JOURNAL OF HAZARDOUS MATERIALS
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2014
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IF 4.331
Jinfeng Zhang,Yingfei Hu,Xiaoliang Jiang,Shifu Chen,Sugang Meng,Xianliang Fu
A direct Z-scheme photocatalyst Bi 2 O 3 /g-C 3 N 4 was prepared by ball milling and heat treatment methods. The photocatalyst was characterized by X-ray powder diffraction (XRD), UV–vis diffuse reflection spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface areas, photoluminescence technique (PL), and electron spin resonance (ESR) technology. The photocatalytic activity was evaluated by degradation of methylene blue (MB) and rhodamine B (RhB). The results showed that Bi 2 O 3 /g-C 3 N 4 exhibited a much higher photocatalytic activity than pure g-C 3 N 4 under visible light illumination. The rate constants of MB and RhB degradation for Bi 2 O 3 (1.0 wt.%)/g-C 3 N 4 are about 3.4 and 5 times that of pure g-C 3 N 4 , respectively. The migration of photogenerated carriers adopts a Z-scheme mechanism. The photoexcited electrons in the CB of Bi 2 O 3 and photogenerated holes in the VB of g-C 3 N 4 are quickly combined, so the photoexcited electrons in the CB of g-C 3 N 4 and holes in the VB of Bi 2 O 3 participate in reduction and oxidation reactions, respectively. O 2 − , OH and h + are the major reactive species for the Bi 2 O 3 /g-C 3 N 4 photocatalytic system.
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ANALYTICAL BIOCHEMISTRY
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2014
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IF 2.305
Hui Liu,Yong-Sheng Wang,Jia-Cheng Wang,Jin-Hua Xue,Bin Zhou,Hui Zhao,Shan-Du Liu,Xian Tang,Si-Han Chen,Ming-Hui Li,Jin-Xiu Cao
A highly sensitive, low-cost colorimetric aptasensor was developed for the determination of 8-hydroxy-2′-deoxyguanosine (8-OHdG) in human urine. The method is based on a conformational switching of the 8-OHdG aptamer to form a G-quadruplex structure in the presence of 8-OHdG. The resulting G-quadruplex assembles into a peroxidase-like DNAzyme with hemin , which effectively catalyzes the oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS 2− ) by H 2 O 2 to ABTS + , resulting in an increase in the absorption signal at 416 nm along with a color change of the solution. The response signals linearly correlated with the concentration of 8-OHdG, ranging from 466 pM to 247 nM with a detection limit of 141 pM. The relative standard deviation and the recovery were 1.97–3.47% ( n = 11) and 98.8–100.2%, respectively. The proposed method avoids the label and derivatization steps in common methods and allows direct analysis of the samples by the naked eye without costly instruments, which is reliable, inexpensive, and sensitive.
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PHARMACEUTICAL RESEARCH
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2013
·Vol. 31
·期 2
·291-304
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IF 4.742
Yang Xiao-Li,Luo Yan-Ling,Xu Feng,Chen Ya-Shao
Purpose Block copolymer micelles are extensively used as drug controlled release carriers, showing promising application prospects. The comb or brush copolymers are especially of great interest, whose densely-grafted side chains may be important for tuning the physicochemical properties and conformation in selective solvents, even in vitro drug release. The purpose of this work was to synthesize novel block copolymer combs via atom transfer radical polymerization, to evaluate its physicochemical features in solution, to improve drug release behavior and to enhance the bioavailablity, and to decrease cytotoxicity. Methods The physicochemical properties of the copolymer micelles were examined by modulating the composition and the molecular weights of the building blocks. A dialysis method was used to load hydrophobic camptothecin (CPT), and the CPT release and stability were detected by UV–vis spectroscopy and high-performance liquid chromatography, and the cytotoxicity was evaluated by MTT assays. Results The copolymers could self-assemble into well-defined spherical core-shell micelle aggregates in aqueous solution, and showed thermo-induced micellization behavior, and the critical micelle concentration was 2.96–27.64 mg L −1 . The micelles were narrow-size-distribution, with hydrodynamic diameters about 128–193 nm, depending on the chain length of methoxy polyethylene glycol (mPEG) blocks and poly(N-isopropylacrylamide) (PNIPAM) graft chains or/and compositional ratios of mPEG to PNIPAM. The copolymer micelles could stably and effectively load CPT but avoid toxicity and side-effects, and exhibited thermo-dependent controlled and targeted drug release behavior. Conclusions The copolymer micelles were safe, stable and effective, and could potentially be employed as CPT controlled release carriers.
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APPLIED CATALYSIS A-GENERAL
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2015
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IF 3.942
Hong Liu,Zhengzheng Xu,Zhe Zhang,Dan Ao
A series of novel visible light-responsive Mn 0.8 Cd 0.2 S/g-C 3 N 4 hybrid materials with different g-C 3 N 4 contents were synthesized via a facile hydrothermal method. The obtained Mn 0.8 Cd 0.2 S/g-C 3 N 4 composites displayed highly efficient photocatalytic activities for H 2 evolution from aqueous solutions containing sacrificial reagents (Na 2 S and Na 2 SO 3 ) under visible light ( λ > 420 nm) even without noble metal co-catalysts. The highest H 2 evolution rate of 4.0 mmol h −1 g −1 (with an apparent quantum efficiency of 4.1% at 420 nm) was achieved on the Mn 0.8 Cd 0.2 S/g-C 3 N 4 (10 wt%) sample, which was about 3.40 times higher than that of pure Mn 0.8 Cd 0.2 S. The enhanced photocatalytic activity of Mn 0.8 Cd 0.2 S/g-C 3 N 4 composites should be attributed to the well-matched band structure and intimate contact interfaces between Mn 0.8 Cd 0.2 S and g-C 3 N 4 , which led to the effective transfer and separation of the photogenerated charge carriers. In addition, the Mn 0.8 Cd 0.2 S/g-C 3 N 4 photocatalysts showed good stability during the photocatalytic water splitting to hydrogen under visible light. A possible mechanism of the enhanced photocatalytic activity of Mn 0.8 Cd 0.2 S/g-C 3 N 4 was also proposed.
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ADVANCED FUNCTIONAL MATERIALS
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2017
·Vol. 27
·期 22
·1700653
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IF 12.124
Jia Yan,Marco-Tulio F. Rodrigues,Zhilong Song,Hongping Li,Hui Xu,Huan Liu,Jingjie Wu,Yuanguo Xu,Yanhua Song,Yang Liu,Peng Yu,Wei Yang,Robert Vajtai,Huaming Li,Shouqi Yuan,Pulickel M. Ajayan
Many unique properties arise when the 3D stacking of layered materials is disrupted, originating nanostructures. Stabilization, and further reorganization of these individual layers into complex 3D structures, can be essential to allow these properties to persist in macroscopic systems. It is demonstrated that a simple hydrothermal process, assisted by ionic liquids (ILs), can convert bulk g-C 3 N 4 into a stable hydrogel. The gelation occurs through delamination of the layered structure, driven by particular interactions between the IL and the carbon nitride sheets, forming an amphiphilic foam-like network. This study employs spectroscopic and computational tools to unravel the gelation mechanism, and provides a rational approach toward the stabilization of 2D materials in hydrogels. The solution-processable hydrogels can also be used as building blocks of complex devices. Chemiresistive gas sensors employing g-C 3 N 4 3D hydrogels exhibit superior response at room temperature, enabling effective gas sensing under low power conditions.
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Materials Science & Engineering C-Materials for Biological Applications
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2017
·
IF 4.164
Buguang Zhou,Min He,Ping Wang,Haitian Fu,Yuanyuan Yu,Qiang Wang,Xuerong Fan
Silk fibroin (SF) as a bioactive protein can offer growth substrates for hydroxyapatite (HAp) deposition. In the current work, graft copolymerization of acrylic acid (AA) onto fibroin chains was carried out using hydrogen peroxide-horseradish peroxidase (H 2 O 2 -HRP) catalytic system, SF-g-polyacrylic acid (PAA) membranes was prepared subsequently, followed by in situ biomimetic mineralization in the Ca/P solutions, aiming at promoting the deposition of HAp and endowing the fibroin-based biocomposite with enhanced bioactivity. Meanwhile, p -hydroxyphenylacetamide (PHAD) and methyl acrylate (MA), as the model compounds of tyrosine residues in SF and vinyl monomer were used to disclose the mechanism of graft copolymerization. The data from FTIR and SEC chromatograms indicated that vinyl monomer was successfully graft copolymerized with SF during H 2 O 2 -HRP treatment. According to the results of XRD, SEM patterns and EDS-Mapping, mineral phases on the surfaces of SF-g-PAA membranes were detected after different cycles of biomimetic mineralization, and the mechanical property of SF-g-PAA/HAp membrane was noticeably improved. Cell viability and adhesion assays revealed that the composite of SF-g-PAA/HAp exhibited acceptable biocompatibility and outstanding adhesion property. The present work provides a novel method for preparation of the fibroin-based biomaterial for bone tissue engineering.
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RSC Advances
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2016
·Vol. 6
·期 67
·62186-62192
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IF 3.289
Jianjian Cai,Shouyong Zhou,Yijiang Zhao,Ailian Xue,Yan Zhang,Meisheng Li,Weihong Xing
The hydrophilicity of a thermo-responsive PVDF/palygorskite-g-PNIPAAM hybrid ultrafiltration membrane was enhanced via surface segregation induced by coagulation bath temperature (CBT). The N1s content of the hybrid ultrafiltration membranes prepared at 5 and 20 °C is 1.77% and 1.02%, respectively while that of the membrane prepared at 40 °C is just 0.73%. This indicated that the PNIPAAM chains could be dragged to the membrane surfaces or pores via surface segregation induced by temperature. This resulted in higher hydrophilicity and permeability as well as thermo-responsiveness for membranes prepared at lower temperatures. The initial water contact angle of the PVDF/palygorskite-g-PNIPAAM hybrid ultrafiltration membrane prepared at 5 and 20 °C is 75.2° and 75°, respectively, which is about 6° lower than the one prepared at 40 °C. A higher pure water flux (PWF) of about 366 L m−2 h−1 at 40 °C was obtained for the hybrid membrane prepared at 5 °C while the one prepared at 40 °C only reached 274 L m−2 h−1. Meanwhile, membranes prepared at low temperature exhibited fewer macrovoids, lower membrane thickness and larger elongation.
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Nano Energy
·
2016
·
IF 11.553
Lihua Yao,Ding Wei,Yuanman Ni,Dongpeng Yan,Changwen Hu
The construction of new semiconductor photocatalysts toward high-efficiency splitting water has played an important role in developing sustainable and clean hydrogen energy . In this work, new type of micro/nano-sized hybrids were synthesized based on the assembly of 0D Cd 0.5 Zn 0.5 S quantum dots (QDs, size: ca. 5 nm) onto 2D graphitic carbon nitride ( g -C 3 N 4 ) ultrathin microribbons (thickness: ca. 4 nm) via an in-situ growth hydrothermal method . The Cd 0.5 Zn 0.5 S 32 wt%@C 3 N 4 composite exhibits the highest visible-light-driven H 2 -generation rate of 33.41 mmol h −1 g −1 without any noble-metal as cocatalyst , and the apparent quantum efficiency is 46.65% at 450 nm. Such H 2 -generation rate is higher than the pristine g -C 3 N 4 and Cd 0.5 Zn 0.5 S by a factor of 27.39 and 9.18 respectively, which is significantly enhanced compared with most as-reported noble-metal-free semiconductor catalysts to date. In addition, compared with the pristine Cd 0.5 Zn 0.5 S, the photocatalytical stability of Cd 0.5 Zn 0.5 S QDs@C 3 N 4 is highly improved. The enhanced H 2 -generation performance can be attributed to the well-matched energy level and strong electronic coupling between two components at the g- C 3 N 4 interface as well as enhanced visible-light absorption. The uniform dispersion of Cd 0.5 Zn 0.5 S QDs onto the g -C 3 N 4 ultrathin microribbons also facilitates the depression of electron-hole recombination from potential aggregation of Cd 0.5 Zn 0.5 S. Therefore, this work supplies an effective way to obtain promising 2D micro/nanostructures for high-efficiency visible light-induced H 2 -generation.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2017
·
IF 3.133
Xue Yu,Peiwen Wu,Caixia Qi,Junjie Shi,Lijuan Feng,Chunhu Li,Liang Wang
Tremendous demands for photocatalysts with high chemical activity and stability, low cost and capability of response to visible-light have stimulated intensive research on developing versatile materials with special photocatalytic applications. Here we report a novel g-C 3 N 4 /BiOBr-RGO aerogel ternary-component heterojunction photocatalyst for degradation of RhB under visible light irradiation. As a result of synergistic effect of the g-C 3 N 4 , BiOBr and RGO, the hybrid photocatalysts exhibit better activity than the single component catalysts (pure g-C 3 N 4 , BiOBr) and bi-component catalysts (g-C 3 N 4 /BiOBr) in the same time period (60 min). The enhanced photocatalytic performance originates from a novel nanoarchitecture in which BiOBr exposed more active plane and RGO worked as a conductive support further improved the photogenerated charge separation. Moreover, due to the 3D structure of RGO after reaction the photocatalysts can be easily removed from the treated solution and reused, which opens up a way for the recycling applications of catalysts in aqueous reaction systems.
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APPLIED SURFACE SCIENCE
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2017
·
IF 3.387
Ruirui Hao,Guohong Wang,Chuanjia Jiang,Hua Tang,Qingchuan Xu
Semiconductor-based photocatalysis is a promising method for degradation of environmental pollutants, but the activity of most widely used photocatalysts such as titania (TiO 2 ) is still unsatisfactory under visible light. Herein, we synthesized a highly efficient visible-light-responsive heterojunction catalysts based on graphitic carbon nitride (g-C 3 N 4 ) and TiO 2 . The g-C 3 N 4 /TiO 2 heterojunction composites with high specific surface area were prepared via in situ hydrothermal synthesis followed by calcination , using titanium tetrachloride (TiCl 4 ) and melamine as precursors. Interesting, HCl from the hydrolysis of TiCl 4 served as the proton source to acidify the melamine. The g-C 3 N 4 /TiO 2 heterojunction composites exhibited higher photocatalytic performance for decomposition of Rhodamine B (RhB) than pure g-C 3 N 4 or TiO 2 under visible light irradiation. The high activity can be ascribed to the high specific surface area (up to 115.6 m 2 g −1 ) of the g-C 3 N 4 /TiO 2 composites and a synergistic heterojunction structure between TiO 2 and g-C 3 N 4 . Moreover, the photocatalytic performances of the g-C 3 N 4 /TiO 2 composites rely on the content of melamine in the synthesis precursors: with an optimum melamine content (3 g for 0.5 mL of TiCl 4 ), the sample showed the highest photocatalytic performance, which is superior to pure TiO 2 and g-C 3 N 4 by a factor of 18.7 and 3.5, respectively. Active species trapping experiments revealed that superoxide radicals and photogenerated holes played crucial roles in the photocatalytic reactions. The results will provide new ideas for the smart design and development of g-C 3 N 4 -based highly active photocatalysts with ultrahigh specific surface area for environmental and energy applications.
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ChemCatChem
·
2016
·Vol. 8
·期 22
·3527-3535
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IF 4.724
Feng-Yun Su,Cheng-Qun Xu,Yu-Xiang Yu,Wei-De Zhang
Graphical Carbon self-doped g-C 3 N 4 nanosheets were synthesized in a simple way by a one-step calcination of a ternary supramolecular network of cyanuric acid, ethylene glycol (EG), and melamine. Carbon doping resulted in a distorted framework and induced the activation of n–π* electronic transitions of the C-g-C 3 N 4 nanosheets. The obtained C-g-C 3 N 4 displayed high activity for photocatalytic H 2 evolution owing to the extended light harvesting and faster separation of photogenerated electrons and holes. This paper reports a facile one-pot synthesis strategy to prepare carbon self-doped g-C 3 N 4 (C-g-C 3 N 4 ) nanosheets by using supramolecular networks consisting of cyanuric acid, ethylene glycol (EG), and melamine (CEM) bonded through hydrogen bonding as the thermal polycondensation precursor, in which EG serves as a solvent for cyanuric acid and melamine, and as a source of the doped carbon simultaneously. The threedimensional structure of CEM resulted in the distortion of C-g-C 3 N 4 , which is capable of motivating the n–π* electronic transition involving the N lone pairs to give an additional absorption region from 450 to 600 nm. The hydrogen evolution rate of C-g-C 3 N 4 reaches 73.09 μmol h −1 , which is about 15 times of that over the g-C 3 N 4 obtained from direct thermal polycondensation of melamine owing to its extended light harvesting and faster separation of photogenerated electrons and holes.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2016
·
IF 8.328
Yanyang Shang,Xi Chen,Wenwen Liu,Pengfei Tan,Haoyun Chen,Laidi Wu,Cheng Ma,Xiang Xiong,Jun Pan
A facile microemulsion-assisted co-precipitation method was carried out to synthesize nano-sized Ag 2 CrO 4 highly dispersed on the surface of porous g-C 3 N 4 as high-efficiency visible-light-driven composite photocatalysts for the first time. The structure and morphology of the composites were systematically characterized by various techniques. Compared with Ag 2 CrO 4 and g-C 3 N 4 , g-C 3 N 4 /Ag 2 CrO 4 composites showed a dramatically increased photocatalytic activity in degradation of rhodamine B (RhB) and methylene blue (MB). The optimum mass ratio of the Ag 2 CrO 4 to g-C 3 N 4 was about 30 wt%, the degradation rate of which were 6.1 (7.9) and 9.7 (15.2) times higher than pure Ag 2 CrO 4 and g-C 3 N 4 in RhB (MB) degradation, respectively. The excellent photocatalytic activity and stability mainly benefited from the synergistic effect including smaller Ag 2 CrO 4 particle size, high specific surface area of the composites and matched band potentials which not only promoted the separation of photon-generated charge carriers, but also inhibited the photocorrosion of Ag 2 CrO 4 . Further study revealed that the photocatalytic mechanism followed a Z-scheme which provided an efficient transfer pathway for charge carriers meanwhile endowed the composites with strong oxidation and reduction ability. Hence the porous g-C 3 N 4 /Ag 2 CrO 4 composites are potential in environmental purification.
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