CARBON
·
2020
·
IF 8.821
Jinqiao Li,Xiaoteng Liu,Huinan Che,Chunbo Liu,Chunxiang Li
Realizing the efficient utilization of photogenerated carriers is a pivotal process to access the efficient transformation of light energy . Herein, we firstly practice a facile template method to synthesize O-doped crystalline/none-crystalline g-C 3 N 4 embedded nano-homojunction photocatalysts (CMCCN-x). This nano-homojunction makes the crystalline phase sufficiently contact with amorphous phase and further facilitates the photoinduced electron transformation. Therefore, the best performance catalyst CMCCN-5 well integrates the advantages of crystal g-C 3 N 4 and amorphous g-C 3 N 4 , which exhibits an excellent photogenerated carrier separation ability and abundant photocatalytic hydrogen evolution reaction activity sites. Excellent performance in the separation and use of photogenic carriers endows CMCCN-5 with efficient utilization of photogenerated carriers. Although there is a limited light absorption range (<460 nm), the photocatalytic hydrogen evolution rate of CMCCN-5 is up to 203.66 μmol h −1 under the visible light irradiation, about 86 times higher than pristine g-C 3 N 4 . The AQY numbers of CMCCN-5 at 420 nm and 450 nm are up to 26.9% and 14.0%, respectively. Thus, the significant effectiveness is forcefully proved for the facile construction of O-doped g-C 3 N 4 crystalline/none-crystalline nano-homojunction.
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JOURNAL OF THE CHINESE CHEMICAL SOCIETY
·
2020
·Vol. 68
·期 4
·582-591
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IF 1.554
Changzhou Chen,Peng Liu,Haihong Xia,Minghao Zhou,Jianchun Jiang
There is an urgent need to develop a selective hydrogenolysis of C aryl -O bonds in lignin to produce valued-added chemicals and fuels. Recently, hydrogen has been used in the hydrogenation reaction, which hides inevitable danger and is not economical. Therefore, isopropanol, as a hydrogen-donor solvent, is employed for aryl ether hydrogenolysis in lignin models over nickel supported on a carbon nanotube (CNT). Except for aromatic ether (4-O-5), the Ni/CNT catalyst is also found to be suitable for alkyl-aryl ether (α-O-4 and β-O-4) cleavage in control experiments. The physicochemical characterizations were carried out by means of H 2 -temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. The catalyst can be magnetically recovered and efficiently reused for five consecutive recycling tests in the transfer hydrogenation of aromatic ethers. A mechanism study indicated that the hydrogenolysis cleavage of the ether bond is the first step in the reaction process, and hydrogenation of aromatic rings is only a successive step in which phenol and benzene are intermediate states and are then further hydrogenated. Furthermore, it has been demonstrated that aryl groups play an important role in the hydrogenation of phenol in the competitive catalytic hydrogenation reaction of phenol.
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JOURNAL OF MATERIALS SCIENCE
·
2020
·Vol. 55
·期 22
·9425-9435
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IF 3.553
Guo Yufei,Wang Li,Xu Lijuan,Peng Canwei,Song Yonghai
A flexible ascorbic acid (AA)-imprinted poly(o-phenylenediamine) (ploy(o-PD))/zeolite imidazole frameworks-67 (ZIF-67)/carbon cloth (CC) electrode was prepared for electrochemical sensing AA. The flexible AA-imprinted poly(o-PD)/ZIF-67/CC electrode was prepared by growing ZIF-67 on flexible CC, electropolymerization of o-PD with AA on ZIF-67/CC and eluting template molecules AA. The results showed that the spherical ZIF-67 crystals were arranged evenly and firmly on the fibers of CC surface. The diameter of spherical ZIF-67 crystals was approximately 500–600 nm, and the spherical ZIF-67 crystals catalyzed the oxidation of AA well. A layer of poly(o-PD) with AA-imprinted pores was covered on the ZIF-67/CC electrode, so the AA-imprinted poly(o-PD)/ZIF-67/CC electrode exhibited better selectivity toward AA detection and good stability. The molecularly imprinted sensor exhibits high sensitivity, and the sensitivity could reach 959.9 μA/mM −1 cm −2 , the detection limit was 0.019 μM, and the concentration range of AA was 0.057 μM–11.4 0 mM. The AA-imprinted poly(o-PD)/ZIF-67/CC electrode also showed higher stability and repeatability. The results proved that the spherical ZIF-67 crystals were good electrode materials for electrochemical AA biosensors.
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Catalysts
·
2020
·Vol. 10
·期 5
·485
·
IF 3.52
Ming Zhang,Zhen Song,Mengquan Guo,Xiangxiang Li,Yanjun Lin,Lihong Zhang
The effect of reduction atmospheres, H2/N2, C3H8/H2/N2, C3H8and CO, on the structure and propane direct dehydrogenation performance of PtIn/Mg(Al)O/ZnO catalyst derived from ZnO-supported PtIn-hydrotalcite was studied. The physicochemical properties of the as-prepared and used catalytic system were characterized by various characterization methods. The results show that the dehydrogenation performance, especially the stability of the PtIn/Mg(Al)O/ZnO catalyst, was significantly improved along with the change in reduction atmosphere. The highest catalytic activity (51% of propane conversion and 97% propylene selectivity), resistance toward coke deposition, and stability for more than 30 h were achieved with the H2/N2-reduced catalyst. The optimal dehydrogenation performance and coke resistance are mainly related to the high Pt dispersion and In0/In3+molar ratio, strong Pt–In interaction and small metal particle size, depending on the nature of the reduction atmospheres. The reconstruction of meixnerite favors the stability and coke resistance to some extent.Keywords:propane dehydrogenation;reduction atmosphere;coke deposition;meixnerite;PtIn/Mg(Al)O/ZnO
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JOURNAL OF EXPERIMENTAL BOTANY
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2020
·Vol. 71
·期 10
·3066-3079
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IF 5.908
Liu Xiaojuan,Zhao Chenning,Gong Qin,Wang Yue,Cao Jinping,Li Xian,Grierson Donald,Sun Chongde
Polymethoxylated flavones (PMFs), which accumulate exclusively in fruit peel of citrus, play important physiological and pharmacological roles but the genetic basis for the methylation of flavonoids has not been fully elucidated in citrus. Here we characterize a caffeoyl-CoA O-methyltransferase-like enzyme, designated CrOMT1. The expression pattern of CrOMT1 was highly correlated with the concentration of the three major PMFs in two different citrus fruit tissues during fruit maturation. Exposure of fruit to UV-B radiation sharply increased the level of CrOMT1 transcripts and also led to the accumulation of three PMFs. The potential role of CrOMT1 was studied by testing the catalytic activity of recombinant CrOMT1 with numerous possible substrates in vitro. The enzyme could most efficiently methylate flavones with neighboring hydroxy moieties, with high catalytic efficiencies found with 6-OH- and 8-OH-containing compounds, preferences that correspond precisely with the essential methylation sites involved in the synthesis of the three naturally occurring PMFs in Citrus reticulata. This indicates that CrOMT1 is capable of in vitro methylation reactions required to synthesize PMFs in vivo. Furthermore, transient overexpression of CrOMT1 increased levels of the three major PMFs in fruit, indicating that CrOMT1 is likely to play an essential role in the biosynthesis of PMFs in citrus.
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CHEMICAL ENGINEERING JOURNAL
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2020
·
IF 10.652
Zhuang Wang,Asad Mahmood,Xiaofeng Xie,Xiao Wang,Hanxun Qiu,Jing Sun
For the oxide-based photocatalysts, polyoxylic acid modification can affect their adsorption/desorption properties and further regulate photocatalytic reaction pathway, which is crucial for enhancing photocatalytic activity and selectivity. Herein, phosphoric acid modified TiO 2 was synthesized by a facile impregnation-calcination method for photocatalytic degradation of gaseous o-xylene. According to FTIR, XPS, and EDS analysis, phosphoric acid was anchored on the surface of TiO 2 successfully. The surface P atomic percentages for PT1 was 2.45%. The as-prepared phosphoric acid modified TiO 2 (PTx) had a photocatalytic performance superior to that of commercial TiO 2 and unmodified TiO 2 (PT0), with increasing by 2.2 times at most. Interestingly, the phosphoric acid molecules strongly adsorbed on anatase TiO 2 surface by forming H–O 2C and =O–Ti 5C chemical bonds according to the first principle calculations, which changed TiO 2 surface properties (specific surface area and surface negative electrostatic field) and further improved adsorption and charge carrier separation and transfer, thus improving the photocatalytic activity. Additionally, according to the intermediates results, the relative abundance of intermediates shows obvious difference. Acetone was detected as the most abundant intermediates during o-xylene degradation for PT0, whereas that was o-methyl benzaldehyde for PT1, which could be ascribed to the difference of surface adsorption configuration of o-xylene. According to the temperature-programmed desorption (TPD) results, the surface modified by phosphoric acid could change the o-xylene adsorption configuration to favor its methyl oxidation (standing configuration), whereas the unmodified surface could be more favorable to the benzene ring-open reaction (lying configuration). This work will deepen the understanding of the relevance of surface modification and surface photocatalytic reaction, which also provides a feasible strategy to improve photocatalytic selectivity.
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ANALYTICAL AND BIOANALYTICAL CHEMISTRY
·
2020
·Vol. 412
·期 11
·2545-2550
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IF 3.637
Yu Haili,Dong Faqin,Chen Jiahui,Li Bowen
Nitric oxide (NO) plays an important role in the generation of smog and ozone. Although great efforts have been made to determine NO by using o-phenylenediamine (OPD)-based fluorescent probes, more simple and reliable colorimetric assays for detection of NO are extremely scarce because a single OPD structure cannot produce enough optical absorption for chromogenesis. In this study, we report an innovative two-in-one visual colorimetric methodology. Commercially available 3,3′-diaminobenzidine (DAB) with two OPD structures in a single molecule is selected as the colorimetric probe, and it reacts with NO via diazo-coupling reaction to generate 1H,3’H-[5,5′]bibenzotriazolyl because of the increase of conjugated double bonds, accompanying a distinct color change from colorless to brownish yellow. This two-in-one colorimetric assay can determine NO at a concentration as low as 3 ppm by the naked eye and 40 ppb by UV-vis spectrometry, which is the lowest limit of detection (LOD) among reported colorimetric assays for NO. Moreover, the present two-in-one visual colorimetric assay also has good selectivity toward NO over other common potential gas interferents such as CO 2 , NO 2 , NH 3 , N 2 , O 2 , and SO 2 . This present study provides a new insight for the design and development of assays for NO.
Graphical abstract
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POLYMERS FOR ADVANCED TECHNOLOGIES
·
2020
·Vol. 31
·期 10
·2127-2135
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IF 2.578
Wei Zhang,Kaikai Wang,Xiaodan Hu,Xiaohong Zhang,Shuquan Chang,Haiqian Zhang
The irradiation of tumors in radiotherapy requires accurate 3D dosimetry. The Fricke 3D dosimeters, which were considered to be high potential of application in 3D dosimetry, suffer from a reduced temporal integrity of dose distribution caused by Fe 3+ ions diffusion. To overcome the drawback, we firstly synthesized a kind of amphiphilic molecules with critical micelle concentration of 0.45 g/L and hydrophile-lipophile balance value of 10, then prepared multiple emulsions by self-assembling those molecules in Fricke solution under liquid paraffin, and finally obtained Fricke hydrogel embedded with the multiple emulsions. The diffusion coefficient of Fe 3+ ions in the embedded Fricke hydrogel was measured to be 0.17 mm 2 /h. The hydrogel dosimeter exhibits considerable potential for use in dose verification applications.
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ACS Sustainable Chemistry & Engineering
·
2021
·
IF 8.198
Xiangchen Kong,Chao Liu,Ming Lei,Feng Gong,Yue Han,Yuyang Fan,Ming Li,Rui Xiao
The fundamental understanding of the catalytic performance of copper-based catalysts for lignin hydroconversion is delayed compared with the empirical optimization of the catalyst preparation. Herein, we investigate the interplay between the lignin-abundant oxygen-containing functional groups and Cu active species via the catalytic β-O-4 lignin linkage hydrogenolysis. Catalyst performance data and elemental spectra characterizing the catalyst demonstrate the dominance of Cu0 in the catalysis. Remarkably, Cα–OH and Cα═O in the aliphatic chain play critical roles in this process, without which the linkage cannot be broken. These groups markedly accelerate the linkage cleavage by decreasing both the chemisorption energy between Cβ–O and Cu0 and the bond dissociation energy of the linkage. On the contrary, the methoxyl groups attached to the aromatic rings hinder the bond cleavage as a result of the steric effect. Such hindrance is significantly affected by the amount and position of the methoxyl groups. The results of this work highlight the importance of the unique structures of lignin in its reductive depolymerization catalyzed by copper-based catalysts, which appear to offer an opportunity for tailoring efficient copper-based catalysts for lignin hydrogenolysis.
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APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Sleshi Fentie Tadesse,Dong-Hau Kuo,Worku Lakew Kebede,Girma Sisay Wolde
Developing low-cost and visible-light-driven metal oxide and sulfide-based photocatalysts for the degradation of organic dyes has been a major area of research to mitigate environmental pollution. In this study, a low-cost and facile precipitation method at low temperature of 95 °C was used to synthesize visible-light-driven Nd 2 O 3 /Mo(S,O) 3-x ·0.34H 2 O heterojunctions (NdMoOS). The crystal structure, elemental composition, optical, and electrical properties of as-prepared materials were investigated using various analytical techniques. Organic dyes of methyl orange (MO), Rhodamine B (RhB), and Methylene blue (MB) were selected as model organic pollutants to evaluate the photocatalytic efficiency of as-synthesized materials under visible light irradiation. 20 mol% NdMoOS nanocomposite showed excellent degradation efficiency and it decomposed 98.8%, 99.9%, and 99.8% of MO, RhB, and MB after 120 min, 90 min, and 90 min visible light irradiation, respectively. HPLC-MS analysis further confirms the complete removal of dyes. The formation of heterojunction, high charge separation, and low recombination rate of photoinduced e - -h + pairs can contribute to the enhanced photocatalytic activity. Superoxide radicals (O 2–• ), hydroxyl radicals (HO • ), and holes (h + ) were identified as major oxidative species involved in the photocatalytic degradation mechanisms of MO, RhB, and MB dyes.
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FOOD HYDROCOLLOIDS
·
2021
·
IF 9.147
Yilan Wu,Xingzhong Zhang,Dan Qiu,Ying Pei,Yan Li,Bin Li,Shilin Liu
In this study, the effect of surface charge density of bacterial cellulose nanofibrils (BCNF) on the rheological characteristics of O/W Pickering emulsions was investigated by regulating the fibril charge density. BCNFs with different carboxylate group contents (0.66, 0.90 and 1.16 mmol/g dry cellulose, representing as TOBC-a, -b, and -c) were obtained by 2,2,6,6-tetramethylpiperidine-nitrogen-oxide (TEMPO) oxidation . These oxidized products were used as Pickering stabilizers to prepare O/W Pickering emulsions. Diffusing wave spectroscopy (DWS)-based microrheology was utilized to reflect the rheological features of emulsions. TOBC-a stabilized emulsion had a lower macroscopic viscosity, lower elasticity, and better fluidity. It was because a weaker fiber network was formed in the continuous phase during the ultrasonication emulsification . The influences of pH and ionic strength on the rheological properties of high-charged TOBC-c stabilized emulsions were also investigated. The emulsion prepared at pH 3.0 exhibited the highest viscosity. It was probably because the inter-fibrils electrostatic repulsion was weakened by the addition of HCl, and the hydrogen bonding interaction became dominant due to the protonation of carbohydrate group. At pH 11, the emulsion viscosity was lowest, which was resulted from the destruction of the intra-fibrils hydrogen bonds. With the NaCl concentration increased, the emulsion viscosity and elasticity increased. It was induced by the fact that the charge shielding effect of NaCl facilitated the formation of a tighter fibrils network in the continuous phase. These results have the potential to provide a guide for developing emulsion-based products with appropriate fluidity to broaden the practical application of emulsion.
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Analytical Methods
·
2021
·Vol. 13
·期 43
·5231-5239
·
IF 2.896
Xuejia Chen,Tingkai Xiong,Jin Xu,Yan Li,Min Zhang,Ying Liang
In this paper, a novel and stable fluorescent reagent, quinoline-2,3-dicarbaldehyde (QDA), is synthesized as a probe to detect ammonium in natural water. Ammonium reacts with QDA in the presence of SO32− and Ca2+ to form a fluorescence product, which has maximum excitation and emission wavelengths at 429 nm and 518 nm. The concentration of reagents, the reaction temperature, the reaction time, and the pH in the final solution are investigated and optimized. The interferences of typical organic nitrogen and inorganic compounds are evaluated, and results prove that most volatile amines have little or negligible effect. Under the optimized conditions, this method provides a limit of detection of 0.065 μmol L−1, a calibration range of 0.216–9 μmol L−1, and reproducibility (with a relative standard deviation) of 1.9% for 1.5 μmol L−1 ammonium. For water sample analysis, the proposed method provides comparable results to those of the conventional o-phthalaldehyde method but has longer reagent stability (42 days).
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