Latest ArticlesThe effective design and synthesis of novel small-molecule donors (SMDs) is extremely essential for the in-depth study of the scientific problems of bulk heterojunction morphology and the improvement of photovoltaic performance in organic solar cells (OSCs). Importantly, developing a series of donors with different conjugated central donor (D) units is a remarkable strategy to obtain high-performance donors. Herein, two acceptor-donor-donor-acceptor (A-D-D-A) type oligomeric donors 2DTBDT and 2DTBDT-2T with two dithieno[2, 3-d: 2′, 3′-d']benzo[1, 2-b: 4, 5-b']dithiophene (DTBDT) as D units, without and with bithiophene as the π bridge respectively are designed and synthesized successfully. The central linked-DTBDT unit can provide a larger conjugated plane and promote π electron delocalization, which can effectively improve π-π interactions between donors and regulate the crystallinity. And we found that the π bridge provided 2DTBDT-2T with 12.31% efficiency that is already a high efficiency in OSCs, whereas 2DTBDT with merely 3.63% efficiency, both with 2, 2′-((2Z, 2′Z)-((12, 13-bis(2-ethylhexyl)-3, 9-diundecyl-12, 13-dihydro-[1,2,5]thiadiazolo[3, 4-e]thieno[2, "3′': 4′, 5′]thieno[2′, 3′: 4, 5]pyrrolo[3, 2-g]thieno[2′, 3′: 4, 5]thieno[3, 2-b]indole, 10-diyl)bis(methanylylidene))bis(5, 6-difluoro-3-oxo-2, 3-dihydro-1H-indene-2, 1-diylidene)) dimalononitrile (Y6) as the acceptor. We conjecture that the main reason for the different device performance may be ascribed to the different molecular stacking orientation of the oligomeric donors and morphology features of the donors: Y6 blend films. Compared to the predominant face-on orientation of the 2DTBDT neat film, the 2DTBDT-2T neat film performed a preferential edge-on orientation, which obtained a smoother surface, stronger crystallinity and more uniform phase separation in the 2DTBDT-2T: Y6 blend films with nanofiber structure, which delivered higher and more balanced carrier mobilities, the more efficient exciton dissociation and reduced biomolecule recombination, therefore obtaining better power conversion efficiencies (PCEs). We speculate that the transformation of molecular stacking orientation of oligomeric donors is possibly due to that π bridge extended and twisted the molecular structure of 2DTDBT-2T, resulting in an edge-on orientation relative to the substrate. These findings demonstrate that the single-bond-linked donor strategy is an alternative method to design the donors towards high-performance OSCs.
Photocatalytic hydrogen evolution from water splitting is a promising strategy for realizing the vision of carbon neutrality. Herein, a novel SrTiO3-SrCO3 n-n heterojunction was used for the first time for water splitting to generate H2. The heterojunction was synthesized by a soft chemical one-pot hydrothermal method. The SrTiO3-SrCO3 loading with 3 wt% Pt shows the maximum photocatalytic H2 evolution rate of 3.62 mmol h−1g−1 under simulated sunlight irradiation, which is 20.1 times higher than that of pristine SrTiO3. The apparent quantum efficiency of SrTiO3-SrCO3 reaches 21.73% at 313 nm, and it shows good stability during cyclic experiment. The formation of compact SrTiO3-SrCO3 heterojunction with strong interfacial electronic interaction promotes the transmission and separation of photo-generated carriers. The results of XPS, PL, PC, EIS and DFT support the mechanism of improving photocatalytic activity based on carrier dynamics. This work provides a facile and effective method to enhance the activity of SrTiO3-based heterojunction photocatalysts.
Pyrogenic carbonaceous matter (PCM) catalyzes azo dye decolorization by sulfide, but the nitrogen doping catalytic mechanisms are poorly understood. In this study, we found that stagnate time of azo dye methyl orange (MO) decolorization was reduced to 0.54-18.28 min in the presence of various nitrogen-doped graphenes (NGs), remarkably lower compared to graphene itself. Particularly, graphitic nitrogen played a critical role in NGs-catalyzed MO decolorization by sulfide. Gas chromatography-mass spectrometry and in-situ surface Raman analysis demonstrated that doping nitrogen, especially graphite one facilitated reactive intermediate polysulfides formation. This is attributed to the improved electron conductivity through graphitic nitrogen doping, and the enhanced interactions between sulfide and carbon atoms bonded to graphitic nitrogen. This study not only provides a better understanding of PCM impact on transformations and fates of organic pollutants in natural environments, but also offer a new regulation strategy for more efficient wastewater treatment processes in PCM-catalyzed engineering systems.
Graphene oxide (GO) with unique characteristics grasps striking potentials in both academic and industrial applications. After being released into natural waters, the dispersity and stability of GO might be altered by the chemical conditions in the receiving water bodies. In this review, we summarized that the aggregation of GO in aquatic environments is mostly dependent on properties of nanoparticles (size, structure, and functional groups) and complex water chemistry (pH, temperature, light, ionic strength, and dissolved organic matter). The knowledge about the aggregation/stability of GO is still insufficient due to the variations in GO properties and complex system of natural waters. Although studies about environmental transformation of graphene-related materials can be accessed but a systematic study taking into consideration the various factors of GO and aquatic systems responsible for aggregation of GO is still lacking. Therefore, we summarized that GO homoaggregation or heteroaggregation with other solid particles can affect the distribution in different depths of rivers and toxicity toward plankton or benthic organisms. More studies are needed to investigate the stability of GO in the long term, the effect of other nanomaterial on GO aggregation, the alteration of water constituents at different regions/time and its effect on GO aggregation, to understand the transportation and impact of GO in the environment.
Through uncomplicated carbonation process, a carbon-embedded CoNiSe2/C nanosphere was synthesized from Ni-Co-MOF (metal-organic framework) precursor whose controllable structure and synergistic effect of bimetallic Ni/Co brought CoNiSe2/C anodes with high specific surface area (172.79 m2/g) and outstanding electrochemical performance. CoNiSe2/C anodes obtained reversible discharge capacities of 850.9 mAh/g at 0.1 A/g after cycling for 100 cycles. In addition, CoNiSe2/C exhibits excellent cycle stability and reversibility in the rate test at a current density of 0.1–2.0 A/g. When the current density returns to 0.5 A/g for 150 cycles, its discharge ratio the capacity is 330.8 mAh/g. Electrochemical impedance spectroscopy (EIS) tests suggested that CoNiSe2/C anodes had a lower charge transfer impedance of 130.02 Ω after 30 cycles. In-situ X-ray diffraction (XRD) tests confirmed the alloying mechanism of CoNiSe2/C which realized higher lithium storage capacity. This work affords substantial evidence for the extension of bimetallic selenides in secondary batteries, promoting the development of bimetallic selenides in anode materials for LIBs.
Prion diseases are fatal neurodegenerative diseases that can cause severe dementia. The misfolding and accumulation of the prion peptide (PrP)106–126 is crucial, and this process is closely relevant to biological membranes. However, how PrP106–126 aggregation is affected by the molecular chirality of phospholipid membrane is unknown. Thus, in this study, a pair of L- and D-aspartic acid (Asp)-modified 1, 2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) were synthesized to construct chiral liposomes. We discover that L-Asp-DPPE liposomes strongly inhibit the oligomerization and amyloidogenesis of PrP106–126, whether acting on monomers or oligomers, which rescues cytotoxicity induced by PrP106–126. By comparison, D-Asp-DPPE liposomes inhibit peptide oligomerization only at a high concentration and cannot prevent amyloidogenesis when acting on oligomers, which lead to pronounced cytotoxicity. Apoptosis experiment, dynamic change of intracellular Ca2+ (iCa2+) and Ca2+ release from endoplasmic reticulum (ER), reactive oxygen species (ROS) production, adsorption dynamics and affinity tests, and fluorescent imaging clearly disclose that molecular chirality of the liposomes dominates conformational transition of PrP106–126 from random coil to β-sheet, binding and adsorption of the monomers and oligomers, and subsequent fibrillation process, resulting in distinct inhibition effect in Ca2+ overload and release, ROS production and cell apoptosis. This work is the first to report that interfacial molecular chirality is a potentially crucial influence on the fibrillation process of PrP106–126 and its cell responses, whereas the convergence of chiral amino acids and liposomes can be considered potential inhibitors in prion diseases.
Metal-organic framework nanosheets (MOF NNs) offer potential opportunities for many applications, but an efficient strategy for the scalable preparation of few-layered two-dimensional (2D) MOF NNs are still a major challenge. Herein, we present an efficient top-down method for the synthesis of the Ni-BDC (Ni2(OH)2(1, 4-BDC); 1, 4-BDC = 1, 4-benzenedicarboxylate) nanosheets utilizing a novel thermal expansion-quench method of the flowerlike bulky MOFs in liquid N2. The obtained Ni-BDC nanosheets exhibit significantly enhanced photocatalytic performance of reductive CO2 deoxygenation (7.0 µmol h−1 mg−1) under visible light illumination compared with the bulky MOFs, due to much higher surface area for CO2 adsorption, more abundant active sites exposed and stronger electron transport ability of the nanosheets. More importantly, this synthetic strategy can be extended to fabricate other MOF nanosheets which also exhibit significantly improved performance for deoxygenative CO2 reduction compared to their bulky counterparts. This work may provide a guideline for preparing other 2D layered photocatalysts materials to realize energy conversion applications.
Intracellular pH undertakes critical functions in various biological and pathological processes. It is important to monitor intracellular pH fluctuations for understanding physiological and pathological processes. Here, one aldehyde-bearing cyclometalated iridium(Ⅲ) complex ([(4-pba)2Ir(dcphen)]PF6, 4-pba = 4-(2-pyridyl) benzaldehyde, dcphen = 4, 7-dichloro-1, 10-phenanthroline, probe 1) was synthesized and used to track intracellular pH fluctuations. Probe 1 displayed pH-dependent luminescence property in pH range of 1.81–6.81 with an evaluated pKa value of 4.30 in BR buffer-DMSO (v:v = 99:1). An intramolecular hydrogen bonds assisted pH-responsive mechanism was proposed for the pH-responsive behavior of probe 1. Probe 1 was successfully applied for imaging and tracking pH fluctuations in HeLa cells under external stimulation with fast response time, good photostability as well as low cytotoxicity and high cell permeability. This work demonstrates that aldehyde-bearing cyclometalated iridium(Ⅲ) complex can be used as alternative pH-responsive probe for real-time tracking intracellular pH fluctuations, which provides a strategy for the design of pH-responsive probe in versatile applications.
Constructing anodes with fast ions/electrons transfer paths is an effective strategy to achieve high-performance sodium ion batteries (SIBs)/potassium ion batteries (PIBs). Amorphous carbon is a promising candidate anode for SIBs/PIBs owing to its disordered carbon layers, abundant defects/pores, and low-cost resources. However, the larger radius of Na+/K+ leading to depressed kinetics and poor cycling performance, impeding their further applications. Herein, we propose an efficient strategy to construct of nitrogen, sulfur co-doped hollow carbon nanospheres (NS-HCS) involving an in situ growth of polydopamine on nano-Ni(OH)2 template with subsequent sulfur doping process. During the formation process, the produced Ni nanospheres play as the hard template and catalyst for the formation of hollow carbon nanosphere with partially graphite microcrystalline structure, while the sulfur doping process can enlarge the interlayer space and create more defects on the surface of carbon nanospheres, thus synchronous improve the Na+/K+ insertion and adsorption ability in NS-HCS. With the synergistic control of the enlarged interlayer spacing, high content of pyridinic N/pyrrolic N and graphitization, a hybrid storage mechanism facilitates the transport kinetics and endows the NS-HCS electrode with high capacities and good cycling stability in SIBs and PIB. Benefit from the multiple effects, NS-HCS exhibits the improved capacity of 274.8 mAh/g at 0.1 A/g and excellent cycling stability of 149.5 mAh/g after 5000 cycles at 2.5A/g in SIBs, as well as good potassium ion storage behavior with a high capacity retention of 76.5% after 700 cycles at 1.0 A/g, demonstrating the potential applications of NS-HCS for high-performance SIBs and PIBs
Previous studies demonstrated that three-dimensional (3D) multicellular tumor spheroids (MCTS) could more closely mimic solid tumors than two-dimensional (2D) cancer cells in terms of the spatial structure, extracellular matrix-cell interaction, and gene expression pattern. However, no study has been reported on the differences in lipid metabolism and distribution among 2D cancer cells, MCTS, and solid tumors. Here, we used HepG2 liver cancer cell lines to establish these three cancer models. The variations of lipid profiles and spatial distribution among them were explored by using mass spectrometry-based lipidomics and matrix-assisted laser desorption/ionization mass spectrometry imaging (MSI). The results revealed that MCTS, relative to 2D cells, had more shared lipid species with solid tumors. Furthermore, MCTS contained more comparable characteristics than 2D cells to solid tumors with respect to the relative abundance of most lipid classes and mass spectra patterns. MSI data showed that 46 of 71 lipids had similar spatial distribution between solid tumors and MCTS, while lipids in 2D cells had no specific spatial distribution. Interestingly, most of detected lipid species in sphingolipids and glycerolipids preferred locating in the necrotic region to the proliferative region of solid tumors and MCTS. Taken together, our study provides the evidence of lipid metabolism and distribution demonstrating that MCTS are a more suitable in vitro model to mimic solid tumors, which may offer insights into tumor metabolism and microenvironment.
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