Showing papers by "Zhen Li published in 2017"
TL;DR: A new deep learning method that predicts contacts by integrating both evolutionary coupling (EC) and sequence conservation information through an ultra-deep neural network formed by two deep residual neural networks that greatly outperforms existing methods and leads to much more accurate contact-assisted folding.
Abstract: Motivation Protein contacts contain key information for the understanding of protein structure and function and thus, contact prediction from sequence is an important problem. Recently exciting progress has been made on this problem, but the predicted contacts for proteins without many sequence homologs is still of low quality and not very useful for de novo structure prediction. Method This paper presents a new deep learning method that predicts contacts by integrating both evolutionary coupling (EC) and sequence conservation information through an ultra-deep neural network formed by two deep residual neural networks. The first residual network conducts a series of 1-dimensional convolutional transformation of sequential features; the second residual network conducts a series of 2-dimensional convolutional transformation of pairwise information including output of the first residual network, EC information and pairwise potential. By using very deep residual networks, we can accurately model contact occurrence patterns and complex sequence-structure relationship and thus, obtain higher-quality contact prediction regardless of how many sequence homologs are available for proteins in question. Results Our method greatly outperforms existing methods and leads to much more accurate contact-assisted folding. Tested on 105 CASP11 targets, 76 past CAMEO hard targets, and 398 membrane proteins, the average top L long-range prediction accuracy obtained by our method, one representative EC method CCMpred and the CASP11 winner MetaPSICOV is 0.47, 0.21 and 0.30, respectively; the average top L/10 long-range accuracy of our method, CCMpred and MetaPSICOV is 0.77, 0.47 and 0.59, respectively. Ab initio folding using our predicted contacts as restraints but without any force fields can yield correct folds (i.e., TMscore>0.6) for 203 of the 579 test proteins, while that using MetaPSICOV- and CCMpred-predicted contacts can do so for only 79 and 62 of them, respectively. Our contact-assisted models also have much better quality than template-based models especially for membrane proteins. The 3D models built from our contact prediction have TMscore>0.5 for 208 of the 398 membrane proteins, while those from homology modeling have TMscore>0.5 for only 10 of them. Further, even if trained mostly by soluble proteins, our deep learning method works very well on membrane proteins. In the recent blind CAMEO benchmark, our fully-automated web server implementing this method successfully folded 6 targets with a new fold and only 0.3L-2.3L effective sequence homologs, including one β protein of 182 residues, one α+β protein of 125 residues, one α protein of 140 residues, one α protein of 217 residues, one α/β of 260 residues and one α protein of 462 residues. Our method also achieved the highest F1 score on free-modeling targets in the latest CASP (Critical Assessment of Structure Prediction), although it was not fully implemented back then. Availability http://raptorx.uchicago.edu/ContactMap/
779 citations
TL;DR: In this paper, the authors focus on the significant advances in tailored nanostructures of noble metal-metal oxide nanohybrids and highlight the improvement in performance in the representative solar energy conversion applications.
Abstract: The controlled synthesis of nanohybrids composed of noble metals (Au, Ag, Pt and Pd, as well as AuAg alloy) and metal oxides (ZnO, TiO2, Cu2O and CeO2) have received considerable attention for applications in photocatalysis, solar cells, drug delivery, surface enhanced Raman spectroscopy and many other important areas. The overall architecture of nanocomposites is one of the most important factors dictating the physical properties of nanohybrids. Noble metals can be coupled to metal oxides to yield diversified nanostructures, including noble metal decorated-metal oxide nanoparticles (NPs), nanoarrays, noble metal/metal oxide core/shell, noble metal/metal oxide yolk/shell and Janus noble metal–metal oxide nanostructures. In this review, we focus on the significant advances in tailored nanostructures of noble metal–metal oxide nanohybrids. The improvement in performance in the representative solar energy conversion applications including photocatalytic degradation of organic pollutants, photocatalytic hydrogen generation, photocatalytic CO2 reduction, dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs) are discussed. Finally, we conclude with a perspective on the future direction and prospects of these controllable nanohybrid materials.
756 citations
TL;DR: Yang et al. as discussed by the authors developed an ink formulation which gives similar devices by spin coating, the lab-scale standard, and blade coating, which is a more scalable, industry-relevant deposition method.
Abstract: Perovskite solar cells have made tremendous progress using laboratory-scale spin-coating methods in the past few years owing to advances in controls of perovskite film deposition. However, devices made via scalable methods are still lagging behind state-of-the-art spin-coated devices because of the complicated nature of perovskite crystallization from a precursor state. Here we demonstrate a chlorine-containing methylammonium lead iodide precursor formulation along with solvent tuning to enable a wide precursor-processing window (up to ∼8 min) and a rapid grain growth rate (as short as ∼1 min). Coupled with antisolvent extraction, this precursor ink delivers high-quality perovskite films with large-scale uniformity. The ink can be used by both spin-coating and blade-coating methods with indistinguishable film morphology and device performance. Using a blade-coated absorber, devices with 0.12-cm2 and 1.2-cm2 areas yield average efficiencies of 18.55% and 17.33%, respectively. We further demonstrate a 12.6-cm2 four-cell module (88% geometric fill factor) with 13.3% stabilized active-area efficiency output. Perovskite-based solar cells are often fabricated by methods that are not industrially scalable. Here, Yang et al. develop an ink formulation which gives similar devices by spin coating, the lab-scale standard, and blade coating, which is a more scalable, industry-relevant deposition method.
463 citations
TL;DR: In this paper, a review of MCF materials with distinct emission properties and various molecular arrangements is presented, focusing on the inherent correlation between molecular packing modes and emissive behaviors.
Abstract: Mechanochromic fluorescence (MCF) materials are a sort of smart material whose photophysical properties are sensitive to mechanical stimulation, such as photoluminescence color, fluorescence quantum yield and emission lifetime. Recently, an increasing number of studies have shown that these photophysical properties can be affected greatly by the molecular packing and conformation, enabling the rapid development of functional materials with mechanochromic fluorescence properties. In this review, we focus on MCF materials with distinct emission properties and various molecular arrangements, especially the inherent correlation between molecular packing modes and emissive behaviors. Many of the selected representative examples possess polymorphism, offering the possibility of exploring different emissions from the exact molecular packing in single crystals. Correspondingly, some remarks are made on the outlook for the next developments in MCF materials and the required thinking about the structure–packing–performance relationship.
432 citations
TL;DR: With the consideration of all these parameters, the strong fluorescence and phosphorescence in the aggregated state could be achieved in the rationally designed organic luminogens, providing some guidance for the further development.
Abstract: The strong light emission of organic luminogens in the aggregated state is essential to their applications as optoelectronic materials with good performance. In this review, with respect to the aggregation-induced emission and room-temperature phosphorescence luminogens, the important role of molecular packing modes is highlighted. As demonstrated in the selected examples, the molecular packing status in the aggregate state is affected by many factors, including the molecular configurations, the inherent electronic properties, the special functional groups, and so on. With the consideration of all these parameters, the strong fluorescence and phosphorescence in the aggregated state could be achieved in the rationally designed organic luminogens, providing some guidance for the further development.
420 citations
TL;DR: In this paper, the authors demonstrate that extrinsic ions (e.g., Li+, H+, Na+), when used in the contact layers in PSCs, can migrate across the perovskite layer and strongly impact PSC operation.
Abstract: The migration of intrinsic ions (e.g., MA+, Pb2+, I−) in organic–inorganic hybrid perovskites has received significant attention with respect to the critical roles of these ions in the hysteresis and degradation in perovskite solar cells (PSCs). Here, we demonstrate that extrinsic ions (e.g., Li+, H+, Na+), when used in the contact layers in PSCs, can migrate across the perovskite layer and strongly impact PSC operation. In a TiO2/perovskite/spiro-OMeTAD-based PSC, Li+-ion migration from spiro-OMeTAD to the perovskite and TiO2 layer is illustrated by time-of-flight secondary-ion mass spectrometry. The movement of Li+ ions in PSCs plays an important role in modulating the solar cell performance, tuning TiO2 carrier-extraction properties, and affecting hysteresis in PSCs. The influence of Li+-ion migration was investigated using time-resolved photoluminescence, Kelvin probe force microscopy, and external quantum efficiency spectra. Other extrinsic ions such as H+ and Na+ also show a clear impact on the performance and hysteresis in PSCs. Understanding the impacts of extrinsic ions in perovskite-based devices could lead to new material and device designs to further advance perovskite technology for various applications.
415 citations
TL;DR: By investigating the molecular packing arrangement in single crystals, it is found that the packing style of the compact face to face favors of long phosphorescence lifetime and high photoluminescence efficiency, with the lifetime up to 748 ms observed in the crystal of CPM.
Abstract: Long-lived phosphorescence at room temperature (RTP) from pure organic molecules is rare. Recent research reveals various crystalline organic molecules can realize RTP with lifetimes extending to the magnitude of second. There is little research on how molecular packing affecting RTP. Three compounds are designed with similar optical properties in solution, but tremendously different solid emission characteristics. By investigating the molecular packing arrangement in single crystals, it is found that the packing style of the compact face to face favors of long phosphorescence lifetime and high photoluminescence efficiency, with the lifetime up to 748 ms observed in the crystal of CPM ((9H-carbazol-9-yl)(phenyl)methanone). Theoretical calculation analysis also reveals this kind of packing style can remarkably reduce the singlet excited energy level and prompt electron communication between dimers. Surprisingly, CPM has two very similar single crystals, labeled as CPM and CPM-A, with almost identical crystal data, and the only difference is that molecules in CPM-A crystal take a little looser packing arrangement. X-ray diffraction and cross-polarization under magic spinning 13 C NMR spectra double confirm that they are different crystals. Interestingly, CPM-A crystal shows negligible RTP compared to the CPM crystal, once again proving that the packing style is critical to the RTP property.
328 citations
22 Sep 2017
TL;DR: This work proposes a data-driven method for recovering missing parts of 3D shapes based on a new deep learning architecture consisting of a global structure inference network and a local geometry refinement network that outperforms existing state-of-the-art work on shape completion.
Abstract: We propose a data-driven method for recovering missing parts of 3D shapes. Our method is based on a new deep learning architecture consisting of two sub-networks: a global structure inference network and a local geometry refinement network. The global structure inference network incorporates a long short-term memorized context fusion module (LSTM-CF) that infers the global structure of the shape based on multi-view depth information provided as part of the input. It also includes a 3D fully convolutional (3DFCN) module that further enriches the global structure representation according to volumetric information in the input. Under the guidance of the global structure network, the local geometry refinement network takes as input local 3D patches around missing regions, and progressively produces a high-resolution, complete surface through a volumetric encoder-decoder architecture. Our method jointly trains the global structure inference and local geometry refinement networks in an end-to-end manner. We perform qualitative and quantitative evaluations on six object categories, demonstrating that our method outperforms existing state-of-the-art work on shape completion.
282 citations
TL;DR: In this paper, a hierarchical structure for high-sulfur-loading electrodes is proposed, where titanium monoxide hollow nanospheres are packed space efficiently and closely connected by carbon layers into micro-sized "clusters" as the sulfur host, and the nanoscale reaction chambers and the microscale conductive networks cooperatively promise high capacities of sulfur at various current densities.
235 citations
TL;DR: The first example of an AIEgen (DPP-BO) with fluorescence-phosphorescence dual emission under mechanical stimulation is reported, possibly opening up a new way to study the inherent mechanism of ML by broadening the application of AIEgens.
Abstract: We report the first example of an AIEgen (DPP-BO) with fluorescence-phosphorescence dual emission under mechanical stimulation. By carefully analyzing the crystal structure of DPP-BO, the efficient intermolecular and intramolecular interactions should account for its unique mechanoluminescence (ML) properties, especially the abnormal phosphorescence, as further confirmed by controlled experiments and theoretical calculations for the presence of ISC transitions. These results provide important information for understanding the complex ML process, possibly opening up a new way to study the inherent mechanism of ML by broadening the application of AIEgens.
232 citations
TL;DR: In this paper, a controllable solvothermal method was developed to grow intrinsically conductive MoS2 nanosheet arrays in a metastable 1T phase on carbon fiber cloth (CFC) as binder-free, high activity Li-ion battery (LIB) anodes.
Abstract: We have developed a controllable solvothermal method to grow intrinsically conductive MoS2 nanosheet arrays in a metastable 1T phase on carbon fiber cloth (CFC) as binder-free, high-activity Li-ion battery (LIB) anodes By introducing surface hydroxyl groups on the CFC and tuning the DMF content in the mixed solvent, MoS2 nanosheet arrays were perpendicularly grown to the surface of the carbon fibers with a high coverage Electrochemical measurements reveal that the 1T phase nanosheet arrays have excellent Li-ion storage performances, including high specific capacity, high rate capability and good cycling stability, outperforming 2H phase arrays Because of the metallic 1T phase and the highly oriented array architecture, after subtracting the total capacity of CFC, the 1T arrays also deliver a high reversible specific capacity of 1789 mA h g−1 at 01 A g−1 and a retained capacity of 853 mA h g−1 after 140 cycles at 1 A g−1
TL;DR: Careful analysis of the crystal structures shows that the formation and fracture of molecular dimers with intermolecular charge-transfer properties has a significant effect on intersystem crossing, as well as excited triplet state emissions, in both PL and ML processes.
Abstract: Two stable, purely organic luminogens exhibit both mechano- (ML) and photoluminescence (PL) with dual fluorescence–phosphorescence emissions at room temperature. Careful analysis of the crystal structures, coupled with theoretical calculations, demonstrate that room-temperature phosphorescence and ML properties are strongly related to molecular packing. In particular, the formation and fracture of molecular dimers with intermolecular charge-transfer properties has a significant effect on intersystem crossing, as well as excited triplet state emissions, in both PL and ML processes.
TL;DR: The resultant CuFeSe2 nanocrystals show superparamagnetism and effective attenuation for X-rays, and exhibit excellent water solubility, colloidal stability, biocompatibility, and multifunctional groups, enabling them to be an ideal nanotheranostic agent for multimodal imaging.
Abstract: Nanoscale ternary chalcogenides have attracted intense research interest due to their wealth of tunable properties and diverse applications in energy and environmental and biomedical fields. In this article, ultrasmall magnetic CuFeSe2 ternary nanocrystals (<5.0 nm) were fabricated in the presence of thiol-functionalized poly(methacrylic acid) by an environmentally friendly aqueous method under ambient conditions. The small band gap and the existence of intermediate bands lead to a broad NIR absorbance in the range of 500–1100 nm and high photothermal conversion efficiency (82%) of CuFeSe2 nanocrystals. The resultant CuFeSe2 nanocrystals show superparamagnetism and effective attenuation for X-rays. In addition, they also exhibit excellent water solubility, colloidal stability, biocompatibility, and multifunctional groups. These properties enable them to be an ideal nanotheranostic agent for multimodal imaging [e.g., photoacoustic imaging (PAI), magnetic resonance imaging (MRI), computed tomography (CT) im...
TL;DR: In this paper, a modified Pt-TiO2/CdS photocatalyst was applied in photocatalytic overall water splitting system to remove newly formed oxygen from catalyst surface mainly inhibiting the hydrogen and oxygen back recombination to water.
Abstract: CdS is a well-known and important visible-light responsive photocatalyst for overall water splitting. However, the serious photocorrosion property limits its application in photocatalysis. Through modification TiO2 thin film over CdS surface, TiO2/CdS photocatalyst exhibited an obviously enhanced photocatalytic stability. The H2 evolution rate (3.074 μmol h−1 g−1) of modified Pt-TiO2/CdS under visible light toward overall water splitting was almost 6 times higher than that of CdS sample (0.534 μmol h−1 g−1). The application of artificial gill in photocatalytic overall water splitting system removed the newly formed oxygen from catalyst surface mainly inhibiting the hydrogen and oxygen back recombination to water and preventing the oxygen led oxidation or photocorrosion. By these two strategies, we fulfilled visible light induced overall water splitting in CdS dispersion and achieved satisfied stability during reaction.
TL;DR: In this article, a series of boron-containing phosphors were found to present RTP with long-lived lifetimes, and they were used as an additive to feed Bombyx mori silkworms and showed low toxicity over inorganic materials.
Abstract: Purely organic materials with the characteristic of room-temperature phosphorescence (RTP) under ambient conditions demonstrate potential benefits in advanced optoelectronic applications. Exploration of versatile and efficient RTP compounds with low prices is full of challenges due to the slow intersystem crossing process and ultrafast deactivation of the active excited states of organic compounds. Here, a series of boron-containing phosphors were found to present RTP with long-lived lifetimes. Among these commercially available and cheap compounds, (4-methoxyphenyl)boronic acid (PBA-MeO) exhibits long-lived RTP, with a lifetime of 2.24 s, which is among the longest lifetimes of single-component small molecules. Our extensive experiments illustrate that both a rigid conformation and expanded conjugation induced by molecular alignment contribute to the persistent RTP. Because of strong intermolecular interactions via hydrogen bonds, these arylboronic acids easily form crystals and are quite appropriate for anti-forgery materials. Subsequently, we develop a precise, speedy and convenient inkjet printing technology for the fabrication of optoelectronic displays. Furthermore, PBA-MeO is used as an additive to feed Bombyx mori silkworms and shows low toxicity over inorganic materials. Our findings may pave a new way for the development of RTP phosphors and promote their use in practical applications.
TL;DR: Grain boundaries with respect to non-GB regions in high-quality micrometer-sized perovskite MAPbI3 thin films are examined using high-resolution confocal fluorescence-lifetime imaging microscopy in conjunction with kinetic modeling of charge-transport and recombination processes to show that GBs in these films do not lead to increased recombination.
Abstract: Here, we examine grain boundaries (GBs) with respect to non-GB regions (grain surfaces (GSs) and grain interiors (GIs)) in high-quality micrometer-sized perovskite CH3NH3PbI3 (or MAPbI3) thin films using high-resolution confocal fluorescence-lifetime imaging microscopy in conjunction with kinetic modeling of charge-transport and recombination processes. We show that, contrary to previous studies, GBs in our perovskite MAPbI3 thin films do not lead to increased recombination but that recombination in these films happens primarily in the non-GB regions (i.e., GSs or GIs). We also find that GBs in these films are not transparent to photogenerated carriers, which is likely associated with a potential barrier at GBs. Even though GBs generally display lower luminescence intensities than GSs/GIs, the lifetimes at GBs are no worse than those at GSs/GIs, further suggesting that GBs do not dominate non-radiative recombination in MAPbI3 thin films.
TL;DR: In this paper, three crystalline polymorphs of CzS-CN, which display much different properties of room temperature phosphorescence (RTP) and aggregation-induced emission (AIE), were reported.
Abstract: Polymorphism of organic molecules has received special attention, since the significantly different photophysical properties can provide important information to build a bridge between the micro- and macro-world. Here, we report three crystalline polymorphs of CzS-CN, which display much different properties of room temperature phosphorescence (RTP) and aggregation-induced emission (AIE). Due to their different molecular packings, the RTP lifetimes change from 266 ms to 41 ms, and then to 32 ms, accompanied by different photoluminescence quantum yields of crystals from 22.6% and 17.8% to 6.9%. Careful analyses of these crystal structures demonstrate that the properties are highly related to the packing mode and molecular configuration, regardless of the same chemical structure, thus disclosing some important clues to understand the structure–packing–property relationship of RTP and AIE performances.
TL;DR: In this article, six blue AIE luminogens are successfully synthesized, which exhibit sky blue (484 nm) to deep blue (444 nm) emissions in accordance with the different introduced aromatic substituents on the pyrene core and the different linkage modes.
Abstract: Six blue AIE luminogens, Py-2pTPE, Py-2mTPE, Py-2TP, Py-2TF, Py-2NTF and Py-2F, have been successfully synthesized, which exhibit sky blue (484 nm) to deep blue (444 nm) emissions in accordance with the different introduced aromatic substituents on the pyrene core and the different linkage modes. Furthermore, Py-2pTPE and Py-2mTPE show interesting mechanochromism effects, inherited from TPE-pBr and TPE-mBr, respectively. When fabricated as emitters in OLEDs, all of the six AIEgens demonstrate blue emissions and good EL performances, among which, Py-2TP shows the best device performance with an ηEQE,max up to 3.46% at a CIE coordinate of (0.15, 0.09).
TL;DR: A facile topotactic-oriented attachment (TOA) process to grow highly oriented perovskite films, featuring strong uniaxial-crystallographic texture, micrometer-grain morphology, high crystallinity, low trap density, and unprecedented 9 GHz charge-carrier mobility is demonstrated.
Abstract: Organic-inorganic perovskites with intriguing optical and electrical properties have attracted significant research interests due to their excellent performance in optoelectronic devices. Recent efforts on preparing uniform and large-grain polycrystalline perovskite films have led to enhanced carrier lifetime up to several microseconds. However, the mobility and trap densities of polycrystalline perovskite films are still significantly behind their single-crystal counterparts. Here, a facile topotactic-oriented attachment (TOA) process to grow highly oriented perovskite films, featuring strong uniaxial-crystallographic texture, micrometer-grain morphology, high crystallinity, low trap density (≈4 × 1014 cm-3 ), and unprecedented 9 GHz charge-carrier mobility (71 cm2 V-1 s-1 ), is demonstrated. TOA-perovskite-based n-i-p planar solar cells show minimal discrepancies between stabilized efficiency (19.0%) and reverse-scan efficiency (19.7%). The TOA process is also applicable for growing other state-of-the-art perovskite alloys, including triple-cation and mixed-halide perovskites.
TL;DR: Benefiting from the unique oil-solution properties, the as-prepared CQDs can be processed in thin film and device forms to meet the requirements of various applications, such as phosphor-based white-light LEDs.
Abstract: Carbon quantum dots (CQDs) have attracted much attention owing to their unique optical properties and a wide range of applications. The fabrication and control of CQDs with organic solubility and long-wavelength emission are still urgent issues to be addressed for their practical use in LEDs. Here, organic-soluble CQDs were produced at a high yield of ∼90% by a facile solvent engineering treatment of 1,3,6-trinitropyrene, which were simultaneously used as the nitrogen and carbon sources. The optical properties of the organic-soluble CQDs (o-CQDs) were investigated in nonpolar and polar solvents, films, and LED devices. The CQDs have a narrow size distribution around 2.66 nm, and can be dispersed in different organic solvents. Significantly, the as-prepared CQDs present an excitation-independent emission at 607 nm with fluorescence quantum yields (QYs) up to 65.93% in toluene solution. A pronounced solvent effect was observed and their strong absorption bands can be tuned in the whole visible region (400–750 nm) by changing the solvent. The CQDs in various solvents can emit bright, excitation-independent, long-wavelength fluorescence (orange to red). Furthermore, benefiting from the unique oil-solution properties, the as-prepared CQDs can be processed in thin film and device forms to meet the requirements of various applications, such as phosphor-based white-light LEDs. The color coordinate for these CQD modified LEDs is realized at (0.32, 0.31), which is close to pure white light (0.33, 0.33).
TL;DR: In this paper, Ni nanoparticles (NPs) encapsulated in a highly ordered MIL-101 as catalysts for CO2 methanation by double solvent method (DSM) and multiple impregnation method (IM).
TL;DR: A hollow mesoporous carbon@titanium nitride (HMC@TiN) host for loading 70 wt % of SeS2 as a cathode material for Li-SeS2 batteries exhibits promising areal capacity and stable cell performance in the high-mass-loading electrode.
Abstract: The introduction of a certain proportion of selenium into sulfur-based cathodes is an effective strategy for enhancing the integrated battery performance. However, similar to sulfur, selenium sulfide cathodes suffer from poor cycling stability owing to the dissolution of reaction intermediate products. In this study, to exploit the advantages of SeS2 to the full and avoid its shortcomings, we designed and synthesized a hollow mesoporous carbon@titanium nitride (HMC@TiN) host for loading 70 wt % of SeS2 as a cathode material for Li–SeS2 batteries. Benefiting from both physical and chemical entrapment by hollow mesoporous carbon and TiN, the HMC@TiN/SeS2 cathode manifests high utilization of the active material and excellent cycling stability. Moreover, it exhibits promising areal capacity (up to 4 mAh cm−2) with stable cell performance in the high-mass-loading electrode.
TL;DR: A freestanding lotus root-like carbon fiber network decorated with CoS2 nanoparticles has been designed and prepared as the SeS2 host for enhancing the lithium storage performance.
Abstract: SeS2 shows attractive advantages beyond bare S and Se as a cathode material for lithium storage. Here, a freestanding lotus root-like carbon fiber network decorated with CoS2 nanoparticles (denoted as CoS2@LRC) has been designed and prepared as the SeS2 host for enhancing the lithium storage performance. The integrated electrode is constructed by three-dimensional interconnected multichannel carbon fibers, which can not only accommodate high content of SeS2 (70 wt %), but also promise excellent electron and ion transport for achieving high capacity utilization of 1015 mAh g−1 at 0.2 A g−1. What is more, there are numerous CoS2 nanoparticles decorated all over the inner walls and surfaces of the carbon fibers, providing efficient sulfiphilic sites for restricting the dissolution of polysulfides and polyselenides during the electrochemical processes, thus successfully suppressing the shuttle effect and maintaining excellent cycling stability over 400 cycles at 0.5 A g−1.
TL;DR: In this article, a high-performance cathode material by confining 70 wt% of SeS2 in a highly ordered mesoporous carbon (CMK-3) framework with a polydopamine (PDA) protection sheath is reported.
Abstract: Selenium–sulfur solid solutions are a class of potential cathode materials for high energy batteries, since they have higher theoretical capacities than selenium and improved conductivity over sulfur. Here, a high-performance cathode material by confining 70 wt% of SeS2 in a highly ordered mesoporous carbon (CMK-3) framework with a polydopamine (PDA) protection sheath for novel Li–Se/S batteries is reported. With a relatively high SeS2 mass loading of 2.6–3 mg cm−2, the CMK-3/SeS2@PDA cathode exhibits a high capacity of >1200 mA h g−1 at 0.2 A g−1, excellent C-rate capability of 535 mA h g−1 at 5 A g−1, and prolonged life over 500 cycles. Benefitting from the unique advantages of SeS2 and the rationally designed host framework, this new cathode material demonstrates a feasible strategy to overcome the bottlenecks of current Li–S systems for high energy density rechargeable batteries.
TL;DR: In this article, the authors show that having a large grain size in the non-perovskite intermediate films is essential for the growth of high-quality α-FAPbI3(Cs) HOIP thin films.
Abstract: The δ → α phase transformation is a crucial step in the solution-growth process of formamidinium-based lead triiodide (FAPbI3) hybrid organic–inorganic perovskite (HOIP) thin films for perovskite solar cells (PSCs). Because the addition of cesium (Cs) stabilizes the α phase of FAPbI3-based HOIPs, here our research focuses on FAPbI3(Cs) thin films. We show that having a large grain size in the δ-FAPbI3(Cs) non-perovskite intermediate films is essential for the growth of high-quality α-FAPbI3(Cs) HOIP thin films. Here grain coarsening and phase transformation occur simultaneously during the thermal annealing step. A large starting grain size in the δ-FAPbI3(Cs) thin films suppresses grain coarsening, precluding the formation of voids at the final α-FAPbI3(Cs)–substrate interfaces. PSCs based on the interface void-free α-FAPbI3(Cs) HOIP thin films are much more efficient and stable in the ambient atmosphere. This interesting finding inspired us to develop a simple room-temperature aging method for preparing ...
TL;DR: An N-nitrosation reactivity-based two-Photon fluorescent probe for the specific detection of NO was rationally designed, prepared, and applied in the in situ detection of nitric oxide in ischemia reperfusion injury mouse model under two-photon microscopy for the first time.
Abstract: In situ fluorescence imaging of nitric oxide (NO) is a powerful tool for studying the critical roles of NO in biological events. However, the selective imaging of NO is still a challenge because most currently available fluorescent probes rely on the o-phenylenediamine (OPD) recognition site, which reacts with both NO and some abundant reactive carbonyl species (RCS) (such as dehydroascorbic acid and methylglyoxal) and some reactive oxygen/nitrogen species (ROS/RNS). To address this problem, a new fluorescent probe, NCNO, based on the N-nitrosation of aromatic secondary amine was designed to bypass the RCS, ROS, and RNS interference. As was expected, the probe NCNO could recognize NO with pronounced selectivity and sensitivity among ROS, RNS, and RCS. The probe was validated by detecting NO in live cells and deep tissues owing to its two-photon excitation and red-light emission. It was, hence, applied to monitor NO in ischemia reperfusion injury (IRI) in mice kidneys by two-photon microscopy for the first time, and the results vividly revealed the profile of NO generation in situ during the renal IRI process.
TL;DR: In this article, a non-AIE unit of triphenylamine, for the first time, is utilized to construct a bright ML luminogen of TPA-1BA.
Abstract: Mechanoluminescence (ML), a fantastic phenomenon, has attracted increasing attention. However, to date, enumerable bright ML luminogens have been reported based on AIE building blocks. Herein, a new non-AIE unit of triphenylamine, for the first time, is utilized to construct a bright ML luminogen of TPA-1BA. Regardless of the similar molecular structure of TPA-1BA and its analogues TPA-2BA and TPA-3BA, totally different mechanoluminescent activities were observed. Through the careful analyses of their crystal structures, it is found that the non-centrosymmetric molecular arrangement and high lattice stability under mechanical stimulation should be mainly responsible for the ML property of TPA-1BA.
TL;DR: In this article, organic polydopamine (PDA) nanoparticles were used to replace carbon nanotubes in liquid crystalline vitrimers for the construction of dynamic 3D structures.
Abstract: Achieving 3D structures that can be reversibly formed from dry 2D polymer films is useful for the development of suitable smart materials capable of converting an external stimulus into a mechanical response. For the construction of dynamic 3D structures, carbon nanotubes dispersed in liquid crystalline vitrimers constitute so far one of the few available materials that can show robust reconfiguration, easy repair, and low-temperature resistance. However, the severe aggregation of carbon nanotubes causes defects in the materials formed and incurs additional costs. Here, we show that organic polydopamine (PDA) nanoparticles can well replace carbon nanotubes to make suitable liquid crystalline vitrimers for the construction of dynamic 3D structures. We were able to disperse the PDA nanoparticles homogenously into the polymer matrix without carrying out any surface modification and without using any dispersant or sonication, which are required procedures for dispersing almost all inorganic nanoparticles into a polymer matrix. Moreover, the mechanical properties of the liquid crystalline vitrimer were found to be greatly improved. Using this composite, we also showed here a new method to achieve light-controlled 3D deformation into static structures.
TL;DR: In this article, a carbon-oxygen-bridged ladder-type donor unit (CO5) was invented and prepared via an intramolecular demethanolization cyclization approach.
Abstract: A carbon-oxygen-bridged ladder-type donor unit (CO5) was invented and prepared via an intramolecular demethanolization cyclization approach. Its single crystal structure indicates enhanced planarity compared with the carbon-bridged analogue indacenodithiophene (IDT). Owing to the stronger electron-donating capability of CO5 than IDT, CO5-based donor and acceptor materials show narrower bandgaps. A donor-acceptor (D-A) copolymer donor (PCO5TPD) and an A-D-A nonfullerene acceptor (CO5IC) demonstrated higher performance than IDT-based counterparts, PIDTTPD and IDTIC, respectively. The better performance of CO5-based materials results from their stronger light-harvesting capability and higher charge-carrier mobilities.