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1.
Jinying Wei Daping Qiu Min Li Zhenyu Xie Ang Gao Hongru Liu Suhong Yin Dongsheng Yang Ru Yang 《RSC advances》2019,9(18):10237
Ion substitution and micromorphology control are two efficient strategies to ameliorate the electrochemical performance of supercapacitors electrode materials. Here, Al3+ doped α-Ni(OH)2 with peony-like morphology and porous structure has been successfully synthesized through a facile one-pot hydrothermal process. The Al3+ doped α-Ni(OH)2 electrode shows an ultrahigh specific capacitance of 1750 F g−1 at 1 A g−1, and an outstanding electrochemical stability of 72% after running 2000 cycles. In addition, the Al3+ doped α-Ni(OH)2 electrode demonstrates an excellent rate capability (92% retention at 10 A g−1). Furthermore, by using this unique Al3+ doped α-Ni(OH)2 as the positive electrode and a hierarchical porous carbon (HPC) as the negative electrode, the assembled asymmetric supercapacitor can demonstrate a high energy/power density (49.6 W h kg−1 and 14 kW kg−1). This work proves that synthesizing an Al3+ doped structure is an effective means to improve the electrochemical properties of α-Ni(OH)2. This scheme could be extended to other transition metal hydroxides to enhance their electrochemical performance.Ion substitution and micromorphology control are two efficient strategies to ameliorate the electrochemical performance of supercapacitors electrode materials. 相似文献
2.
Kaoru Uegaki Kazuhiro Nakabayashi Shin-ichi Yamamoto Toshio Koizumi Shotaro Hayashi 《RSC advances》2020,10(32):19034
Donor–acceptor π-conjugated random copolymers based on regioregular poly(3-hexylthiophene), rr-P3HT, with unsymmetrical monothienoisoindigo moieties were obtained by direct arylation polycondensation of 2-bromo-3-hexylthiophene with unsymmetrical monothienoisoindigo motifs under the optimized conditions [palladium-immobilized on thiol-modified silica gel with chloride counter anions, PITS-Cl (2.5 mol%), PivOH (1.0 equiv.), K2CO3 (3.0 equiv.), DMAc, 100 °C, 24 h]. Incorporation of unsymmetrical monothienoisoindigo electron-acceptor units into the polymers tuned their highest occupied and lowest unoccupied molecular orbital levels, which were close to those of the hole transport material (PEDOT) and electron transport material (PCBM), respectively, in thin-film organic solar cells. Alkyl chains of the unsymmetrical monothienoisoindigo units in the polymers tuned their macrostructural order, resulting in the observation of crystalline patterns and specific absorption peaks in thin films. An organic solar cell containing the most crystalline random copolymer showed an efficiency of 1.91%.Donor–acceptor π-conjugated random copolymers based on regioregular poly(3-hexylthiophene) with unsymmetrical monothienoisoindigo moieties were obtained by direct arylation polycondensation. 相似文献
3.
Aldona Bal
inait Kush K. Upadhyay Kristina Radinovi Diogo M. F. Santos M. F. Montemor Biljana ljuki 《RSC advances》2022,12(16):10020
β-Ni(OH)2 nanoplatelets are prepared by a hydrothermal procedure and characterized by scanning and transmission electron microscopy, X-ray diffraction analysis, Raman spectroscopy, and X-ray photoelectron spectroscopy. The material is demonstrated to be an efficient electrocatalyst for oxygen reduction, oxygen evolution, and hydrogen evolution reactions in alkaline media. β-Ni(OH)2 shows an overpotential of 498 mV to reach 10 mA cm−2 towards oxygen evolution, with a Tafel slope of 149 mV dec−1 (decreasing to 99 mV dec−1 at 75 °C), along with superior stability as evidenced by chronoamperometric measurements. Similarly, a low overpotential of −333 mV to reach 10 mA cm−2 (decreasing to only −65 mV at 75 °C) toward hydrogen evolution with a Tafel slope of −230 mV dec−1 is observed. Finally, β-Ni(OH)2 exhibits a noteworthy performance for the ORR, as evidenced by a low Tafel slope of −78 mV dec−1 and a number of exchanged electrons of 4.01 (indicating direct 4e−-oxygen reduction), whereas there are only a few previous reports on modest ORR activity of pure Ni(OH)2.β-Ni(OH)2 nanoplatelets produced via a hydrothermal method exhibit good performance as trifunctional electrocatalysts for the ORR, OER, and HER in alkaline media along with excellent stability under cathodic/anodic polarisation conditions. 相似文献
4.
Shan Sun Peng Diao Cuiyun Feng Eleonora-Mihaela Ungureanu Yi Tang Bin Hu Qing Hu 《RSC advances》2018,8(35):19776
Electrochemical oxidative degradation (EOD) is a particularly promising technique for removing organic pollutants from wastewater. However, due to the high overpotential of EOD in conventional anode materials, the energy cost of EOD is usually very high, which greatly promotes the search for highly active, stable, and energy-efficient anodic catalysts. Herein, we demonstrated that nickel-foam-supported (NF-supported) β-Ni(OH)2 (NF/β-Ni(OH)2) prepared via a facile hydrothermal method could be used as an energy efficient anode for EOD. The as-prepared 3D porous NF/β-Ni(OH)2 exhibited high activity toward the electrochemical oxidation of methyl orange (MO) in the low potential region (<1.07 V vs. SCE). This property differs greatly from those of the conventional anode materials that require a high positive potential to keep them active for EOD, making NF/β-Ni(OH)2 an energy-efficient and active anode material for EOD. With an oxidation current density of 0.25 mA cm−2, the decolorization of MO was completed within 30 min, and the COD removal after 3h of reaction was 63.0%. The normalized energy consumption for the 3 h degradation of MO was 22.2 kW h (kg COD)−1, which is only a fraction of (or even one tenth of) the values reported in the literature. Moreover, NF/β-Ni(OH)2 had a good stability and recyclability for EOD. No activity decay was observed during 10 h of EOD and the COD removal remained almost unchanged after four consecutive reaction cycles. We demonstrated experimentally that the NF/β-Ni(OH)2 anode could generate large amounts of hydroxyl radicals and that the oxidation of MO by hydroxyl radicals was the main mechanism during EOD. We believe that this work opens a new avenue for developing highly active and energy-efficient anode materials that can work in the low potential region for EOD.A novel NF/β-Ni(OH)2 catalyst for energy efficient electrochemical degradation of methyl orange was fabricated via a facile hydrothermal method. 相似文献
5.
We investigated the addition of alkali metal elements (namely Na+, K+, Rb+, and Cs+) to Cu-modified CH3NH3PbI3−δClδ photovoltaic devices and their effects on the photovoltaic properties and electronic structure. The open-circuit voltage was increased by CuBr2 addition to the CH3NH3PbI3−δClδ precursor solution. The series resistance was decreased by simultaneous addition of CuBr2 and RbI, which increased the external quantum efficiencies in the range of 300–500 nm, and the short-circuit current density. The energy gap of the perovskite crystal increased through CuBr2 addition, which we also confirmed by first-principles calculations. Charge carrier generation was observed in the range of 300–500 nm as an increase of the external quantum efficiency, owing to the partial density of states contributed by alkali metal elements. Calculations suggested that the Gibbs energies were decreased by incorporation of alkali metal elements into the perovskite crystals. The conversion efficiency was maintained for 7 weeks for devices with added CuBr2 and RbI.Addition of alkali metal elements (Na+, K+, Rb+, and Cs+) to Cu-modified CH3NH3PbI3−δClδ devices improved the photovoltaic properties. 相似文献
6.
Md. Tuhinur R. Joy Nikhil C. Bhoumik Shishir Ghosh Michael G. Richmond Shariff E. Kabir 《RSC advances》2020,10(73):44699
The triosmium cluster [Os3(CO)10(μ-OH)(μ-H)] containing bridging hydride and hydroxyl groups at a common Os–Os edge was obtained in good yield (ca. 75%) from the hydrolysis of the labile triosmium cluster [Os3(CO)10(NCMe)2] in THF at 67 °C. [Os3(CO)10(μ-OH)(μ-H)] reacts with dppm at 68 °C to afford the isomeric clusters 1 and 2 with the general formula [Os3(CO)8(μ-OH)(μ-H)(μ-dppm)] that differ by the disposition of bridging dppm ligand. Cluster 1 is produced exclusively from the reaction of [Os3(CO)10(μ-OH)(μ-H)] with dppm in CH2Cl2 at room temperature in the presence of added Me3NO. Heating cluster 1 at 81 °C furnishes 2 in a process that likely proceeds by the release of one arm of the dppm ligand, followed by ligand reorganization about the cluster polyhedron and ring closure of the pendent dppm ligand. The oxo-capped [Os3(CO)7(μ3-CO)(μ3-O)(μ-dppm)] (3) has been isolated starting from the thermolysis of either 1 or 2 at 139 °C. Reactions of [Os3(CO)10(μ-dppm)] with ROH (R = Me, Et) in the presence of Me3NO at 80 °C furnish [Os3(CO)8(μ-OH)(μ,η1,κ1-OCOR)(μ-dppm)] (4, R = Me; 5, R = Et). Clusters 1–5 have been characterized by a combination of analytical and spectroscopic studies, and the molecular structure of each product has been established by X-ray crystallography. The bonding in these products has been examined by electronic structure calculations, and cluster 1 is confirmed as the kinetic product of substitution, while cluster 2 represents the thermodynamically favored isomer.The cluster [Os3(CO)10(μ-OH)(μ-H)] was obtained in 75% from the hydrolysis of [Os3(CO)10(NCMe)2]. 相似文献
7.
The low utilization rate of active materials has been a critical obstacle for the industrialization of ultracapacitors. In this study, a thin layer of cross-structured ultrathin α-Ni(OH)2 nanosheets was successfully grown in situ on the surface of a nickel foam as a high-conductivity framework by a vibratory water bath route under a low temperature (80 °C) and mild conditions. Combining the ultrathin α-Ni(OH)2 nanosheets and ultrashort electron transport, the strategy of a perfect intercalation structure of α-Ni(OH)2 and a thin layer of active material on a continuous conductive framework resulted in a high utilization rate of active material, which further achieved high specific capacitance of 213.55 F g−1 at 1 A g−1 in a two-electrode system and high capacitance retention from three to two electrode system (753.79 F g−1 at 1 A g−1 in the three-electrode system). Meanwhile, the device also achieved high energy density of 74.94 W h kg−1 at power density of 197.4 W kg−1 and still retained 24.87 W h kg−1 at power density of 3642 W kg−1.The low utilization rate of active materials has been a critical obstacle for the industrialization of ultracapacitors. 相似文献
8.
In(OTf)3-catalyzed intramolecular hydroarylation of α-phenylallyl β-ketosulfones provides sulfonyl 1-benzosuberones and 1-tetralones in moderate to good yields in refluxing (CH2Cl)2 under open-vessel and easy-operation reaction conditions. A plausible mechanism is proposed and discussed. This highly regioselective protocol provides an atom-economic ring-closure route.In(OTf)3-catalyzed intramolecular hydroarylation of α-phenylallyl β-ketosulfones provides sulfonyl 1-benzosuberones and 1-tetralones in moderate to good yields in refluxing (CH2Cl)2 under open-vessel and easy-operation reaction conditions. 相似文献
9.
Development of γG, γA, γM, β1C/β1A, C′1 esterase inhibitor, ceruloplasmin, transferrin, hemopexin, haptoglobin, fibrinogen, plasminogen, α1-antitrypsin, orosomucoid, β-lipoprotein, α2-macroglobulin, and prealbumin in the human conceptus
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The synthesis of γG, γA, γM, β1C/β1A, C′1 esterase inhibitor, ceruloplasmin, transferrin, hemopexin, haptoglobin, fibrinogen, α1-antitrypsin, orosomucoid, β-lipoprotein, α2-macroglobulin, and prealbumin was studied in 15 normal human embryos and fetuses of 29 days to 18 wk gestation and in the yolk sacs of four embryos from 5.5 to 11.5 wk gestation using tissue culture in 14C-labeled amino acids followed by radioimmunoelectrophoresis. The human embryo as early as 29 day gestation synthesized β1C/β1A, C′1 esterase inhibitor, transferrin, hemopexin, α1-antitrypsin, β-lipoprotein, α2-macroglobulin, and prealbumin in culture. At 32 days gestation ceruloplasmin and orosomucoid were also synthesized, but synthesis of fibrinogen was not observed before 5.5 wk. Synthesis of γM occurred as early as 10.5 wk gestation, and γG synthesis was found in cultures as early as 12 wk gestation; γA synthesis was not detected in any of the tissue cultures. With the exception of the γ-globulins, each of the proteins studied was synthesized by the liver, but additional sites of synthesis for some of these proteins were also found. Synthesis of γG and γM occurred primarily in the spleen, but other sites of synthesis were noted as well. 相似文献
10.
Sheng Zhang Wenjiao Mo Jiangwei Zhang Haipeng Wu Min Li Xingqiang Lü Bing Yin Desuo Yang 《RSC advances》2018,8(52):29513
Two Dy(iii) single-ion magnets, formulated as [Dy(Phen)(Cl-tcpb)3] (Cl-1) and [Dy(Phen)(CH3O-tmpd)3] (CH3O-2) were obtained through β-diketonate ligands (Cl-tcpb = 1-(4-chlorophenyl)-4,4,4-trifluoro-1,3-butanedione and CH3O-tmpd = 4,4,4-trifluoro-1-(4-methoxyphenyl)-1,3-butanedione) with different substituent groups (–Cl/–OCH3) and auxiliary ligand, 1,10-phenanthroline (Phen). The Dy(iii) ions in Cl-1 and CH3O-2 are eight-coordinate, with an approximately square antiprismatic (SAP, D4d) and trigonal dodecahedron (D2d) N2O6 coordination environment, respectively, in the first coordination sphere. Under zero direct-current (dc) field, magnetic investigations demonstrate that both Cl-1 and CH3O-2 display dynamic magnetic relaxation of single-molecule magnet (SMM) behavior with different effective barriers (Ueff) of 105.4 cm−1 (151.1 K) for Cl-1 and 132.5 cm−1 (190.7 K) for CH3O-2, respectively. As noted, compound CH3O-2 possesses a higher effective barrier than Cl-1. From ab initio calculations, the energies of the first excited state (KD1) are indeed close to the experimental Ueff as 126.7 cm−1vs. 105.4 cm−1 for Cl-1 and 152.8 cm−1vs. 132.5 cm−1 for CH3O-2. The order of the calculated energies of KD1 is same as that of the experimental Ueff. The superior SIM properties of CH3O-2 could have originated from the larger axial electrostatic potential (ESP(ax)) felt by the central Dy(iii) ion when compared with Cl-1. The larger ESP(ax) of CH3O-2 arises from synergic effects of the more negative charge and shorter Dy–O distances of the axial O atoms of the first sphere. These charges and distances could be influenced by functional groups outside the first sphere, e.g., –Cl and –OCH3.Further studies from the viewpoint of electrostatic potential demonstrate that the larger axial electrostatic potential (ESP) felt by the central Dy (iii) ion of CH3O-2 is responsible for its better SIM property when compared with Cl-1. 相似文献
11.
To understand the dynamics of the cation in layered perovskite-type (CH3CH2NH3)2CuCl4, the temperature-dependent chemical shifts and spin–lattice relaxation times T1ρ in the rotating frame have been measured using 1H magic angle spinning nuclear magnetic resonance (MAS NMR) and 13C cross-polarization (CP)/MAS NMR techniques. Each proton and carbon in the (CH3CH2NH3)+ cation is distinguished in MAS NMR spectra. The Bloembergen–Purcell–Pound (BPP) curves for 1H T1ρ in CH3CH2 and NH3, and for the 13C T1ρ in CH3 and CH2 are revealed to have minima at low temperatures. This implies that the curves represent the CH3 and NH3+ rotational motions. The amplitude of the cationic motion is enhanced at the C-end, that is, the N-end of the organic cation is fixed to the inorganic layer through N–H⋯Cl hydrogen bonds, and T1ρ becomes short with larger-amplitude molecular motions.To understand the dynamics of the cation in layered perovskite-type (CH3CH2NH3)2CuCl4, the temperature-dependent chemical shifts and spin–lattice relaxation times T1ρ have been measured using 1H MAS NMR and 13C CP/MAS NMR techniques. 相似文献
12.
Shahin A. Begum Md. Arshad H. Chowdhury Shishir Ghosh Derek A. Tocher Michael G. Richmond Li Yang K. I. Hardcastle Edward Rosenberg Shariff E. Kabir 《RSC advances》2018,8(57):32672
The site preference for ligand substitution in the benzothiazolate-bridged cluster HOs3(CO)10(μ-1,2-N,C-η1,κ1-C7H4NS) (1) has been investigated using PPh3. 1 reacts with PPh3 in the presence of Me3NO to afford the mono- and bisphosphine substituted clusters HOs3(CO)9(PPh3)(μ-1,2-N,C-η1,κ1-C7H4NS) (2) and HOs3(CO)8(PPh3)2(μ-1,2-N,C-η1,κ1-C7H4NS) (3), respectively. 2 exists as a pair of non-interconverting isomers where the PPh3 ligand is situated at one of the equatorial sites syn to the edge-bridging hydride that shares a common Os–Os bond with the metalated heterocycle. The solid-state structure of the major isomer establishes the PPh3 regiochemistry at the N-substituted osmium center. DFT calculations confirm the thermodynamic preference for this particular isomer relative to the minor isomer whose phosphine ligand is located at the adjacent C-metalated osmium center. 2 also reacts with PPh3 to give 3. The locus of the second substitution occurs at one of the two equatorial sites at the Os(CO)4 moiety in 2 and gives rise to a pair of fluxional stereoisomers where the new phosphine ligand is scrambled between the two equatorial sites at the Os(CO)3P moiety. The molecular structure of the major isomer has been determined by X-ray diffraction analysis and found to represent the lowest energy structure of the different stereoisomers computed for HOs3(CO)8(PPh3)2(μ-1,2-N,C-η1,κ1-C7H4NS). The fluxional behavior displayed by 3 has been examined by VT NMR spectroscopy, and DFT calculations provide evidence for stereoselective tripodal rotation at the Os(CO)3P moiety that serves to equilibrate the second phosphine between the two available equatorial sites.The site preference for PPh3 substitution in HOs3(CO)10(PPh3)2(μ-1,2-N,C-η1,κ1-C7H4NS) (1) has been investigated. 相似文献
13.
The β-selective asymmetric addition of γ-butyrolactam with cyclic imino esters catalyzed by a bifunctional chiral tertiary amine has been developed, which provides an efficient access to optically active β-position functionalized pyrrolidin-2-one derivatives in both high yield and enantioselectivity (up to 78% yield and 95 : 5 er). This is the first catalytic method to access chiral β-functionalized pyrrolidin-2-one via a direct organocatalytic approach.The asymmetric addition of γ-butyrolactam with cyclic imino esters catalyzed by (DHQD)2AQN has been developed, which provides an access to β-position functionalized pyrrolidin-2-one derivatives in high levels yield and enantioselectivity.Metal-free organocatalytic asymmetric transformations have successfully captured considerable enthusiasm of chemists as powerful methods for the synthesis of various kinds of useful chiral compounds ranging from the preparation of biologically important molecules through to novel materials.1 Chiral pyrrolidin-2-ones have been recognized as important structural motifs that are frequently encountered in a variety of biologically active natural and synthetic compounds.2 In particular, the β-position functionalized pyrrolidin-2-one backbones, which can serve as key synthetic precursors for inhibitory neurotransmitters γ-aminobutyric acids (GABA),3 selective GABAB receptor agonists4 as well as antidepressant rolipram analogues,5 have attracted a great deal of attention. Therefore, the development of highly efficient, environmentally friendly and convenient asymmetric synthetic methods to access these versatile frameworks is particularly appealing.As a direct precursor to pyrrolidin-2-one derivatives, recently, α,β-unsaturated γ-butyrolactam has emerged as the most attractive reactant in asymmetric organometallic or organocatalytic reactions for the synthesis of chiral γ-position functionalized pyrrolidin-2-ones (Scheme 1). These elegant developments have been achieved in the research area of catalytic asymmetric vinylogous aldol,6 Mannich,7 Michael8 and annulation reactions9 in the presence of either metal catalysts or organocatalysts (a, Scheme 1). These well-developed catalytic asymmetric methods have been related to the γ-functionalized α,β-unsaturated γ-butyrolactam to date. However, in sharp contrast, the approaches toward introducing C-3 chirality at the β-position of butyrolactam through a direct catalytic manner are underdeveloped (b, Scheme 1)10 in spite of the fact that β-selective chiral functionalization of butyrolactam can directly build up α,β-functionalized pyrrolidin-2-one frameworks.Open in a separate windowScheme 1Different reactive position of α,β-unsaturated γ-butyrolactam in catalytic asymmetric reactions.So far, only a few metal-catalytic enantioselective β-selective functionalized reactions have been reported. For examples, a rhodium/diene complex catalyzed efficient asymmetric β-selective arylation10a and alkenylation10b have been reported by Lin group (a, Scheme 2). Procter and co-workers reported an efficient Cu(i)–NHC-catalyzed asymmetric silylation of unsaturated lactams (b, Scheme 2).10c Despite these creative works, considerable challenges still exist in the catalytic asymmetric β-selective functionalization of γ-butyrolactam. First, the scope of nucleophiles is limited to arylboronic acids, potassium alkenyltrifluoroborates and PhMe2SiBpin reagents. Second, the catalytic system and activation mode is restricted to metal/chiral ligands. To our knowledge, an efficient catalytic method to access chiral β-functionalized pyrrolidin-2-one via a direct organocatalytic approach has not yet been established. Therefore, the development of organocatalytic asymmetric β-selective functionalization of γ-butyrolactam are highly desirable. In conjunction with our continuing efforts in building upon chiral precedents by using chiral tertiary amine catalytic system,11 we rationalized that the activated α,β-unsaturated γ-butyrolactam might serve as a β-position electron-deficient electrophile. This γ-butyrolactam may react with a properly designed electron-rich nucleophile to conduct an expected β-selective functionalized reaction of γ-butyrolactam under a bifunctional organocatalytic fashion, while avoiding the direct γ-selective vinylogous addition reaction or β,γ-selective annulation as outlined in Scheme 2. Herein we report the β-selective asymmetric addition of γ-butyrolactam with cyclic imino esters12 catalyzed by a bifunctional chiral tertiary amine, which provides an efficient and facile access to optically active β-position functionalized pyrrolidin-2-one derivatives with both high diastereoselectivity and enantioselectivity.Open in a separate windowScheme 2β-Selective functionalization of γ-butyrolactam via metal- (previous work) or organo- (this work) catalytic approach.To begin our initial investigation, several bifunctional organocatalysts13 were firstly screened to evaluate their ability to promote the β-selective asymmetric addition of γ-butyrolactam 2a with cyclic imino ester 3a in the presence of 15 mol% of catalyst loading at room temperature in CH2Cl2 (entries 1–6, Entry Cat. Solvent Yielde erf 1 1a CH2Cl2 70% 40 : 60 2 1b CH2Cl2 <5% 57 : 43 3 1c CH2Cl2 70% 65 : 35 4 1d CH2Cl2 68% 70 : 30 5 1e CH2Cl2 58% 63 : 47 6 1f CH2Cl2 71% 77 : 23 7 1f DCE 72% 80 : 20 8 1f CHCl3 70% 80 : 20 9 1f MTBE 68% 79 : 21 10 1f Toluene 63% 78 : 22 11 1f THF 45% 76 : 24 12 1f MeOH 32% 62 : 38 13b 1f DCE : MTBE 75% 87 : 13 14c 1f DCE : MTBE 72% 87 : 13 15d 1f DCE : MTBE 70% 85 : 15