Latest ArticlesMetal-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.
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.
Developing bifunctional electrocatalysts for overall water splitting reaction is still highly desired but with large challenges. Herein, an amorphous FeCoNi-S electrocatalyst was developed using thioacetamide for the sulfuration of FeCoNi hydroxide during the hydrothermal process. The obtained catalyst exhibited an amorphous structure with hybrid bonds of metal-S bond and metal-O bonds in the catalyst system. The optimized catalyst showed a largely improved bifunctional catalytic ability to drive water splitting reaction in the alkaline electrolyte compared to the FeCoNi hydroxide. It required an overpotential of 280 mV and 80 mV (No-IR correction) to offer 10 mA/cm2 for water oxidation and reduction respectively; a low cell voltage of 1.55 V was required to reach 10 mA/cm2 for the water electrolysis with good stability for 12 h. Moreover, this catalyst system showed high catalytic stability, catalytic kinetics, and Faraday efficiency for water splitting reactions. Considering the very low intrinsic activity of FeCoNi hydroxide, the efficient bifunctional catalytic ability should result from the newly formed hybrid active sites of metallic metal-S species and the high valence state of metal oxide species. This work is effective in the bifunctional catalytic ability boosting for the transition metal materials by facile sulfuration in the hydrothermal approach.
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.
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.
Lithium-oxygen (Li-O2) batteries are considered as the next generation for energy storages systems due to the higher theoretical energy density than that of Li-ion batteries. However, the high charge overpotential caused by the insulated Li2O2 results in low energy efficiency, side reaction from electrolyte and cathode, and therefore poor battery performance. Designing noble metal-based catalysts can be an effective strategy to develop high-performance Li-O2 batteries with low charge overpotentials and outstanding cycle stability. However, the charge mechanism for noble metal-based catalysts is not clear and even contradictory. Herein, several charge mechanisms of Li2O2 are first discussed. Subsequently, the possible charge processes of Li-O2 batteries with noble metal-based catalysts are illustrated. In addition, the future development for noble metal-based catalysts is outlined.
Sperm damage caused by reactive oxygen species (ROS) is one of the main causes of male infertility. Therefore, the level of ROS in sperm is an important indicator for the diagnosis and prognosis of male infertility. Herein, we constructed a single sperm ROS detection method (SSRDM) with an optical micro-probe fabricated via focused ion beam process. The micro-probe is used to separately excite fluorescence in the sperm and the area around the sperm after ROS staining, and the difference in fluorescence values can reflect the level of ROS in the sperm. We collected 102 semen samples and 72 of them were divided into asthenozoospermia and non-asthenozoospermia groups. SSRDM and flow cytometry were used to detect the ROS levels of the two groups. The results of SSRDM showed that the ROS levels of asthenozoospermia group were higher than that of non-asthenozoospermia group (P = 0.002), while the results of flow cytometry indicated no difference (P = 0.152). In terms of ROS levels, compared with flow cytometry, SSRDM has a stronger ability to distinguish between those two groups, providing a reliable basis for assessment of sperm quality. Another 30 semen samples were used to investigate temperature and temporal variability of SSRDM to ensure the stability and accuracy of this method. Overall, we have developed a method that can quantitatively detect fluorescent substances in sperm at the single-cell level supplying evidence for diagnosis and prognosis of male infertility.
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
Lithium dendrite growth due to uneven electrodeposition usually leads to the potential hazard of internal short circuit and shorter lifetime of lithium-based batteries. Extensive efforts have been devoted to explore the effects of single or two factors on dendrite growth, involving the diffusion coefficient, exchange current density, electrolyte concentration, temperature, and applied voltage. However, these factors interrelate during battery operation, signifying that a understanding of how they jointly influence the electrodeposition is of paramount importance for the effective suppression of dendrites. Here, we incorporate the dependent relationships among key factors into the phase-field model to capture their synergistic effects on electrodeposition. All the simulations are implemented in our self-written MATLAB code under a unified modeling framework. Following this, five groups of experimentally common dendrite patterns are reproduced and the corresponding electrodeposition driving forces are identified. Unexpectedly, we find that with the decrease of the ratio of exchange current density (or applied voltage) to diffusion coefficient, the electrodeposition morphology changes from needle-like dendrites to columnar dendrites and to uniform deposition. The present phase-field simulation tends to depict the practical electrodeposition process, providing important insights into synergistic regulation to suppress dendrite growth.
Lanthanide metal-organic frameworks (Ln-MOFs), which is composed of organic bridging ligands and Ln3+ ions/clusters, is an important component of luminescent MOFs. Compared with transition metal ions, lanthanide ions have a higher coordination number and abundant coordination geometry. Moreover, Ln-MOFs have special characteristics such as good porosity, topological diversity, high surface area and highly adjustable structure. The energy transfer (ET) process in Ln-MOFs could be easily affected by the interaction between host framework and guest, resulting in the change of luminescence intensity or color. Over the past few decades, the features of Ln-MOFs open the door to a range of incredibly important applications. However, there are few reviews on systemic summary of the various applications of Ln-MOFs. In this paper, we summarized the latest progress of Ln-MOFs applications, including the Ln-MOFs in chemical and biological sensors, optical information devices and catalysis, respectively, and discussed design mechanism. The possible problems in current research are briefly prospected, hoping to provide some helpful guidance for the future development of Ln-MOF materials.
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