Latest ArticlesThe polysulfide shuttle limits the development of lithium-sulfur (Li-S) batteries with high energy density and long lifespan. Herein, nitrogen doped hollow carbon nanospheres (NHCS) derived from polymerization of dopamine on SiO2 nanospheres are employed to modify the commercial polypropylene/polyethylene/polypropylene tri-layer separators (PP/PE/PP@NHCS). The abundant nitrogen heteroatoms in NHCS exhibit strong chemical adsorption toward polysulfides, which can effectively suppress the lithium polysulfides shuttle and further enhance the utilization of active sulfur. Lithium-sulfur batteries employing the PP/PE/PP@NHCS deliver an initial discharge capacity of 1355 mAh/g and retain high capacity of 921 mAh/g after 100 cycles at 0.2 C. At a high rate of 2 C, the lithium-sulfur batteries exhibit capacity of 461 mAh/g after 1000 cycles with a capacity fading rate of 0.049% per cycle. This work demonstrates that the NHCS coated PP/PE/PP separator is promising for future commercial applications of lithium-sulfur batteries with improved electrochemical performances.
A novel air-stable n-type benzothiaphene endcapped azaarene (BTPQ) and its sulfonated derivative (BSPQ) were prepared via two pathways and characterized by NMR, UV–vis, fluorescence and cyclic voltammetry spectroscopy. Symmetrically introducing four nitrogen atoms into acenes, the semiconductor properties could be changed from p-type to n-type detected through the space charge limited current (SCLC) method. After sulfonation of BTPQ, BSPQ is with deeper frontier orbital energy levels and enhanced the electron mobility.
A series of DL-serine covalently modified multinuclear lanthanide implanted arsenotungstates K2[{Ln(H2O)7}2{As4W44O137(OH)18(H2O)2(DL-Ser)2}{Ln2(H2O)5(DL-Ser)}2]·65H2O (DL-Ser = DL-serine, Ln = La (1), Ce (2), Pr (3)) are obtained. Crystal structure analysis shows that these compounds are isomorphic and contain the basic [{As4W44O137(OH)18(H2O)2(DL-Ser)2}{Ln2(H2O)5(DL-Ser)}2]8– polyoxoanion constituted by two {As2W19O59(OH)8(H2O)}6‒ subunits, a [W6O23(OH)2(DL-Ser)2]14‒ fragment, and two embedded [Ln2(H2O)5(DL-Ser)]5+ groups, which further build into one dimensional linear chainlike structure via two peripheral Ln3+ ions. Most remarkably, these compounds exhibit rapid photochromic behaviors, which changed color quickly from white (1), yellow (2), green (3) to blue (1), brown (2) and glaucous (3) in ten minutes under UV irradiation, and that the colors gradually recovered in the dark for approximately 22 h.
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.
On-purpose propane dehydrogenation (PDH) has emerged as a profitable alternative to the traditional cracking of oil products for propylene production. By means of density functional theory (DFT) calculations, the present work demonstrates that Fe atoms may atomically disperse on MoS2 (Fe1/MoS2) and serve as a promising single-atom catalyst (SAC) for PDH. The catalytic activity of Fe1/MoS2 is attributed to the highly exposed d orbitals of single Fe atoms, while the propylene selectivity is originated from the kinetic inhibition of propylene dehydrogenation resulting from fast propenyl hydrogenation. The unique catalytic selectivity of Fe1/MoS2 may inspire further investigations of on-purpose dehydrogenations of propane on SACs.
Rhein (Rhe), an anthraquinone derivative, exhibits excellent anti-inflammatory effects and other pharmacological activities, but its clinical application remains limited due to poor solubility. The present work aims at the improvement of solubility and oral bioavailability of Rhe through cocrystal formation. For this purpose, Rhe and matrine (Mat) were selected as pharmaceutical ingredient (API) and cocrystal former (CCF), respectively, and the Rhe-Mat cocrystal was synthesized and characterized by single crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC). The formation mechanism of Rhe-Mat cocrystal was elucidated by molecular surface electrostatic potential (MSEP). It is worth mentioning that the 50-fold increment of dissolution in vitro was observed in pure water in the form of Rhe-Mat cocrystal. Furthermore, the in vivo studies revealed that Rhe-Mat cocrystal indicated the faster absorption rate and the higher peak blood concentration than the pure Rhe. Hence, it can be concluded that current study successfully improved the solubility and oral bioavailability of Rhe.
In this paper, Fe36Co44 nanocluster structure is used to catalyze the hydrolysis reaction of ammonia borane to produce H2. Firstly, we complete the construction of Fe36Co44 cluster structure and calculate the electronic properties of the cluster. By comparing the adsorption process of Ammonia Borane (AB) in active sites of the cluster, which have different Effective Coordination Number (ECN), the qualitative relationship between ECN and the catalytic activation of AB is clarified, and the optimal catalytic active site is obtained. Then, from the perspective of different reaction paths, we study the hydrolysis reaction of AB in multiple paths, and obtain 5 different reaction paths and energy profiles. The calculation results show that in the case of NH bond priority break (path 5), the reaction has the minimum rate-determining step (RDS) barrier (about 1.02 eV) and the entire reaction is exothermic (about 0.40 eV). So, path 5 is an optimal catalytic reaction path. This study will have an important guiding significance for the study of the AB hydrolysis reaction mechanism.
Artificial synapses with full synapse-like functionalities are of crucial importance for the implementation of neuromorphic computing and bioinspired intelligent systems. In particular, the development of artificial synapses with the capability to emulate multiplexed neural transmission is highly desirable, but remains challenging. In this work, we proposed a hybrid ambipolar synaptic transistor that combines two-dimensional (2D) molybdenum disulfide (MoS2) sheet and crystalline one-dimensional (1D) poly(3-hexylthiophene-2, 5-diyl) polymer nanowires (P3HT NWs) as dual excitatory channels. Essential synaptic functions, including excitatory postsynaptic current, paired-pulse facilitation, synaptic potentiation and depression, and dynamic filtering were emulated using the synaptic transistor. Benefitting from the dual excitatory channels of the synaptic transistor, the device achieved a fast switch between short-term and long-term memory by altering the charge carriers in the dual channels, i.e., electrons and holes. This emulated the multiplexed neural transmission of different excitatory neurotransmitters, e.g., dopamine and noradrenaline. The plasticity-switchable artificial synapse (PSAS) simulates the task-learning process of individuals under different motivations and the impact of success or failure on task learning and memory, which promises the potential to enable complex functionalities in future neuromorphic intelligent electronics.
The morphology and heterojunction engineering are effective ways to boost the performance of Cu-based catalysts. Herein, we have reported the designed synthesis of two-dimensional Cu-CuO heterojunction nanosheets (2D Cu-CuO NS) based on 3-aminopropyl-triethoxysilane (APTES, KH550) aided synthetic strategy. The APTES can act as both the ligand and alkali (-OH) source to guide the large-scale synthesis of 2D Cu-based precursor, which can transform into 2D Cu-CuO NS by the controllable post-treatment. The Si species from APTES can protect the particles from the severe aggregation and growth, guaranteeing the formation of 2D sheets composed of small-sized Cu-CuO heterojunction (about 20 nm). The heterojunction interfaces can provide plentiful active sites to boost the catalytic ability. The 2D sheets can provide large accessible surface, being conducive to the contact of the catalyst and reactants. Benefiting from above virtues, the 2D Cu-CuO NS showed the superior catalytic performance for the reduction of a series of nitro compounds, being superior to most reported non-noble metal-based catalysts. Notably, it exhibited good re-cycled performance with no obvious performance degradation after 10 consecutive catalysis. The present study will be promising to promote the application of the Cu-based catalysts, due to its ability to control the morphology and potential for the large-scale synthesis.
Acetylene (C2H2) and ethylene (C2H4) both are important chemical raw materials and energy fuel gasses. But the effective removement of trace C2H2 from C2H4 and the purification of C2H2 from carbon dioxide (CO2) are particularly challenging in the petrochemical industry. As a class of porous physical adsorbent, metal-organic frameworks (MOFs) have exhibited great success in separation and purification of light hydrocarbon gas. Herein, we rationally designed four novel MOFs by the strategy of pore space partition (PSP) via introducing triangular tri(pyridin-4-yl)-amine (TPA) into the 1D hexagonal channels of acs-type parent skeleton. By modulating the functional groups of linear dicarboxylate linkers for the parent skeleton, a series of isoreticular PSP-MOFs (SNNU-278−281) were successfully obtained. The synergistic effects of suitable pore size and Lewis basic functional groups make these MOFs ideal C2H2 adsorbents. The gas adsorption experimental results show that all MOFs have excellent C2H2 uptakes. Specially, SNNU-278 demonstrates a high C2H2 uptake of 149.7 cm3/g at 273 K and 1 atm. Meanwhile, SNNU-278−281 MOFs also show extremely great C2H2 separation from CO2 and C2H4. The optimized SNNU-281 with high-density hydroxy groups exhibits extraordinary C2H2/CO2 and C2H2/C2H4 dynamic breakthrough interval times up to 31 min/g and 17 min/g under 298 K and 1 bar.
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