo2C with an Fe2N structure. Here, four phases of Mo-C were synthesized and investigated for their electrocatalytic activity and stability for HER in acidic solution. All four phases were synthesized from a unique amine-metal oxide composite material including γ-MoC with a WC type structure which was stabilized for the first time as a phase pure nanomaterial. X-ray photoelectron spectroscopy (XPS) and valence band studies were also used for the first time on γ-MoC. γ-MoC exhibits the second highest HER activity among all four phases of molybdenum carbide, and is exceedingly stable in acidic solution.

Journal ArticleDOI
TL;DR: Highlights of the electrode reaction are its high energy efficiency, the small irreversible loss during the first cycle, and a superior cycle life with capacities close to 100 mAh g(-1) for 1000 cycles and coulomb efficiencies >99.87%.
Abstract: Although being the standard anode material in lithium-ion batteries (LIBs), graphite so far is considered to fail application in sodium-ion batteries (NIBs) because the Na-C system lacks suitable binary intercalation compounds. Here we show that this limitation can be circumvented by using co-intercalation phenomena in a diglyme-based electrolyte. The resulting compound is a stage-I ternary intercalation compound with an estimated stoichiometry of Na(diglyme)2C20. Highlights of the electrode reaction are its high energy efficiency, the small irreversible loss during the first cycle, and a superior cycle life with capacities close to 100 mAh g−1 for 1000 cycles and coulomb efficiencies >99.87 %. A one-to-one comparison with the analogue lithium-based cell shows that the sodium-based system performs better and also withstands higher currents.

Journal ArticleDOI
Zhe Hu1, Wang Lixiu1, Kai Zhang1, Jianbin Wang1, Fangyi Cheng1, Zhanliang Tao1, Jun Chen1 
TL;DR: MoS2 nanoflowers with expanded interlayer spacing of the (002) plane were synthesized and used as high-performance anode in Na-ion batteries and hold promise for rechargeable Na(+) batteries.
Abstract: MoS2 nanoflowers with expanded interlayer spacing of the (002) plane were synthesized and used as high-performance anode in Na-ion batteries. By controlling the cut-off voltage to the range of 0.4–3 V, an intercalation mechanism rather than a conversion reaction is taking place. The MoS2 nanoflower electrode shows high discharge capacities of 350 mAh g−1 at 0.05 A g−1, 300 mAh g−1 at 1 A g−1, and 195 mAh g−1 at 10 A g−1. An initial capacity increase with cycling is caused by peeling off MoS2 layers, which produces more active sites for Na+ storage. The stripping of MoS2 layers occurring in charge/discharge cycling contributes to the enhanced kinetics and low energy barrier for the intercalation of Na+ ions. The electrochemical reaction is mainly controlled by the capacitive process, which facilitates the high-rate capability. Therefore, MoS2 nanoflowers with expanded interlayers hold promise for rechargeable Na-ion batteries.

Journal ArticleDOI
TL;DR: The ability to incorporate multiple metals into functional metal-phenolic network (MPN) capsules demonstrates that a diverse range of functional materials can be generated.
Abstract: Metal-organic coordination materials are of widespread interest because of the coupled benefits of inorganic and organic building blocks. These materials can be assembled into hollow capsules with a range of properties, which include selective permeability, enhanced mechanical/thermal stability, and stimuli-responsiveness. Previous studies have primarily focused on the assembly aspects of metal-coordination capsules; however, the engineering of metal-specific functionality for capsule design has not been explored. A library of functional metal-phenolic network (MPN) capsules prepared from a phenolic ligand (tannic acid) and a range of metals is reported. The properties of the MPN capsules are determined by the coordinated metals, allowing for control over film thickness, disassembly characteristics, and fluorescence behavior. Furthermore, the functional properties of the MPN capsules were tailored for drug delivery, positron emission tomography (PET), magnetic resonance imaging (MRI), and catalysis. The ability to incorporate multiple metals into MPN capsules demonstrates that a diverse range of functional materials can be generated.