Catalysis Science & Technology
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2020
·Vol. 10
·期 22
·7555-7565
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IF 5.721
Chenlin Ji,Suyun Jie,Pierre Braunstein,Bo-Geng Li
Aliphatic polyesters are a class of biorenewable, biocompatible, and biodegradable materials. The ring-opening polymerization (ROP) of lactones is one of the most powerful methods to access these materials. A novel series of benzoheterocyclic urea catalysts has been synthesized and characterized. When employed in the ROP of δ-valerolactone (δ-VL) in combination with 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), a fast and “living”/controlled feature was observed in both solvent-free polymerization and solution polymerization, which was proved by kinetic and chain extension experiments. With benzyl alcohol as an initiator, polyvalerolactones (PVLs) were obtained with different molecular weights and narrow molecular weight distributions. In addition, the PVLs with different topological structures were prepared by varying the initiators. The structure and thermal properties of resulting polymers were determined by NMR, GPC and DSC analyses. A possible mechanism was also proposed on the basis of NMR analysis.
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RSC Advances
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2020
·Vol. 10
·期 61
·37014-37022
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IF 3.119
Shengfu Liao,Jianguo Liu,Long Yan,Qiying Liu,Guanghui Chen,Longlong Ma
Anthraquinones are recognized as high efficiency photocatalysts which can perform various redox reactions in aqueous or organic phases. We have experimentally proven that 2-BrAQ can undergo hydrogen transfer with an alpha-aromatic alcohol under light conditions, thereby efficiently oxidizing the aromatic alcohol to the corresponding product. The yield of 1-phenethanol to acetophenone can reach more than 96%. In subsequent catalyst screening experiments, it was found that the electronegativity of the substituent at the 2 position of the anthraquinone ring and the acidity of the solvent affect the photocatalytic activity of anthraquinones. After using various aromatic alcohol substrates, 2-BrAQ showed good conversion and selectivity for most aromatic alcohols, but showed C–C bond cleavage and low selectivity with non-α-position aromatic alcohols. In order to explore the mechanism of the redox reaction of 2-BrAQ in acetonitrile solution, the corresponding free radical reaction pathway was proposed and verified by density functional theory (DFT). Focusing on calculations for 2-BrAQ during the reaction and the first-step hydrogen transfer reaction between the 2-BrAQ triplet molecule and the 1-phenylethanol molecule, we recognized the changes that occurred during the reaction and thus have a deeper understanding of the redox reaction of anthraquinone compounds in organic systems.
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JOURNAL OF ASIA-PACIFIC ENTOMOLOGY
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2020
·
IF 1.101
Jinhao Zhao,Zhongyan Wang,Zhongshan Li,Jiayu Shi,Ling Meng,Guorong Wang,Jingli Cheng,Yongjun Du
Aphids are among the most destructive phytophagous pests of host plants, because of their rapid reproduction, parthenogenesis, extensive crop damage, and the transmission of many plant viruses. Since lady beetles are important predatory natural enemies of aphids, developing lady beetle attractants to increase their field abundance is vital for aphid control. Floral volatiles and other semiochemicals are reportedly attractive to lady beetles. In this research, a total of 58 floral volatiles were tested by Y-tube olfactometer assays, among which 29 were highly attractive to both Harmonia axyridis (Coleoptera: Coccinellidae) and Coccinella septempunctata (Coleoptera: Coccinellidae). Meanwhile, the results of wind tunnel trials showed that only isoamyl acetate, α -humulene, trans -3-hexen-1-ol, methyl salicylate, and β -pinene lure these two species. Thereafter, 15 semiochemicals from pests, natural enemies, and pest-infested crops were mixed with the selected floral volatiles, to determine optimum formulations for attracting lady beetles through wind tunnels and further field trials. Eventually, formulas (1) α -humulene: β -pinene: methyl salicylate: trans -3-hexen-1-ol = 1:3:3:10; (5) α -humulene: β -pinene: methyl salicylate:1-nonanal = 1:3:3:10; (8) α -humulene: β -pinene: methyl salicylate: indole = 1:3:3:10 ( 1 , 5 , and 8 are labels used for the various formulations in field trials) were successfully verified to be attractive to lady beetles in both pumpkin and wheat fields. These formulations will be of great significance in developing integrated pest management strategies for aphid control.
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COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
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2020
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IF 6.444
Shixiang Zhou,Hui Mei,Mingyang Lu,Laifei Cheng
To cater to the complex needs in gas monitoring under harsh conditions, highly reliable and highly customized gas sensors with excellent sensing performance are in demand. Body-centered periodical mullite based ammonia sensors were fabricated by 3D printing for highly reliable ammonia detection. The printed substrates were modified with Ag nanoparticles decorated PANI network. NH 3 molecules can react with PANI to withdraw protons, leading to the localization of polarons and increasing the resistance. Additionally, the Ag nanoparticles provided more active sites for NH 3 molecules adsorption, enhancing the sensing performance. The sensor exhibited a response value of 9.7–100 ppm NH 3 and excellent selectivity at room temperature. More importantly, the sensors had an excellent mechanical performance with the compressive strength and energy absorption of 23.71 MPa and 243.09 kJ/m 3 , respectively, ensuring stable operation under stress. The strategy may shed light on the production of reliable and tailor-made gas sensors.
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ELECTROCHIMICA ACTA
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2020
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IF 6.215
Congcong Liu,Haijun Su,Chenyang Wei,Keyu Xie,Hongqiang Wang,Peng Zhai,Min Guo,Jun Zhang,Lin Liu
A high-quality TiO 2 electron transport layer (ETL) should possess a good energy-level alignment, perfect electron mobility, and excellent charge extraction efficiency. Nevertheless, the poor conductivity of amorphous TiO 2 film from low-temperature preparation is an inherent problem while the high-crystallined TiO 2 after high-temperature sintering (>450 °C) limits its application in the low-cost fabrication and flexible substrates. Here, we develop a low-temperature approach to in situ functionalize TiO 2 nanocrystals with dopamine molecules (DA-TiO 2 NCs) in the synthesis of the nanocrystals through a non-aqueous sol-gel method. We systematically investigate the tunable electronic properties of TiO 2 NCs with the variable DA modification and confirm that DA-TiO 2 can tailor the energy level alignment as well as increase the charge-extraction capacity, substantially reducing charge accumulation between the TiO 2 and perovskite layer. The in situ anchored amino groups (-NH 3 + ) not only preferentially boost the in-plane growth of perovskite grains but also induce the red-shift absorption of perovskite via the strong electrostatic interaction with Br − ions. Based on the DA-TiO 2 NCs ETLs, the power conversion efficiency of the fully ambient-processed planar FA x MA 1-x PbBr y I 3-y PSCs is optimized to 19.45%.
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Journal of Materials Chemistry A
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2020
·Vol. 8
·期 23
·11859-11866
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IF 11.301
Yafeng Xu,Jialong Duan,Xiya Yang,Jian Du,Yudi Wang,Yanyan Duan,Qunwei Tang
The electron-transporting layer (ETL) plays a non-negligible role in determining the charge extraction and transfer behaviors from perovskite films under solar irradiation for high efficiency perovskite solar cells. A suitable band structure, good conductivity, high electron mobility and low trap state density are preferred for the desired ETL to maximize the electricity generation and minimize the charge recombination. Herein, we have demonstrated that the incorporation of antimony (Sb) dopants into the lattice of low-temperature processed TiO2 nanocrystals can effectively suppress the formation of under-coordinated Ti3+ and oxygen vacancies, leading to improved electronic conductivity and mobility. When assembling into all-inorganic, carbon-based CsPbBr3 planar perovskite solar cells free of noble metal electrodes, an enhanced efficiency of 8.91% with an ultra-high open-circuit voltage of 1.654 V and reduced hysteresis from 32% to 15% is achieved based on the Sb-doped TiO2 ETL. The mechanism behind this phenomenon is mainly attributed to the improved perovskite film quality and significantly reduced charge recombination. Taking the advantages of low temperature, low defect state density, high electrical conductivity and mobility into consideration, the Sb-doped TiO2 ETL demonstrates great potential in advanced perovskite solar cells even in flexible devices.
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CHEMICAL ENGINEERING JOURNAL
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2020
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IF 10.652
Yi Xia,Jie Shi,Qian Sun,Dan Wang,Xiao-Fei Zeng,Jie-Xin Wang,Jian-Feng Chen
Colloidal nanocrystals can offer exquisite control of physical and chemical properties for technological applications by tuning their sizes, shapes and crystal forms. Herein, a convenient phase-transfer route was presented to controllably prepare transparent dispersions of monodispersed ZrO 2 nanocrystals in an aqueous-organic two-phase medium. By adjusting the surfactants, solvents and basicity, the controllability of crystal forms from monoclinic to tetragonal phases, the particle length from 5 to 20 nm, and the different shapes including spindle, cobblestone, sphere, branch, rod and cube can be achieved. The as-prepared ZrO 2 nanocrystals can be readily dispersed in nonpolar solvents, thereby forming the ultra-highly concentrated (60 wt%), highly stable (>18 months) and highly transparent nanodispersions. Density functional theory (DFT) calculations were further used to elucidate the root causes of underpinning growth mechanisms. This work not merely enriches the methodology of controllable fabrication of monodispersed sub-10 nm ZrO 2 nanocrystals, but also enables a platform to synthesize rare-earth-doped nanophosphors using ZrO 2 as the host matrix. The fluorescent ZrO 2 :Yb 3+ /Er 3+ nanocrystals, which can be easily monodispersed in organic solvents, were also prepared with visible luminescene properties under near-infrared irradiation.
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JOURNAL OF CATALYSIS
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2020
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IF 7.888
Haiping Li,Tianxing Yang,Yiwei Jiang,Shuai Chen,Yufei He,Junting Feng,Dianqing Li
A feasible method for spontaneous in situ reductions on layered double hydroxides (LDHs) to prepare supported catalysts with Pd sub-nanoparticles is proposed. In this process, the reductive sites for the Pd 2+ are introduced into the LDHs laminates in a highly dispersed distribution, and a series of reductive supports (such as CoAl-LDHs, CoNiFe-LDHs, FeAl-LDHs) are prepared. The obtained reductive support is directly used to reduce Pd precursor without the addition of a reducing agent. HRTEM images show that metallic Pd is successfully reduced and evenly distributed on the support. Moreover, hexadecyl trimethyl ammonium chloride (CTAC) is introduced to improve the dispersion of Pd. HAADF-STEM results illustrate that metallic Pd particles are prepared in the form of a sub-nanometer size. XPS analysis show that Co and Pd species undergo a redox reaction and have an electronic interaction with CTAC. The factors affecting the nucleation and growth of Pd sub-nanoparticles in CTAC-modified support spontaneous in-situ redox are also discussed. The obtained Pd MI /CoAl-LDHs (prepared by modified support spontaneous in situ redox method (MI)) is applied to the selective oxidation of benzyl alcohol. It is found that the selectivity is 91% at a conversion of 92%, and turnover frequency (TOF) of Pd MI /CoAl-LDHs is 2.2 times higher than that of Pd D /MgAl-LDHs prepared by the common dipping method. Furthermore, Pd MI /CoAl-LDHs shows excellent stability in 5 times reusability and 150 h use, demonstrating the Oswald ripening of Pd particles can be effectively prevented.
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JOURNAL OF SOLUTION CHEMISTRY
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2020
·Vol. 49
·期 2
·145-165
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IF 1.273
Yang Xuzhao,Wang Jun,Fang Yun
Asymmetrical ammonium-based gemini ionic liquids, 1-trimethylammonium-3-(1-methylpiperidinium)propane dibis[(trifluoromethyl)sulfonyl]imide ([N 111 C 3 MPip][NTf 2 ] 2 ) and 1-trimethylammonium-3-(4-methylmorpholinium)propane dibis[(trifluoromethyl)sulfonyl]imide ([N 111 C 3 MMor][NTf 2 ] 2 ), were synthesized and structurally characterized by 1 H NMR, 13 C NMR, and MS. The melting temperatures and associated enthalpies and entropies of fusion of these gemini ionic liquids have been determined through differential scanning calorimetry (DSC). Thermal stabilities of [N 111 C 3 MPip][NTf 2 ] 2 and [N 111 C 3 MMor][NTf 2 ] 2 have been investigated by thermogravimetric analysis technology under pure nitrogen atmosphere. The solubility data of [N 111 C 3 MPip][NTf 2 ] 2 and [N 111 C 3 MMor][NTf 2 ] 2 in water, ethanol, benzyl alcohol, 2-phenylethanol and n -heptane were determined by a synthetic method using a laser monitoring observation technique in the temperature range 298.15–333.15 K under atmospheric pressure. The solubility in all pure solvents increased with the increasing temperature and the greatest solubilities of both gemini ionic liquids were observed in benzyl alcohol. The modified Apelblat, Buchowski–Ksiazaczak λh and NRTL models were employed to correlate the experimental solubility data. The calculated results show good agreement with the experimental data and modified Apelblat and λh equations are more accurate than the NRTL model. The standard state enthalpy, entropy, and Gibbs energy of dissolution of the GILs in the studied solvents were evaluated through the van′t Hoff equation using the experimental solubility data. The excess enthalpies of the solutions were also determined by the λh model. The dissolution behavior can serve for the synthesis and purification process of GILs.
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JOURNAL OF CATALYSIS
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2020
·
IF 7.888
Yang Xu,Jin Li,Jian Zhou,Yufeng Liu,Zhuojun Wei,Hui Zhang
The effects of size and active site structure on catalytic activity were deeply investigated in air oxidation of benzyl alcohol over a series of Ni 3 Al-LDH (layered double hydroxides)-supported Au n nanocluster (NC) catalysts Au n /LDH (n = 25, 38, ~127), obtained by modified electrostatic adsorption of atomically precise Au 25 Capt 18 , Au 38 Capt 24 and Au ~127 -Capt (Capt: captopril) NCs followed proper calcination. Detailed characterizations show that the Au 25 /LDH, Au 38 /LDH and Au ~127 /LDH possess ultrafine Au NCs size of 1.2 ± 0.2, 1.4 ± 0.3 and 1.8 ± 0.5 nm, respectively, which are majorly dispersed on the edge sites of the small-sized LDH nanosheets (20–40 nm). All the catalysts exhibit excellent catalytic activities in air oxidation of benzyl alcohol without external base associated with the remarkable size- and active site structure-dependence. The catalyst Au 38 /LDH shows the highest activity with TOF of 1884 h −1 , which can be attributable to the ultrafine bi-icosahedron structure Au 38 NCs and the strongest Au 38 NCs – Ni-OH (LDH) synergistic effect facilitating the activation of α-C H bond of benzyl alcohol over more negatively charged Au sites upon XPS, CO-DRIFTs and kinetic isotope studies. The findings of the size- and active site structure-dependence of supported Au n cluster catalysts in the oxidation of benzyl alcohol provide important guiding principles for the rational design of supported Au n cluster catalysts.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2020
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IF 7.489
Yi Xiao,Ting Wang,Ganhua Qiu,Kun Zhang,Changguo Xue,Benxia Li
Photocatalytic reactions represent a kind of green and sustainable chemical processes for organic transformations, but the efficiency is limited by the severe recombination and/or inadequate redox potentials of photoinduced charge carriers in photocatalysts . To address these issues, herein, the CdS-EDTA/g-C 3 N 4 heterostructures were designed according to Z-scheme photocatalytic mechanism and synthesized by the hydrothermal growth of CdS on g-C 3 N 4 nanoflakes with assistance of EDTA chelating agent. EDTA played multiple roles in the formation of CdS-EDTA/g-C 3 N 4 heterostructure photocatalysts, such as controlling the morphology of CdS nanostructures , linking CdS and g-C 3 N 4 together, and boosting the charge transfer between two semiconductors. The optimized CdS-EDTA/g-C 3 N 4 (10%) photocatalyst exhibited much higher activities toward the selective reduction of nitrophenol and the selective oxidation of benzyl alcohol , than those of CdS/g-C 3 N 4 heterostructures without EDTA. The enhanced photocatalysis of CdS-EDTA/g-C 3 N 4 can be ascribed to the efficient separation and suitable photoredox potentials of photoexcited charge carriers in the EDTA-bridged Z-scheme system. This work provides the inspiration for exploring inexpensive organic electron mediators for constructing all-solid-state Z-scheme photocatalysts and demonstrates the enhanced performance of Z-scheme photocatalysts for photoredox reactions of organic transformations.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2020
·
IF 16.683
Qiong Lin,Yue-Hua Li,Ming-Yu Qi,Jing-Yu Li,Zi-Rong Tang,Masakazu Anpo,Yoichi M.A. Yamada,Yi-Jun Xu
The photocatalytic coupling reaction can be conducted in one pot to realize the simultaneous utilization of electrons and holes, thereby obtaining value-added fine chemicals and fuels. Herein, we report a binary nickel modified ZnIn 2 S 4 (Ni:ZIS) for highly efficient photocatalytic selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD) integrated with hydrogen (H 2 ) evolution, in which Ni can promote photogenerated charge transfer for enhancing photoactivity. Particularly, the products of converting BA to aromatic compounds over blank ZnIn 2 S 4 (ZIS) and Ni:ZIS show a marked difference under the same reaction conditions. Hydrobenzoin (HB) is the primary product over blank ZIS. After the introduction of Ni, the formation of HB is dramatically suppressed, resulting in higher selectivity of BAD, because the introduction of Ni facilitates the α-H abstraction. In addition, an analogous phenomenon has been observed on Ni-based compounds modified ZIS, such as Ni x P and NiS. It is hoped that this work would provide a feasible paradigm for modifying the surface of photocatalysts to tune the selectivity of product-oriented alcohols oxidation coupled with H 2 evolution in water.
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