Latest ArticlesIn the work, we successfully explore a two-step hydrothermal method for scalable synthesis of the hybrid sodium titanate (NaTi8O13/NaTiO2) nanoribbons well in-situ formed on the multi-layered MXene Ti3C2 (designed as NTO/Ti3C2). Benefiting from the inherent structural and componential superiorities, the resulted NTO/Ti3C2 composite exhibits long-duration cycling stability and superior rate behaviors when evaluated as a hybrid anode for advanced SIBs, which delivers a reversible and stable capacity of ~82 mAh/g even after 1900 cycles at 2000 mA/g for SIBs.
The construction of highly stable and regular nanoreactors is a major challenge. In this work, we use a facile template protection method to obtain ZIF-67@SiO2 (JS) and to encapsulate metal oxide nanoparticles (Co3O4) into nanoreactors (SiO2). ZIF-67 crystals provide a cobalt species; SiO2 was first used as a protective layer of ZIF-67 and then as a nanoreactor for metastable metal oxide nanoparticles. On this basis, Co3O4@SiO2 with dodecahedron morphology were synthesized by calcining JS at different temperatures, followed by a hydrothermal reaction to obtain Co3(OH)4Si2O5. Subsequently, CoSx and CoPSiO2 were fabricated through sulfuration and phosphorization. The results in this work show that nanoreactors derived from metal-organic frameworks (MOFs) with a rational structure have broad development prospects.
In order to boost power conversion efficiency (PCE) and operation stability of organic solar cells (OSCs), we propose a new idea of phase junction materials (PJMs) used as a photoactive layer component to improve device performance and stability. For this purpose, a novel PJM of H-TRC8 based on rhodanine unit was designed with a conjugated AH-D-A framework. Here, AH is a hydrogen-donating electron acceptor unit, D-A is an electron donor-acceptor unit. It is found that H-TRC8 has a good carriertransporting ability, as well as definite hydrogen-bond and D-A interaction with donor/acceptor materials. While H-TRC8 is added into the PBDB-T/PC60BM blend film with 1.0 vol% DIO (1, 8-diiodooctane), the resulting blend film exhibited an enhanced absorption and improved morphology. The intermolecular hydrogen bond between H-TRC8 and PBDB-T plays an important role for them, which is confirmed via FT-IR spectra and 2D 1H NMR. As a result, the PBDB-T/PC60BM-based devices with 1.25 wt% H-TRC8 and 1.0 vol% DIO exhibit a significantly improved PCE of 8.06%, which is increased by 20.6% in comparison to that in the binary devices with 1.0 vol% DIO only (PCE = 6.68%). Furthermore, the device stability is significantly enhanced with only 43% PCE roll-off at 150 ℃ for 120 h. This work indicates that AH-D-A-type PJMs are promising photovoltaic materials used as photoactive-layer components to achieve high-performance fullerene OSCs with high device stability.
Spirohypatone A (1), a spirocyclic PPAP (polycyclic polyprenylated acylphloroglucinol) bearing an unprecedented hexahydro-1'H-spiro [cyclohexane-1, 2'-pentalene]-2, 4, 6-trione core and a new homologue (spirohypatone B, 2) were isolated from Hypericum patulum together with two known biosynthetic precursors. Compound 1 represents the first spirocyclic PPAP possessing a 5/5/6 carbon ring system, biogenetically derived from the intermediate 3 (attack from C-3 to C-12), which was differed from normal spirocyclic PPAPs (attack from C-3 to C-11). In addition, through extensive spectroscopic analysis, an interconversion mechanism of keto-enol of 1 was postulated and confirmed by its methylated reaction. The structures and absolute configurations of 1 and 2 were determined by comprehensive spectroscopic and chemical derivatized methods and X-ray crystallography. Compounds 1, 2, and 4 were tested to exhibit cytotoxic activities against several cancer cell lines.
NiS2 has become a research hotspot of anode materials for Na-ion batteries due to its high theoretical specific capacity. However, the volume effect, the dissolution of polysulfide intermediates and the low conductivity during the charge/discharge process lead to the low specific capacity and poor cycling stability. NiS2/rGO nanocomposite was prepared by a facile two-step process: GO was prepared by modified Hummers method, and then NiS2/rGO nanocomposite was synthesized by L-cys assisted hydrothermal method. NiS2/rGO nanocomposite shows excellent cycle performance and rate performance, which could be attributed to the mesoporous structure on the graphene skeleton with high conductivity. Besides, the chemical constraint of a unique S-O bond on NiS2 could inhibit the dissolution of intermediates and the loss of irreversible capacity.
Structural and functional biomimicking of the active site of [NiFe]-hydrogenases can provide helpful hints for designing bioinspired catalysts to replace the expensive noble metal catalysts for H2 generation and uptake. Treatment of dianion [Ni(phma)]2- [H4phma = N, N'-1, 2-phenylenebis(2-mercaptoacetamide)] with [NiCl2(dppp)] (dppp = bis(diphenylphosphino)propane) yielded a dinickel product [Ni(phma)(μ-S, S')Ni(dppp)] (1) as the model complex relevant to the active site of [NiFe]-H2ases. The structure of complex 1 has been characterized by single-crystal X-ray analysis. From cyclic voltammetry and controlled potential electrolysis studies, complex 1 was found to be a moderate electrocatalyst for the H2-evoluting reaction using ClCH2COOH as the proton source.
High-performance nanomaterial catalysts for hydrogen evolution reaction via electrochemical water splitting are significant to the development of hydrogen energy. In this work, we report a robust and highly active catalyst fabricated through direct electrochemical deposition of Pt nanodendrites at the surface of activated carbon (Pt NDs). Owing to the large electrochemically active area and the exposed (111) facet of Pt, Pt NDs exhibits outstanding activity towards hydrogen evolution reaction with a low requiring overpotential of 0.027 V at 10 mA/cm2 and Tafel slope of ≈ 22 mV/dec in acidic media. In addition, the hydrogen yield of Pt NDs is 30%-45% larger than that of commercial Pt/C at the same Pt loadings. Moreover, Pt NDs exhibits excellent long-term durability whose hydrogen production efficiency remains unchanged after six-hour hydrogen production, while the efficiency of commercial Pt/C catalyst decayed 9% under the same circumstance. Considering the superiority of catalytic activity and stability, this Pt NDs present great potentiality towards practical hydrogen production application.
In this article, three novel and simple molecular structure with donor-acceptor (D-A) type copolymers via only head-to-head alkoxy (OR) and/or alkylthio (SR) side chains onto the bithiophene (BT) as donor units and fluorinated benzotriazole (FBTA) as acceptor unit, namely, PBTOR-FBTA, PBTOSR-FBTA and PBTSRFBTA, were successfully designed and synthesized. The impacts of sulfur-oxygen (S⋯O) or sulfur-sulfur (S⋯S) noncovalent interactions on their physicochemical properties, molecular stacking, carrier mobility, morphologies of blend films, as well as their photovoltaic performance were deeply and systematically studied. The introduction of SR side-chains suddenly lowered the highest occupied molecular orbital (HOMO) energy levels, blue-shifted absorption, enhanced π-π stacking, as well as improved morphology of the photoactive layer blends in comparison with the reference polymer without SR side-chain. Polymer solar cells (PSCs) were fabricated to estimate their photovoltaic performance of the polymers. Under an optimized blend ratio of PBTSR-FBTA:PC71BM (1:0.8, w/w), the PBTSR-FBTAbased device exhibits a higher power conversion efficiency (PCE) of 6.25%, which is about 3.34 and 1.87 folds than that of the PBTOR-FBTA and PBTOSR-FBTA-based devices, respectively. Our research results demonstrate that the modification of the simple and low-cost SR side chains is an effective strategy to improve the photovoltaic performance of the polymers.
A colorimetric and fluorometric dual probe based on a water-soluble polythiophene derivative (PMTPBA) was designed and synthesized. It can be applied to determination of picric acid (PA) in 100% aqueous solution. The approach relies on the formation of supramolecular polythiophene assemblies in the presence of PA through electrostatic, charge transfer and π-π stacking interactions. This probe could be utilized for the rapid and visual detection of PA both in aqueous solution and solid support with high specificity and sensitivity. The detection limit of this sensor is as low as 5.0×10-8 mol/L.
Organic amines are important solvent and raw material in laboratory and industry, as well as releasing from cigarette smoke. It is significant to detect low-concentration amines for environment and public health. Here we reported that as-synthesized zinc oxide is an effective electrode material of electrochemical sensor for the detection of amines. The characterization results reveal that the ZnO morphologies experienced a change from hexagonal bowl-like microparticles, cones, prisms to nanoparticles by adjusting the reaction time, temperature, solvents and additives. Interestingly, ZnO material possessing hexagonal shapes and different sizes exhibits distinct electrochemical response in various amines solution, suggesting that there is a better dependent relationship between different morphological ZnO and amines detection. Particularly, regular hexagonal ZnO nanotablets exhibit a detectable electrochemical response and selectivity to ammonia, implying it can be serve as electrode material for highly effective detection of organic amines.
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