Showing papers in "Chemistry of Materials in 2017"
TL;DR: Two-dimensional transition metal carbides, carbonitrides, and nitrides (MXenes) were discovered in 2011 and more than 20 different compositions have been synthesized by the selective etching of MAX phase and other precursors and many more theoretically predicted as mentioned in this paper.
Abstract: Two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides (MXenes) were discovered in 2011. Since the original discovery, more than 20 different compositions have been synthesized by the selective etching of MAX phase and other precursors and many more theoretically predicted. They offer a variety of different properties, making the family promising candidates in a wide range of applications, such as energy storage, electromagnetic interference shielding, water purification, electrocatalysis, and medicine. These solution-processable materials have the potential to be highly scalable, deposited by spin, spray, or dip coating, painted or printed, or fabricated in a variety of ways. Due to this promise, the amount of research on MXenes has been increasing, and methods of synthesis and processing are expanding quickly. The fast evolution of the material can also be noticed in the wide range of synthesis and processing protocols that determine the yield of delamination, as well as the quality...
2,559 citations
TL;DR: A review of the field of hydrogels and aerogels incorporating nanocelluloses can be found in this paper, where over 200 references are summarized in comprehensive tables and a discussion of the challenges and benefits of using CNCs and CNFs as reinforcing agents in conventional plastics is presented.
Abstract: Naturally derived cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are emerging nanomaterials that display high strength, high surface area, and tunable surface chemistry, allowing for controlled interactions with polymers, nanoparticles, small molecules, and biological materials. Industrial production of nanocelluloses is increasing rapidly with several companies already producing on the tons-per-day scale, intensifying the quest for viable products across many sectors. While the hydrophilicity of the nanocellulose interface has posed a challenge to the use of CNCs and CNFs as reinforcing agents in conventional plastics, it is a significant benefit for creating reinforced or structured hydrogel composites (or, when dried, aerogels) exhibiting both mechanical reinforcement and a host of other desirable properties. In this context, this Review describes the quickly growing field of hydrogels and aerogels incorporating nanocelluloses; over 200 references are summarized in comprehensive tables ...
952 citations
TL;DR: In this article, the degradation of delaminated-Ti3C2Tx colloidal solutions was investigated and protocols to improve their stability were proposed. But the degradation was limited to 5, 10, and 15 days.
Abstract: Two-dimensional (2D) transition metal carbides and nitrides (MXenes) have shown outstanding performances in electrochemical energy storage and many other applications. Delamination of MXene flakes in water produces colloidal solutions that are used to manufacture all kinds of products (thin films, coatings, and electrodes, etc.). However, the stability of MXene colloidal solutions, which is of critical importance to their application, remains largely unexplored. Here we report on the degradation of delaminated-Ti3C2Tx colloidal solutions (T represents the surface functionalities) and outline protocols to improve their stability. Ti3C2Tx MXene solutions in open vials degraded by 42%, 85%, and 100% after 5, 10, and 15 days, respectively, leading to the formation of cloudy-white colloidal solutionss containing primarily anatase (TiO2). On the other hand, the solution could be well-preserved when Ti3C2Tx MXene colloidal solutionss were stored in hermetic Ar-filled bottles at 5 °C, because dissolved oxygen, th...
935 citations
TL;DR: In this article, the authors reviewed molecular design strategies of organic-based TADF emitters by classifying them into several categories depending on the material parameters required for the TADFs.
Abstract: Recently, organic thermally activated delayed fluorescence (TADF) emitters have attracted a great deal of attention because they can theoretically realize 100% internal quantum efficiency. Many TADF emitters have been developed since the first demonstration of close to 20% external quantum efficiency in the devices. Recently developed TADF emitters demonstrated close to 37% external quantum efficiency in blue, above 30% external quantum efficiency in green, and close to 18% external quantum efficiency in red devices. Therefore, TADF organic light-emitting diodes could potentially be substituted for high-efficiency phosphorescent organic light-emitting diodes. In this work, we reviewed molecular design strategies of organic-based TADF emitters by classifying them into several categories depending on the material parameters required for the TADF emitters. In addition, we proposed a future development direction of TADF emitters to make them competitive with phosphorescent emitters.
681 citations
TL;DR: The generation and characterization of the most complete collection of metal–organic frameworks (MOFs) maintained and updated, for the first time, by the Cambridge Crystallographic Data Centre (CCDC).
Abstract: We report the generation and characterization of the most complete collection of metal–organic frameworks (MOFs) maintained and updated, for the first time, by the Cambridge Crystallographic Data Centre (CCDC). To set up this subset, we asked the question “what is a MOF?” and implemented a number of “look-for-MOF” criteria embedded within a bespoke Cambridge Structural Database (CSD) Python API workflow to identify and extract information on 69 666 MOF materials. The CSD MOF subset is updated regularly with subsequent MOF additions to the CSD, bringing a unique record for all researchers working in the area of porous materials around the world, whether to perform high-throughput computational screening for materials discovery or to have a global view over the existing structures in a single resource. Using this resource, we then developed and used an array of computational tools to remove residual solvent molecules from the framework pores of all the MOFs identified and went on to analyze geometrical and ...
634 citations
TL;DR: In this article, the authors present the successful implementation of a Li[Ni,Co,Mn]O2 material with high nickel content (LiNi0.8Co0.1Mn 0.1O2, NCM-811) in a bulk-type solid state battery with β-Li3PS4 as a sulfide-based solid electrolyte.
Abstract: All-solid-state lithium ion batteries may become long-term, stable, high-performance energy storage systems for the next generation of electric vehicles and consumer electronics, depending on the compatibility of electrode materials and suitable solid electrolytes. Nickel-rich layered oxides are nowadays the benchmark cathode materials for conventional lithium ion batteries because of their high storage capacity and the resulting high energy density, and their use in solid-state systems is the next necessary step. In this study, we present the successful implementation of a Li[Ni,Co,Mn]O2 material with high nickel content (LiNi0.8Co0.1Mn0.1O2, NCM-811) in a bulk-type solid-state battery with β-Li3PS4 as a sulfide-based solid electrolyte. We investigate the interface behavior at the cathode and demonstrate the important role of the interface between the active materials and the solid electrolyte for the battery performance. A passivating cathode/electrolyte interphase layer forms upon charging and leads to...
586 citations
TL;DR: In this paper, the authors show that two-dimensional titanium carbide (Ti3C2Tx) MXene can be dispersed in many polar organic solvents, but the best dispersions were achieved in N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, propylene carbonate, and ethanol.
Abstract: Two-dimensional titanium carbide (Ti3C2Tx) MXene has attracted a great deal of attention in the research community and has already showed promise in numerous applications, but only its dispersions in aqueous solutions have previously been available. Here we show that Ti3C2Tx can be dispersed in many polar organic solvents, but the best dispersions were achieved in N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, propylene carbonate, and ethanol. The dispersions were examined by measuring the concentration and absorbance spectra of MXene in organic solvents as well as correlating the concentration to solvent physical properties, such as surface tension, boiling point, and polarity index. Hildebrand and Hansen solubility parameters were additionally used to provide an initial understanding of how Ti3C2Tx MXene behaves in organic media and potentially develop quantitative correlations to select solvents and their combinations that can disperse Ti3C2Tx and other MXenes. Using this analysis, ...
575 citations
TL;DR: In this paper, the impact of surface chemistry on the interfacial resistance between the Li7La3Zr2O12 (LLZO) solid-state electrolyte and a metallic Li electrode is revealed.
Abstract: The impact of surface chemistry on the interfacial resistance between the Li7La3Zr2O12 (LLZO) solid-state electrolyte and a metallic Li electrode is revealed. Control of surface chemistry allows the interfacial resistance to be reduced to 2 Ω cm2, lower than that of liquid electrolytes, without the need for interlayer coatings. A mechanistic understanding of the origins of ultra-low resistance is provided by quantitatively evaluating the linkages between interfacial chemistry, Li wettability, and electrochemical phenomena. A combination of Li contact angle measurements, X-ray photoelectron spectroscopy (XPS), first-principles calculations, and impedance spectroscopy demonstrates that the presence of common LLZO surface contaminants, Li2CO3 and LiOH, result in poor wettability by Li and high interfacial resistance. On the basis of this mechanism, a simple procedure for removing these surface layers is demonstrated, which results in a dramatic increase in Li wetting and the elimination of nearly all interfa...
521 citations
TL;DR: In this article, the authors focus on potentially scalable, inexpensive electrode materials and the understanding of their cycle-life-property correlations for nonaqueous potassium-ion batteries, i.e., hard carbon as anode and Prussian white analogues as cathode.
Abstract: The ever-increasing demand for storing renewable energy sources calls for novel battery technologies that are of sustainably low levelized energy cost. Research into battery chemistry has evolved to a stage where a plethora of choices based on earth-abundant elements can be compared during their development. One of the emerging candidates is the nonaqueous potassium-ion battery. K-ion’s unique properties as a charge carrier have aroused intense interest in exploring high-performing cathode and anode materials for this battery. Rapid progress has been made, where leading candidates of electrodes have been proposed, i.e., hard carbon as anode and Prussian white analogues as cathode. In this new battery technology’s infancy, it is our opinion that the focus should be given to potentially scalable, inexpensive electrode materials and the understanding of their cycle-life-property correlations. It may be the ultralong cycle life that differentiates potassium-ion batteries from sodium-ion batteries in the futur...
512 citations
TL;DR: In this paper, a facile metal-organic framework-engaged strategy was presented to synthesize hollow Co3S4@MoS2 heterostructures as efficient bifunctional catalysts for both H2 and O2 generation.
Abstract: Herein, we present a facile metal–organic framework-engaged strategy to synthesize hollow Co3S4@MoS2 heterostructures as efficient bifunctional catalysts for both H2 and O2 generation. The well-known cobalt-based metal–organic zeolitic imidazolate frameworks (ZIF-67) are used not only as the morphological template but also as the cobalt precursor. During the two-step temperature-raising hydrothermal process, ZIF-67 polyhedrons are first transformed to hollow cobalt sulfide polyhedrons by sulfidation, and then molybdenum disulfide nanosheets further grow and deposit on the surface of hollow cobalt sulfide polyhedrons at the increased temperature. The crystalline hollow Co3S4@MoS2 heterostructures are finally obtained after subsequent thermal annealing under a N2 atmosphere. Due to the synergistic effects between the hydrogen evolution reaction active catalyst of MoS2 and the oxygen evolution reaction active catalyst of Co3S4, the obtained hollow Co3S4@MoS2 heterostructures exhibit outstanding bifunctional ...
467 citations
TL;DR: In this paper, a layered-type LiV3O8 (LVO) was proposed as a prospective intercalation cathode for zinc-ion batteries with high storage capacities.
Abstract: Rechargeable zinc-ion batteries (ZIBs) with high energy densities appear promising to meet the increasing demand for safe and sustainable energy storage devices. However, electrode research on this low-cost and green system are faced with stiff challenges of identifying materials that permit divalent ion-intercalation/deintercalation. Herein, we present layered-type LiV3O8 (LVO) as a prospective intercalation cathode for zinc-ion batteries (ZIBs) with high storage capacities. The detailed phase evolution study during Zn intercalation using electrochemistry, in situ XRD, and simulation techniques reveals the large presence of a single-phase domain that proceeds via a stoichiometric ZnLiV3O8 phase to reversible solid–solution ZnyLiV3O8 (y > 1) phase. The unique behavior, which is different from the reaction with lithium, contributes to high specific capacities of 172 mAh g–1 and amounts to 75% retention of the maximum capacity achieved in 65 cycles with 100% Coulombic efficiency at a current density of 133 ...
TL;DR: An overview of the current best practices associated with the synthesis, activation, and characterization of metal-organic frameworks (MOFs) can be found in this article, where a variety of different MOFs are presented to aid in the discussion of relevant techniques.
Abstract: Metal–organic frameworks (MOFs) are structurally diverse materials comprised of inorganic and organic components. As the rapidly expanding field of MOF research has demonstrated, these materials are being explored for a wide variety of potential applications. In this tutorial review, we give an overview of the current best practices associated with the synthesis, activation, and characterization of MOFs. Methods described include supercritical CO2 activation, single crystal X-ray diffraction (XRD), powder X-ray diffraction (PXRD), nitrogen adsorption/desorption isotherms, surface area calculations, aqueous stability tests, scanning electron microscopy (SEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), nuclear magnetic resonance spectroscopy (NMR), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). A variety of different MOFs are presented to aid in the discussion of relevant techniques. In addition, some sections are accompanied by instructional videos to giv...
TL;DR: In this article, the authors report a series of procedures and measurement techniques that have adopted or developed to assess each of the above challenges in understanding materials for the oxygen evolution reaction (OER).
Abstract: Heterogeneous electrocatalysts for the oxygen evolution reaction (OER) are complicated materials with dynamic structures. They can exhibit potential-induced phase transitions, potential-dependent electronic properties, variable oxidation and protonation states, and disordered local/surface phases. These properties make understanding the OER, and ultimately designing higher efficiency catalysts, challenging. We report a series of procedures and measurement techniques that we have adopted or developed to assess each of the above challenges in understanding materials for the OER. These include the targeted synthesis of hydrated oxyhydroxide phases, the assessment and elimination of electrolyte impurities, the use of a quartz crystal microbalance to monitor film loading and dissolution, and the use of an in situ conductivity measurement to understand the flow of electrons from the catalyst active sites to the conductive support electrode. We end with a recipe for the synthesis and characterization of a “stand...
TL;DR: In this article, the optical and electronic properties of single crystals of the widebandgap semiconducting defect halide perovskites A3M2I9 (A = Cs, Rb; M = Bi, Sb) have been investigated.
Abstract: The optical and electronic properties of Bridgman grown single crystals of the wide-bandgap semiconducting defect halide perovskites A3M2I9 (A = Cs, Rb; M = Bi, Sb) have been investigated. Intense Raman scattering was observed at room temperature for each compound, indicating high polarizability and strong electron–phonon coupling. Both low-temperature and room-temperature photoluminescence (PL) were measured for each compound. Cs3Sb2I9 and Rb3Sb2I9 have broad PL emission bands between 1.75 and 2.05 eV with peaks at 1.96 and 1.92 eV, respectively. The Cs3Bi2I9 PL spectra showed broad emission consisting of several overlapping bands in the 1.65–2.2 eV range. Evidence of strong electron–phonon coupling comparable to that of the alkali halides was observed in phonon broadening of the PL emission. Effective phonon energies obtained from temperature-dependent PL measurements were in agreement with the Raman peak energies. A model is proposed whereby electron–phonon interactions in Cs3Sb2I9, Rb3Sb2I9, and Cs3Bi...
TL;DR: In this paper, the authors discuss the rational behind a chosen experimental procedure in full detail using standard “Methods” sections due to the frequent use of procedures developed in related prior reports.
Abstract: Liquid phase exfoliation has become an important method for the production of large quantities of two-dimensional (2D) nanosheets. This method is versatile, having been used to produce dozens of different 2D materials in a range of stabilizing liquids. The resultant liquid-suspended nanosheets have been characterized in great detail and have been processed into a number of structures for a wide range of applications. This has led to a growing number of researchers adopting this method. As a result, best practice in terms of experimental procedure has evolved rapidly over recent years. As experimental complexity has increased, it has become more and more difficult to discuss the rational behind a chosen experimental procedure in full detail using standard “Methods” sections due to the frequent use of procedures developed in related prior reports. This can make it difficult to reproduce complex procedures and acts as a barrier to new researchers entering the field. To address this shortcoming, here we descr...
TL;DR: In this article, the interface stability of argyrodite Li6PS5Cl was investigated for all-solid-state Li-ion half-cells and the interface mechanisms were characterized by Auger electron spectroscopy and X-ray photoelectron spectrographs.
Abstract: Argyrodite Li6PS5Cl is a good candidate for being a solid electrolyte for bulk all-solid-state Li-ion batteries because of its high ionic conductivity and its good processability. However, the interface stability of sulfide-based electrolytes toward active materials (negative or positive electrodes) is known to be lower than that of oxide-based electrolytes. In this work, we investigate the interface stability of argyrodite toward several positive electrode materials: LiCoO2, LiNi1/3Co1/3Mn1/3O2, and LiMn2O4. All-solid-state half-cells were cycled, and the interface mechanisms were characterized by Auger electron spectroscopy and X-ray photoelectron spectroscopy. We show that Li6PS5Cl is oxidized into elemental sulfur, lithium polysulfides, P2Sx (x ≥ 5), phosphates, and LiCl at the interface with the positive electrode active materials. In spite of this interface reactivity, good capacity retention was observed over 300 cycles. Li6PS5Cl shows some reversible electrochemical activity (redox processes) that...
TL;DR: In this paper, the authors developed a methodology to automatically compile materials synthesis parameters across tens of thousands of scholarly publications using natural language processing techniques and applied machine learning methods to predict the critical parameters needed to synthesize titania nanotubes via hydrothermal methods and verify this result against known mechanisms.
Abstract: In the past several years, Materials Genome Initiative (MGI) efforts have produced myriad examples of computationally designed materials in the fields of energy storage, catalysis, thermoelectrics, and hydrogen storage as well as large data resources that are used to screen for potentially transformative compounds. The bottleneck in high-throughput materials design has thus shifted to materials synthesis, which motivates our development of a methodology to automatically compile materials synthesis parameters across tens of thousands of scholarly publications using natural language processing techniques. To demonstrate our framework’s capabilities, we examine the synthesis conditions for various metal oxides across more than 12 thousand manuscripts. We then apply machine learning methods to predict the critical parameters needed to synthesize titania nanotubes via hydrothermal methods and verify this result against known mechanisms. Finally, we demonstrate the capacity for transfer learning by using machin...
TL;DR: In this paper, the Ni-rich layered [Ni0.90Co0.05Mn0.2]O2 cathode has been synthesized and its electrochemical performance in lithium-ion cells has been benchmarked against a lower-Ni content Li[Ni 0.6Co 0.3 V], making it an appealing candidate for electric vehicles.
Abstract: To address the growing demand for energy density, the Ni-rich layered [Ni0.90Co0.05Mn0.05]O2 cathode has been synthesized and its electrochemical performance in lithium-ion cells has been benchmarked against a lower-Ni content Li[Ni0.6Co0.2Mn0.2]O2 cathode. Li[Ni0.90Co0.05Mn0.05]O2 delivers a high discharge capacity of 227 mA h g–1 compared to a capacity of 189 mA h g–1 for Li[Ni0.6Co0.2Mn0.2]O2 when cycled up to a lower cutoff voltage of 4.3 V, making it an appealing candidate for electric vehicles. With an increase in the charge cutoff voltage to 4.5 V, Li[Ni0.90Co0.05Mn0.05]O2 displays a capacity of 238 mA h g–1 compared to a capacity of 208 mA h g–1 for Li[Ni0.6Co0.2Mn0.2]O2. Although Li[Ni0.90Co0.05Mn0.05]O2 suffers during cycling from the usual rapid capacity fade in a manner similar to that of LiNiO2, 87 and 81% of the initial capacity could still be retained after 100 cycles even after cycling to higher cutoff voltages of 4.3 and 4.5 V, respectively. A comparison of Li[Ni0.90Co0.05Mn0.05]O2 and Li...
TL;DR: In this paper, a room-temperature solution-based synthesis for UiO-66 and several of its derivatives, Uo-66-X (X = NH2, OH, or NO2), is reported, resulting in materials that are as porous and crystalline as those made at elevated temperatures.
Abstract: UiO-66 is an archetypal zirconium-based metal–organic framework (MOF) that is constructed from hexanuclear zirconium oxide clusters as secondary building units (SBUs) and 1,4-benzenedicarboxylate (bdc) linkers. For the first time, a room-temperature solution-based synthesis is reported for UiO-66 and several of its derivatives, UiO-66-X (X = NH2, OH, or NO2), resulting in materials that are as porous and crystalline as those made at elevated temperatures. In addition, via modulation of the temperature at which UiO-66 is synthesized, the number of defect sites can be varied. It was found through N2 sorption isotherm analysis and potentiometric acid–base titrations that increasing the synthesis temperature from 25 to 130 °C results in a systematic decrease in the number of defect sites in UiO-66. The results suggest that, with respect to this synthetic procedure, a maximal number of defect sites is achieved [∼1.3 missing linkers per Zr6O4(OH)4(bdc)6] at a temperature of 45 °C.
TL;DR: In this article, the authors highlight how nanocellulose (NC) is being tailored and applied in (bio)sensing technology, whose results aim at displaying analytical information related to various fields such as clinical/medical diagnostics, environmental monitoring, food safety, physical/mechanical sensing, labeling and bioimaging appli...
Abstract: Because of its multifunctional character, nanocellulose (NC) is one of the most interesting nature-based nanomaterials and is attracting attention in a myriad of fields such as biomaterials, engineering, biomedicine, opto/electronic devices, nanocomposites, textiles, cosmetics and food products. Moreover, NC offers a plethora of outstanding properties, including inherent renewability, biodegradability, commercial availability, flexibility, printability, low density, high porosity, optical transparency as well as extraordinary mechanical, thermal and physicochemical properties. Consequently, NC holds unprecedented capabilities that are appealing to the scientific, technologic and industrial community. In this review, we highlight how NC is being tailored and applied in (bio)sensing technology, whose results aim at displaying analytical information related to various fields such as clinical/medical diagnostics, environmental monitoring, food safety, physical/mechanical sensing, labeling and bioimaging appli...
TL;DR: In this paper, a novel CsPbBr3 NCs room-temperature synthesis based on Cs acetate, which displays near-unity photoluminescence (PL) quantum yield (PL) and color tunability.
Abstract: Metal halide perovskite nanocrystals (NCs) possess high photoluminescence (PL) quantum yield (PL) and color tunability. Yet, until now, it has been difficult to maintain the high PL observed in solution in spin-coated films. Here, we report a novel CsPbBr3 NCs room-temperature synthesis based on Cs acetate, which displays near-unity PL in solid-state films upon post-synthetic treatment with lead bromide. The as-synthesized NCs show a PL of 80% in spin-coated films but the post-synthesis treatment further enhances the efficiency >95%. The high PL is further confirmed by the monomolecular decay of the PL (5.8 ns) indicating a nearly complete suppression of non-radiative channels. The obtained films demonstrate high stability in air and require around 3 weeks to decrease to half the initial PL value.
TL;DR: In this article, the authors presented a methodology to measure the alkaline stability of anion conducting polymers to be used as anion exchange membranes and ion exchange ionomers for fuel cells.
Abstract: Here we present a novel methodology to measure the alkaline stability of anion conducting polymers to be used as anion exchange membranes and anion exchange ionomers for fuel cells. The new ex situ technique simulates the environment of an anion exchange membrane fuel cell (AEMFC) during operation, where nucleophilic and basic OH– species in the absence, or with a scarce amount of water, attack the functional groups of the ionic polymer. Using this technique, we clearly show the critical effect of water molecules on the alkaline stability of quaternary ammonium (QA) cations commonly used as functional groups in AEMFCs. The results show that as the water content is reduced, the QA cations are more rapidly degraded in the presence of OH– at room temperature. With an increasing number of water molecules solvating the hydroxide, its nucleophilicity and basicity are hindered, and the QA degradation is significantly slowed. These results indicate that the currently used aqueous alkali ex situ tests to measure a...
TL;DR: These MnOx/Ti3C2 composite MXenes have been developed as multifunctional theranostic agents for efficient magnetic resonance (MR) and photoacoustic (PA) dual-modality imaging-guided photothermal therapy (PTT) against cancer.
Abstract: The emerging of two-dimensional (2D) MXenes significantly broadens the family members and versatile applications of 2D materials, but the rational design of MXene-based composites and their specific applications in theranostic biomedicine are still challenging. In this work, we report, for the first time, on the elaborate design of the Ti3C2-based composite MXene (MnOx/Ti3C2) for highly efficient theranostic applications against cancer. These MnOx/Ti3C2 composite MXenes have been constructed by triggering a simple redox reaction to in situ grow small MnOx nanosheets on the surface of Ti3C2. These MnOx/Ti3C2 composite MXenes have been developed as multifunctional theranostic agents for efficient magnetic resonance (MR) and photoacoustic (PA) dual-modality imaging-guided photothermal therapy (PTT) against cancer. Especially, the decoration of the MnOx component onto MnOx/Ti3C2 realizes the unique tumor microenvironment-responsive T1-weighted MR imaging of tumors, and the high photothermal-conversion perform...
TL;DR: In this article, a hybrid double perovskite, (MA)2AgBiBr6, was synthesized with a low band gap of 2.02 eV.
Abstract: The discovery of lead-free hybrid double perovskites provides a viable approach in the search for stable and environmentally benign photovoltaic materials as alternatives to lead-containing systems such as MAPbX3 (X = Cl, Br, or I). Following our recent reports of (MA)2KBiCl6 and (MA)2TlBiBr6, we have now synthesized a hybrid double perovskite, (MA)2AgBiBr6, that has a low band gap of 2.02 eV and is relatively stable and nontoxic. Its electronic structure and mechanical and optical properties are investigated with a combination of experimental studies and density functional theory calculations.
TL;DR: In this paper, porous multishelled Ni2P hollow microspheres assembled by nanoparticles were prepared through a simple and economical self-templating approach followed by phosphorization.
Abstract: Tailoring the morphology and microstructure of electrocatalysts is important in improving catalytic performance. Herein, porous multishelled Ni2P hollow microspheres assembled by nanoparticles were prepared through a simple and economical self-templating approach followed by phosphorization. Compared with nanoparticles and hierarchical solid-interior microspheres, the synthesized multishelled, hollow microstructures of Ni2P exhibit significantly higher electrocatalytic activity for the hydrogen evolution reaction in a 1 M KOH electrolyte. Additionally, a NiOOH layer is formed on the surface of Ni2P during anodic polarization, as revealed by electron microscopy, X-ray photoelectron spectroscopy, and in situ Raman analysis. The Ni2P/NiOOH derivative outperforms the benchmark RuO2 in catalyzing the oxygen evolution reaction. Furthermore, pairing the carbon fiber paper-supported multishelled Ni2P as both the anode and cathode results in superior overall alkaline water splitting performance, generating 10 and ...
TL;DR: The field of organic electronics has been heavily impacted by the discovery and development of π-conjugated conducting polymers as mentioned in this paper, and polythiophene and its derivatives have been widely investigated computationally and experimentally for use in electronic devices such as light-emitting diodes, water purification devices, hydrogen storage, and biosensors.
Abstract: The field of organic electronics has been heavily impacted by the discovery and development of π-conjugated conducting polymers. These polymers show great potential for integration into future optical and electronic devices due to their capacity to transition between semiconducting and conducting states as well as the ability to alter mechanical properties by controlled doping, chemical modification, and stacking or creating composites with other materials. Among π-conjugated polymers, polythiophene and its derivatives has been one of the most extensively studied and is widely investigated computationally and experimentally for use in electronic devices such as light-emitting diodes, water purification devices, hydrogen storage, and biosensors. Various theoretical modeling studies of polythiophene ranging from an oligothiophene approach to infinite chain lengths (periodic boundary conditions) have been undertaken to study a variety of electronic and structural properties of these polymers. In this review,...
TL;DR: This Review highlights the application of solid-state nuclear magnetic resonance (NMR) spectroscopy in battery research: a technique that can be extremely powerful in characterizing local structures in battery materials, even in highly disordered systems.
Abstract: Improving electrochemical energy storage is one of the major issues of our time The search for new battery materials together with the drive to improve performance and lower cost of existing and new batteries is not without its challenges Success in these matters is undoubtedly based on first understanding the underlying chemistries of the materials and the relations between the components involved A combined application of experimental and theoretical techniques has proven to be a powerful strategy to gain insights into many of the questions that arise from the “how do batteries work and why do they fail” challenge In this Review, we highlight the application of solid-state nuclear magnetic resonance (NMR) spectroscopy in battery research: a technique that can be extremely powerful in characterizing local structures in battery materials, even in highly disordered systems An introduction on electrochemical energy storage illustrates the research aims and prospective approaches to reach these We part
TL;DR: In this paper, the authors demonstrate a heteronanostructure for hydrogen evolution reaction, which consists of metallic 1T-MoS2 nanopatches grown on the surface of flexible single-walled carbon nanotube (SWNT) films.
Abstract: Designing advanced electrocatalysts for hydrogen evolution reaction is of far-reaching significance. Active sites and conductivity play vital roles in such a process. Herein, we demonstrate a heteronanostructure for hydrogen evolution reaction, which consists of metallic 1T-MoS2 nanopatches grown on the surface of flexible single-walled carbon nanotube (1T-MoS2/SWNT) films. The simulated deformation charge density of the interface shows that 0.924 electron can be transferred from SWNT to 1T-MoS2, which weakens the absorption energy of H atom on electron-doped 1T-MoS2, resulting in superior electrocatalytic performance. The electron doping effect via interface engineering renders this heteronanostructure material outstanding hydrogen evolution reaction (HER) activity with initial overpotential as small as approximately 40 mV, a low Tafel slope of 36 mV/dec, 108 mV for 10 mA/cm2, and excellent stability. We propose that such interface engineering could be widely used to develop new catalysts for energy conv...
TL;DR: In this paper, the authors proposed screening criteria for defect-tolerant photovoltaic (PV) absorbers, identifying several classes of semiconducting compounds with electronic structures similar to those of hybrid lead-halide perovskites.
Abstract: Recently, we and others have proposed screening criteria for “defect-tolerant” photovoltaic (PV) absorbers, identifying several classes of semiconducting compounds with electronic structures similar to those of hybrid lead–halide perovskites. In this work, we reflect on the accuracy and prospects of these new design criteria through a combined experimental and theoretical approach. We construct a model to extract photoluminescence lifetimes of six of these candidate PV absorbers, including four (InI, SbSI, SbSeI, and BiOI) for which time-resolved photoluminescence has not been previously reported. The lifetimes of all six candidate materials exceed 1 ns, a threshold for promising early stage PV device performance. However, there are variations between these materials, and none achieve lifetimes as high as those of the hybrid lead–halide perovskites, suggesting that the heuristics for defect-tolerant semiconductors are incomplete. We explore this through first-principles point defect calculations and Shock...