ChemSusChem
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2019
·Vol. 12
·期 21
·4824-4831
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IF 7.804
Qixin Zhuang,Guofeng You,Lijun Wang,Xinyu Lin,Ding Zou,Hongyu Zhen,Qidan Ling
Graphical Cheap plastic in solar cells ! TiO 2 nanoparticles-based perovskite solar cells (PVSCs) with a polystyrene (PS) interface modification layer and a poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) hole-transporting layer exhibit encouraging photovoltaic performances and stabilities. The use of a cheap plastic material in PVSCs would allow the fabrication of low-cost PVSCs for commercial use Interface engineering of TiO 2 nanoparticles (NPs)-based perovskite solar cells (PVSCs) is often necessary to facilitate the extraction and transport of charge carriers. In this work, poly[{9,9-bis[3′-( N , N -dimethyl)propyl]-2,7-fluorene}- alt -2,7-(9,9-dioctylfluorene)] (PFN) and polystyrene (PS) are demonstrated to be effective surface modifiers of the TiO 2 NPs electron-transporting layer in n-i-p PVSCs. The low-cost insulating polymer PS performs better than the PFN conjugated polymer owing to its high film quality, low surface energy and insulating characteristics. A peak power conversion efficiency (PCE) of 15.09 % with an open-circuit voltage ( V OC ) of 1.05 V and a PCE of 17.13 % with an ultrahigh V OC of 1.18 V is achieved with TiO 2 NPs/PS-based PVSCs using poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and spiro-OMeTAD, respectively, as the hole-transporting material.
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Nanoscale
·
2019
·Vol. 11
·期 38
·17736-17745
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IF 6.97
Qian Zhu,Fushan Wang,Fengwei Zhang,Zhengping Dong
The direct oxidation of alcohols to esters through a green and cost-effective strategy is a fascinating chemical synthesis route. In this study, an environmentally friendly N-doped porous carbon encapsulated Co-based nano-catalyst was prepared via a simple carbonization procedure, utilizing renewable chitosan, accessible dicyandiamide and low-cost Co(OAc)2 as co-precursors. The obtained Co@NC-2-T catalysts were successfully used in selective oxidation of aromatic alcohols with methanol to esters under atmospheric reaction conditions. The Co@NC-2-900 catalyst (added with 2 g dicyandiamide and pyrolyzed at 900 °C) shows optimal activity and applicability and can also be reused at least six times in the oxidative esterification of aromatic alcohols with excellent stability. The presence of superoxide anion radicals in the current catalytic system was detected by the EPR method, and a possible mechanism of alcohol oxidation to ester was proposed on this basis. Thus, this study provides a facile, eco-friendly, and highly efficient catalytic system for oxidative esterification of alcohols.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2019
·
IF 14.229
Junhua Zou,Zhitong Wang,Wei Guo,Binbin Guo,Yan Yu,Ling Wu
ZnTi-LDH nanosheets have been synthesized as photocatalysts for selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD) under visible light irradiation. Based on UV–vis DRS, in-situ FTIR and XPS results, it was revealed that BA would be efficiently chemisorbed and activated on ZnTi-LDH forming the surface coordination species, which contributed to harvesting visible light and induced the photocatalytic reaction. The ESR spectra suggested that oxygen vacancies would be produced in ZnTi-LDHs after the adsorption of BA molecules. More exposed surface OH groups would induce more oxygen vacancies, which would serve as the centers for capturing photoelectrons from the photoexcited surface coordination species and act as active sites for enhanced O 2 adsorption and activation, resulting outstanding photocatalytic activity. Finally, a possible mechanism was proposed to illustrate the photocatalytic process which mediated by surface coordination species formed by the interaction between ZnTi-LDH and BA.
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EUROPEAN POLYMER JOURNAL
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2019
·
IF 3.621
Rui Feng,Suyun Jie,Pierre Braunstein,Bo-Geng Li
The ring-opening polymerization (ROP) of lactones is an effective method for the preparation of biocompatible and biodegradable aliphatic polyesters, for which the development of efficient organocatalysts with high activity and good controllability is highly desirable. A series of novel pyridyl-urea catalysts has been synthesized and applied in the solvent-free ROP of lactones and trimethylene carbonate. Combined with 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), the pyridyl-urea/MTBD systems showed a fast and living/controlled behavior in the ROP, generating polymers with narrow molecular weight distributions. The influences of catalyst structure, type of base, pyridyl-urea/base ratio, feed ratio of monomer/initiator and reaction temperature on the catalytic properties were investigated. A possible mechanism was proposed on the basis of NMR titration and dilution experiments.
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JOURNAL OF SUPERCRITICAL FLUIDS
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2019
·
IF 3.481
Di Duan,Baogen Su,Zongbi Bao,Yiwen Yang,Qilong Ren
A series of highly CO 2 -soluble open-chain crown ether bridged diphosphates were designed and prepared as chelating ligands which were used to extract lanthanide ions from cellulose paper into supercritical CO 2 (ScCO 2 ). These ligands were designed by introducing different ester side chains and joining the two phosphorus groups with different length of ethylene oxide group which could provide enhanced solubility and complexation ability. The solubility data of these synthesized diphosophates in ScCO 2 were measured at 313.15 K and 10.65 MPa–13.69 MPa. Lanthanides metal ions including La 3+ , Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Gd 3+ , Er 3+ , and Yb 3+ were successfully removed from the solid matrix by supercritical fluid extractions using these chelating ligands at 313.15 K and 20 MPa. The extraction efficiency of metal ion was affected by chelating ligands’ side chain, which increased from 68% to 94% mainly driven by the increased solubility capability.
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MACROMOLECULES
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2019
·
IF 5.997
Na Zhao,Chuanli Ren,Yong Shen,Shaofeng Liu,Zhibo Li
Degradable long-chain aliphatic polyesters are promising alternatives to polyolefins. The ring-opening polymerization (ROP) of ω-pentadecalactone (PDL) enables the synthesis of aliphatic polyesters with melting temperature close to low-density polyethylene (LDPE). However, this ROP reaction is of great challenge because of low ring strain of the PDL monomer. The occurrence of intra- and intermolecular transesterification reactions during ROP made it difficult to prepare well-defined block copolyesters for advanced properties. In this context, cyclic trimeric phosphazene base (CTPB) in combination with benzyl alcohol (BnOH) was proved to be an efficient initiator system for ROP of PDL, showing an excellent polymerization rate (TOF up to 600 h–1) at 80 °C. Well-defined diblock copolyesters, i.e., PPDL-b-PLLA, can be easily synthesized by sequential addition of PDL and l-lactide (L-LA). In contrast, sequential addition of PDL and ε-caprolactone (CL) or δ-valerolactone (VL) only led to the random copolyesters under the same conditions. On the other hand, CTPB is an inherent tribasic superbase and can be partially neutralized to decrease its basicity for better control over active lactones such as CL and VL. Hence, we introduced 0.33–1.0 equiv of benzoic acid (PhCOOH) relative to CTPB and demonstrated that it can diminish the transesterification during ROP of CL or VL. Based on this strategy, PPDL-b-PCL or PPDL-b-PVL diblock copolyesters were successfully prepared by sequential addition of monomers of CL or VL after ROP of PDL. The block copolyester structures were confirmed by the 13C NMR spectroscopy and DSC characterizations.
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ChemCatChem
·
2019
·Vol. 11
·期 6
·1779-1788
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IF 4.495
Wei Zhang,Ziqiang Xiao,Jiajun Wang,Wenqin Fu,Rong Tan,Donghong Yin
Graphical Alloys of Catalysis ! Synergistic effect in Au−Pd alloy catalysts enhanced selective aerobic oxidation of alcohols using air at atmospheric pressure in water. A series of bimetallic Au−Pd alloy nanoparticles (NPs) with varied Au/Pd molar ratios was supported on Gamma-alumina (γ-Al 2 O 3 ) surface through the co-impregnation-reduction method using HAuCl 4 and PdCl 2 as metal precursors. Characterization results suggested the high dispersion of Au−Pd alloy NPs, as well as the interplay between the two compositions. Benefitting from the synergistic effects of Au−Pd alloying, the bimetallic Au-Pd x @γ-Al 2 O 3 catalysts were highly efficient for selective aerobic oxidation of various alcohols either aromatic or aliphatic in water using air at atmospheric pressure as a sole oxidant without the need for any cocatalyst. Quantitative yields of corresponding aldehydes or ketones were achieved over Au-Pd 1.2 @γ-Al 2 O 3 within 2 h, whereas pure Au@γ-Al 2 O 3 or Pd@γ-Al 2 O 3 was far less efficient. More importantly, the “alloying effect” appeared to stabilize the bimetallic NPs against aggregation and poisoning, which made the Au-Pd x @γ-Al 2 O 3 more stable and reusable in the aerobic oxidation of alcohols.
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Polymer Chemistry
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2019
·Vol. 10
·期 17
·2126-2133
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IF 4.76
Jinfeng Shi,Na Zhao,Shuang Xia,Shaofeng Liu,Zhibo Li
Polysiloxanes containing phenyl functional groups are a class of promising polymer materials with enhanced low-temperature flexibility, high-temperature stability and great damping properties. In this context, organic cyclic trimeric phosphazene bases (CTPBs) have been proved to be highly efficient for the ring-opening polymerization (ROP) of octamethylcyclotetrasiloxane (D4) and the copolymerization of D4 with octaphenylcyclotetrasiloxane (P4) under mild conditions. The polymerizations are fast and the resulting polymers have high molecular weights (Mn up to 1353 kg mol−1). The molecular structures of the obtained copolysiloxanes were characterized by 1H NMR and 29Si NMR, which demonstrate that as high as 64 mol% diphenyl siloxane units can be incorporated within the copolysiloxane chain. Remarkably, copolysiloxanes with different contents of the diphenyl siloxane group are found free of T-branches and Q-branches based on the 29Si NMR analysis, indicating a good controlled ROP by the current organocatalytic system. DSC analysis shows no crystallization exotherm or melting endotherm in the range of −70 °C to 50 °C for all the copolysiloxanes, confirming that incorporation of diphenyl groups successfully suppresses the undesirable crystallization of polydimethylsiloxane. Moreover, the thermal stability of copolysiloxanes was evaluated by TGA, showing dramatically enhanced thermal stability with the increment of the diphenyl siloxane content.
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RSC Advances
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2019
·Vol. 9
·期 28
·15694-15702
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IF 3.049
Lijing Nan,Jiao Li,Wanjun Jin,Ming Wei,Mengjun Tang,Chengjian Wang,Guiping Gong,Linjuan Huang,Ying Zhang,Zhongfu Wang
Mass spectrometry (MS) analysis combined with stable isotopic labeling is of great importance for quantitatively profiling abnormal sialylated O-glycans associated with disease development, but technically hindered by the poor releasing efficiency of O-glycans from glycoprotein or the labile nature of sialic acid residues at glycans. Herein, we developed an isotopic precursor based metabolic amplification and labeling (IPMAL) technique for relative quantitative profiling of the repertoire O-glycans between normal and tumor cells by ESI-MS. Two groups of cells were incubated with peracetylated benzyl-α-N-acetylgalactosamine (Ac3GalNAc-α-Bnd0) or a heavy labeled peracetylated benzyl-α-N-acetylgalactosamine (Ac3GalNAc-α-Bnd5) precursor respectively to amplify the repertoire of O-glycans as Bnd0/d5-O-glycans which could achieve the quantitative O-glycome analysis by ESI-MS after derivatization. The established method demonstrates desirable feasibility, accuracy (relative error (RE) ≤ 4.20%), reproducibility (coefficient of variation (CV) ≤ 7.61%, n = 3) and good quantitation linearity (R2 > 0.99, n = 3) for five Bn-O-glycans with 2 orders of magnitude. Finally, the method has been successfully applied to quantitative analysis of the repertoire O-glycome changes between normal human liver cell line L02 and human hepatoma cell line SMMC-7721. Moreover, the α-2,3/2,6 sialic acid isomers of Bn-O-glycans from these two cells have been further quantitatively distinguished when involved a sialic acid specific derivatization procedure.
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RSC Advances
·
2019
·Vol. 9
·期 14
·7833-7841
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IF 3.049
Lukai Wang,Junzong Feng,Yonggang Jiang,Liangjun Li,Jian Feng
The traditional SiO2 aerogels are difficult to apply in the fields of energy storage and heat insulation due to their poor mechanical properties. In order to deal with this issue, the polyvinylpolymethylsiloxane aerogel (PVPMSA) materials with fine mechanical flexibility and excellent thermal insulation properties are suitable substitutions. In this paper, the double cross-linking organic–inorganic hybrid PVPMSAs were prepared through the processes of free radical polymerization and hydrolytic polycondensation. The internal silica network reinforced with aliphatic hydrocarbons has significantly improved the mechanical properties and acquired a high specific surface area, reaching up to 1218 m2 g−1. Furthermore, the thermal conductivity of monolithic PVPMSAs has been investigated by changing the density and environmental conditions. Results show that PVPMSAs at 25 °C in 5 Pa have a thermal conductivity as low as 14.69 mW m−1 K−1, and the solid thermal conductivity shows a flat growth with the increase of density. Meanwhile, the nanosize pores could significantly inhibit the heat transfer of gas. As for the radiative thermal conductivity, it is greatly affected by temperature. All these results obtained from this paper would help us to design thermal insulators reasonably.
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Nanoscale
·
2019
·Vol. 11
·期 31
·14654-14667
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IF 6.97
Binbin Ding,Shuai Shao,Haihua Xiao,Chunqiang Sun,Xuechao Cai,Fan Jiang,Xueyan Zhao,Ping'an Ma,Jun Lin
The limited light penetration depth and tumor hypoxia are two natural shortcomings of photodynamic therapy (PDT). Overcoming these two issues within a single system is still a great challenge. Herein, photosensitizer (PS)-loaded and PEG-modified MnFe2O4-decorated large-pore mesoporous silica-coated β-NaYF4:20%Yb,2%Er@β-NaYF4 upconversion nanoparticles (UCMnFe-PS-PEG) as excellent PDT agents are successfully prepared for NIR light-mediated and O2 self-sufficient PDT. The large mesoporous structure observably increases PS loading efficiency (11.33 wt%) and the green luminescence from upconversion nanoparticles activated by NIR is able to activate PSs to generate ROS effectively. In addition, sub-10 nm MnFe2O4 nanoparticles work as a Fenton catalyst to generate O2in situ. In vivo experiments further prove that UCMnFe-PS-PEG not only provides magnetic guidance to the tumor, but also overcomes tumor hypoxia and dramatically enhances PDT efficiency. Furthermore, in vivo MR and UCL imaging are performed for accurate cancer therapy. We believe that the successful construction of the multifunctional UCMnFe-PS-PEG provides more revelations for developing advanced nano-drug systems for cancer therapy.
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JOURNAL OF FOOD SCIENCE AND TECHNOLOGY-MYSORE
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2019
·Vol. 56
·期 9
·4009-4015
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IF 1.85
Qin Hao,Li Bao-cai,Dai Wei-feng,Xiang Cheng,Qin Yi,Jiao Shi-yun,Zhang Mi
Volatiles have been regarded as active substances in many foods, whose chemicals can be analyzed by GC–MS qualitatively and quantitatively. However, the activities of volatiles are often studied as a whole, and it has no an effective method to determine that which molecule is active in volatiles by far. In order to identify the antioxidant molecules in volatiles, a rapid determination method was developed by GC–FID/MS combined with DPPH radical reaction in this study. Three antioxidant molecules were identified and validated among 20 components in rose tea infusion. Their activity validation and the methodological evaluation indicated this method could be used for distinguishing antioxidant molecules in volatiles rapidly and effectively.
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