ChemCatChem
·
2019
·Vol. 11
·期 6
·1610-1614
·
IF 4.495
Qiao Han,Peidong Li,Yanfei Zhang,Peng Lu,Li Xu,Hongchen Guo,Lei Xu
Graphical Happy couple ! The coupling of methanol dehydrogenation and side-chain alkylation of toluene realizes high selective conversion of toluene with methanol into styrene (ST) and ethylbenzene (EB) by composite catalysts combining CsX with methanol dehydrogenation components, wherein the thermodynamic driving force for dehydrogenation of methanol was a key point for the coupling reaction. A new strategy, the coupling of methanol dehydrogenation and side-chain alkylation of toluene, to realize highly effective conversion of methanol and toluene into styrene and ethylbenzene was proposed. A series of composite catalysts were designed by combining CsX with numerous catalysts reported to be effective for methanol dehydrogenation to formaldehyde. The studies of side-chain alkylation of toluene with methanol over these composite catalysts indicated that the introduction of methanol dehydrogenation components could universally improve the yield of styrene and ethylbenzene in side-chain alkylation of toluene with methanol. And the introduction of some methanol dehydrogenation components, i. e. sodium borate (Na 2 B 4 O 7 ) and CuO/SiO 2 , could even double the yield of styrene and ethylbenzene. Furthermore, the influence of the mass ratio of different components and the spatial arrangement of different active sites on composite catalysts was investigated in detail.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2019
·
IF 3.131
Mingcheng Li,Jingyu Zhao,Yaru Li,Meichen Li,Yongchuan Wu,Chun Wang,Han Jiao,Ping Na
Cesium ions (Cs + ) were absorbed using electrochemically switched ion exchange (ESIX) method based on Na 2 Ti 3 O 7 nanotubes , which were synthesized on surface of foam titanium plate by one-step hydrothermal method (TNT-F). SEM, TEM, XRD , Raman and XPS were used to characterize the TNT-F. During the adsorption process , the effects of adsorption potential, initial Cs + concentration, pH value and competing ions were investigated. It was found that the application of electric field force can effectively promote the adsorption process. Furthermore, pH value and competitive ions have a slight effect on the adsorption process. The desorption ability of TNT-F was also considered. The experimental results show that the desorption ratio also can be greatly improved by applying potential. In addition, TNT-F has a good reusability and reproducibility, it also has good adsorption performance under high concentration of competitive ions. In a word, the high performance TNT-F electrode which was easy to obtain in low cost is expected to become a promising material for Cs + collection.
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Crystals
·
2019
·Vol. 9
·期 5
·258
·
IF 2.061
Hongdan Zhang,Ludan Zhu,Jun Cheng,Long Chen,Chuanqi Liu,Shuanglong Yuan
The Cs2SnX6perovskites have attracted much attention due to excellent optoelectronic properties and high stability. In the present work, we have focused on the morphology control and photoluminescence characteristics of the Cs2SnCl6perovskite crystals. The synthesis process of the Cs2SnCl6crystals includes two stages composed of the formation of initial crystals and the growth of Cs2SnCl6; the later originated from the oxidization of CsSnCl3. This process has been confirmed by Scanning electron microscope (SEM) and X-rays diffraction (XRD). By controlling the concentration of the initial reactants and hydrochloric acid in the solution to change the supersaturation of the solution, different crystal morphologies, such as truncated octahedron, octahedron, hexapod, quasi-sphere, have been obtained. In relatively a low supersaturation solution, the amount of growth units dominates the crystal growth process to obtain the hexapod and self-assembly crystals. In contrast, in relatively high supersaturation solution, nucleation predominates to yield small size truncated octahedrons and near-spherical Cs2SnCl6crystals. The synthesized Cs2SnCl6crystals have shown a wide emission band peaking at 450 nm with full width at half maximum (FWHM) 63 nm due to the defects introduced by Sn2+. The photoluminescence intensities of crystals synthesized at various conditions exhibited considerable difference, which was about 60 times between the highest and the lowest.Keywords:lead-free perovskite;Cs2SnCl6;crystal growth;photoluminescence
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
·
IF 3.375
Xingwen Liu,Qi Wang,Zhuo Wang,Xueting Liu,Minghui Zhang,Jiahui Fan,Zhiyong Zhou,Zhongqi Ren
A new type of Rb(I) ion imprinting material was prepared with methacrylic acid as functional monomer, Rb(I) ion as template, and methanol/acetonitrile as solvent. The polymerization reaction was initiated by N,N-azobis(isobutyronitrile) (AIBN) with the cross-linking by ethylene glycol dimethacrylate (EGDMA). In addition, benzo-12-crown-4-ether (B12C4) was introduced as a ligand to fix the template ions better. Scanning electron microscope, Zeta potential analysis, Fourier transform infrared spectrum, thermogravimetric analysis, and energy dispersive spectra were used for characterization of the imprinted polymer. Effects of preparation and adsorption conditions on adsorption performances of Rb(I) ion-imprinted polymers (IIPs) were investigated. The imprinted polymer had fast adsorption kinetics (reaching equilibrium within 15 min) and high maximum adsorption capacity (129.9 mg·g–1) at pH 9.5. Besides, the adsorption process conformed to pseudo-second-order kinetic and Freundlich isotherm models. Moreover, the prepared Rb(I)-IIPs showed high selectivity for Rb(I) ions. The results of eight repeated cycles of adsorption–desorption demonstrated that the prepared Rb(I)-IIPs had good stability and reusability.
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Advanced Optical Materials
·
2019
·Vol. 7
·期 10
·1900139
·
IF 7.125
Jun Zhou,Jiajun Luo,Ximing Rong,Peijia Wei,Maxim S. Molokeev,Yang Huang,Jing Zhao,Quanlin Liu,Xiuwen Zhang,Jiang Tang,Zhiguo Xia
Lead-free and stable Sn halide perovskites demonstrate tremendous potential in the field of optoelectronic devices. Here, the structure and optical properties of the “defect” perovskites Cs 2 SnCl 6− x Br x are reported, as well as their use as photodetector materials. Millimeter-sized Cs 2 SnCl 6− x Br x single crystals are grown by the hydrothermal method, with the body color continuously changing from transparent to yellow and finally to dark red. Narrowband single-crystal photodetectors using Cs 2 SnCl 6− x Br x crystals are presented, which show a high detectivity of ≈2.71 × 10 10 Jones, with narrowband photodetection (full-width at half-maximum ≈45 nm) and high ion diffusion barriers. Moreover, the response spectra are continuously tuned from near violet to orange depending on the variation of the bandgap of the single crystals by changing the halide compositions. The strong surface charge recombination of the excess carriers near the crystal surfaces produced by short wavelength light elucidates the narrowband photodetection behavior. This work provides a new paradigm in the design of lead-free, stable, and high-performance perovskite derivatives for optoelectronics applications.
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Science China-Chemistry
·
2019
·Vol. 62
·期 10
·1405-1413
·
IF 6.085
Han Peigeng,Zhang Xue,Mao Xin,Yang Bin,Yang Songqiu,Feng Zhaochi,Wei Donghui,Deng Weiqiao,Pullerits Tõnu,Han Keli
Lead-free halide double perovskites have gathered wide scientific interest since they are environmentally friendly and stable. However, compared to the lead perovskites, their optoelectronic properties are compromised. Herein we report a series of bulk lead-free mixed Bi-In halide double perovskites: Cs 2 AgBi 1− x In x Cl 6 (0< x <1). The Cs 2 AgBi 0.125 In 0.875 Cl 6 breaks the parity-forbidden transition and retains direct band gap structure, having warm-white light emission, with photoluminescence quantum efficiency (PLQE) of 70.3%, much higher than the PLQE of reported lead perovskite materials. Its exciton self-trapping dynamics is investigated. Meanwhile, the Cs 2 AgBi 0.125 In 0.875 Cl 6 nanocrystals and Cs 2 AgBi 0.125 In 0.875 Cl 6 microcrystals can be synthesized by modified hot injection and rapid cooling crystallization, respectively. The size effect of Cs 2 AgBi 0.125 In 0.875 Cl 6 is studied on the photoluminescence (PL) property. Additionally, the bulk material exhibits excellent stability on exposure to light, humidity and air for more than 3 months. It is a promising candidate as highly efficient warm white-light emitting material for road lighting.
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Advanced Optical Materials
·
2019
·Vol. 7
·期 8
·1801435
·
IF 7.125
Jun Zhou,Ximing Rong,Peng Zhang,Maxim S. Molokeev,Peijia Wei,Quanlin Liu,Xiuwen Zhang,Zhiguo Xia
The halide double perovskite family represented by A 2 (B + ,B 3+ )X 6 can overcome the lead toxicity and enable generally large band gap engineering via B/B sites' transmutation or exotic dopants to fulfill the emerging applications in the optoelectronic fields. Herein, the design and the experimental synthesis of a new family of Mn 2+ -doped Cs 2 NaBi 1- x In x Cl 6 crystals with an intense orange-yellow emission band are reported, and the phase formation stability is discussed via a combined experimental–theoretical approach. Depending on the manipulation of Bi 3+ /In 3+ combination, the band gap increases with In 3+ content, and a subsequent evolution from indirect to direct band gap is verified. First-principles calculations and parity analyses indicate a parity forbidden effect on Cs 2 NaInCl 6 , and a combination effect of absorption on Cs 2 NaBi 1- x In x Cl 6 from both Cs 2 NaBiCl 6 and Cs 2 NaInCl 6 . The associated Mn 2+ -doped photoluminescence depending on the Bi 3+ /In 3+ substitution is also addressed from the variation of the different Mn–Cl environment and neighboring-cation effect.
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DYES AND PIGMENTS
·
2020
·
IF 4.613
Xiaotian Yuan,Yujiao Tu,Wei Chen,Zhiwei Xu,Yunlin Wei,Kunhao Qin,Qi Zhang,Yingying Xiang,Hongcai Zhang,Xiuling Ji
A highly photoluminescent small-size carbon dots (CDs) deriving ampicillin sodium were successfully obtained via one-step hydrothermal method . The prepared CDs showed uniform particle size and possessed good excitation-dependent characteristic. The dead bacteria and yeast cells could be selectively stained by the CDs, but the live ones not. It indicated that the CDs possessed a good potential for the live/dead bacteria and yeast differentiation. Cell and plant leaf imaging showed that the prepared CDs possessed low biotoxicity, excellent biocompatibility and multicolor fluorescence emission properties making it a good candidate for bioimaging application. The probe exhibited high selectivity and sensitivity to detect Hg(II) and 2,4-dinitrophenol (2,4-DNP), and excellent linear range of 0–50 μM for Hg(II) (R 2 = 0.9920) and 0–25 μM for 2,4-DNP (R 2 = 0.9919), with low detection limits of 33.40 nM and 13.44 nM for Hg(II) and 2,4-DNP, respectively. It revealed that dynamic quenching mechanism dominated in Hg(II) quenching the CDs fluorescent, while the quenching mechanism of 2,4-DNP detection belonged to the inner filter effect. The sensor was successfully applied to determine the Hg(II) and 2,4-DNP in real water samples. It shows that the fluorescent nanoprobe shows great promising potential for the detection of environmental pollutants.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Xingyu Liu,Jinwei Gao,Wanqiang Liu,Qianming Wang
Lead halide perovskites have generated remarkable progress in a wide variety of opto-electronic fields. However, challenging issues including water-sensitive feature, poor stability over temperature change and mechanical fragility should be circumvented to enable the practical uses of such nanocrystals . Ethylene-propylene-diene monomer (EPDM) rubber, which possesses saturated and nonpolar polymeric chain, has been extensively explored in industry due to its sealing property, low-cost, dynamic and outstanding abrasive resistance. In this study, the hybrid inorganic-organic network with covalent cross-linkages and CsPbX 3 (X = Cl and Br) quantum dots has been established in EPDM rubber system via an effective and mild approach in the process of mixing reaction at room temperature. In contrast to pure perovskite dots, the peak emission intensity of CsPb(Cl 0·25 Br 0.75 ) 3 -EPDM can be well maintained after it has been immersed into aqueous solution for 2 h. Moreover, the water-mediated treatment will control the emission color evolution from cyan (485 nm) to green (510 nm) and such process can be fully reversible during the soaking and drying cycles. In addition, the employment of such polymeric host with superior heat resistance results in significant increases in thermal stability, mechanical strength and toughness. This efficient strategy will provide a rational design of reinforcing photoluminescence for all-inorganic perovskite quantum dots in numerous applications.
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OPTICAL MATERIALS
·
2019
·
IF 2.687
Sen Yang,Shangxuan Huang,Qi Wang,Ruirui Wu,Qiuju Han,Wenzhi Wu
Cs 2 Ag x Na 1-x InCl 6 microcrystals (MCs) are synthesized using a solvothermal method. The regular variation of Na incorporation is characterized according to the intensity change of the X-ray diffraction and ultraviolet visible absorption peaks. Temperature-dependent photoluminescence (PL) properties of Cs 2 Ag x Na 1-x InCl 6 MCs are studied by use of steady-state PL and time-resolved PL (TRPL) measurements. From steady-state PL, it is verified that the white-light emission primarily originates from self-trapped excitons (STEs) at low temperature (80–290 K). When the electron-phonon interactions become stronger, STEs are promoted to generate from free excitons (FEs). And the high temperature-dependent (293–450 K) PL reveals the thermal quenching process. Temperature-dependent TRPL demonstrates that the change of lifetimes is attributed to band-edge FEs state and STEs state. It is found that the electrically-driven PL decreases to 70% then becomes stable from 0 to 120 min when light-emitting diodes (LEDs) are fabricated to explore the thermal stability. Our results suggest these white-emission Cs 2 Ag x Na 1-x InCl 6 MCs can be used as excellent materials for LEDs and provide reference to engineer such MCs toward practical optoelectronic applications .
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Inorganic Chemistry Frontiers
·
2019
·Vol. 6
·期 12
·3621-3628
·
IF 5.934
Fangyi Zhao,Zhen Song,Jing Zhao,Quanlin Liu
Searching for high performance and broader applications of inorganic halide perovskites has drawn extensive attention. In this work, a Cr3+-doped halide perovskite, Cs2AgInCl6:Cr3+, which exhibits broadband near-infrared (NIR) emission is first obtained via the traditional high temperature solid-state reaction. A broad emission band ranging from 850 to 1350 nm centered at 1010 nm with a full-width at half-maximum (FWHM) of 180 nm is assigned to the spin-allowed 4T2 → 4A2 transition of octahedrally coordinated Cr3+ ions in a very weak crystal-field environment. The excitation bands centered at 353, 565 and 800 nm can be attributed to the absorption of the Cs2AgInCl6 host, the Cr3+ d–d transitions of 4A2 → 4T1 and 4A2 → 4T2, respectively. Upon 760 nm excitation, the photoluminescence quantum yield (PLQY) of Cs2AgIn0.9Cl6:0.1Cr3+ is about ∼22.03%. Cs2AgInCl6:Cr3+ phosphors with such broadband NIR emission have potential in phosphor converted light emitting diodes (pc-LEDs) which have applications in bioimaging and biomonitoring.
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Catalysis Science & Technology
·
2018
·Vol. 8
·期 13
·3346-3356
·
IF 5.365
Peidong Li,Qiao Han,Xiaomin Zhang,Yangyang Yuan,Yanfei Zhang,Hongchen Guo,Li Xu,Lei Xu
Side-chain alkylation of toluene with methanol is a potential technology to realize the one-step production of styrene under mild conditions. Herein, a series of cesium X zeolites with different cesium contents were prepared through an ion-exchange method. The performance of the CsX zeolites was extensively investigated in the side-chain alkylation of toluene and methanol. The acid–base properties of the involved CsX were characterized and the results showed that the acid–base properties present regular changes with varied cesium contents. Based on the full understanding of the acid–base properties of the involved CsX, the reaction behaviors of the main and side reactions in the side-chain alkylation of toluene with methanol over CsX were investigated and new insights were revealed. It has been found that the crucial steps for the main reactions were the activation of toluene and the formation of formaldehyde from dehydrogenation of methanol when the cesium exchange degree of CsX was lower and higher than 32.3%, respectively. The hydride transfer reaction between styrene and carbon deposition is responsible for the formation of ethylbenzene over CsX with lower cesium contents, while the transfer hydrogenation of styrene with methanol and formaldehyde was the main path for ethylbenzene formation over CsX with higher cesium contents. And it was found that the existence of Brønsted acid sites accounts for the formation of xylene over CsX. These new findings will give a new insight into the reaction behaviors of the side-chain alkylation of toluene with methanol over CsX and may also provide a potential modification method for high-efficiency catalysts.
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