ChemPlusChem
·
2018
·Vol. 83
·期 11
·1038-1043
·
IF 3.205
Song Wang,Hejin Jiang,Li Zhang,Jian Jiang,Minghua Liu
Graphical Supramolecular gels formed from hemin and histidine amphiphiles were tested as artificial enzymes to catalyse the oxidation of the chiral substrate L-DOPA to L-dopachrome. The supramolecular gel made up of left-handed helices enhanced the catalytic activity of hemin effectively, and more interestingly, it exhibited enantioselectivity. Supramolecular co-assembly provides an efficient way to combine structural and functional units through noncovalent interactions and produce materials with enhanced performance. Here, using a chiral amphiphilic histidine derivative (LHC18 or DHC18) as a gelator, we have successfully co-assembled the gelator and hemin through gelation. During the co-assembly, the chiral information of the gelator was transcribed into the assemblies, and thus right- and left-handed helical ribbons from LHC18-Hemin and DHC18-Hemin co-assemblies were obtained, respectively, which were confirmed by CD spectra and SEM observations. These helical ribbons were used as artificial enzymes to catalyse the oxidation reaction of 3,4-dihydroxy-L-phenylalanine (L-DOPA). The catalytic activity of hemin in supramolecular gels can be effectively enhanced over that of free hemin. Moreover, by virtue of induced chirality, the supramolecular gels of LHC18-Hemin and DHC18-Hemin exhibited obvious enantioselective activity. This work provides a way to combine chirality transfer and supramolecular asymmetric catalysis.
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Journal of Materials Chemistry A
·
2018
·Vol. 6
·期 36
·17730-17739
·
IF 9.931
Rui Zhang,Xiangxia Jing,Yanting Chu,Lei Wang,Wenjun Kang,Denghu Wei,Haibo Li,Shenglin Xiong
A novel monolithic carbon sponge is prepared by a ZnCl2-assisted carbonization of commercial melamine foam (MF) at 800 °C in a N2 atmosphere. The as-prepared nitrogen/oxygen co-doped carbon sponges (NOCSs) can be directly applied as monolithic electrodes for supercapacitors without using any additives. It is found that ZnCl2 activation plays an important role in improving the supercapacitive behavior of NOCSs. Compared with the NOCS without ZnCl2 activation treatment, the optimal NOCS-1/10, obtained with a ZnCl2/MF weight ratio of 1 : 10, has the best capacitive performance due to its unique porous architecture, rich pseudocapacitance-active species, and good electron/ion transfer feature. It exhibits a high specific capacitance (242 F g−1 at a current density of 0.5 A g−1 and 325 F g−1 at a scan rate of 10 mV s−1) and good electrochemical cyclability (97% after 10 000 cycles at 5.0 A g−1). When being further assembled into an all-solid-state supercapacitor (PVA/KOH electrolyte), it can deliver an energy density of 4.33 W h kg−1 at a power density of 250 W kg−1 and 3.13 W h kg−1 at a power density of 3 kW kg−1.
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Journal of Materials Chemistry A
·
2018
·Vol. 6
·期 41
·20100-20109
·
IF 9.931
Xia Shi,Aiping Wu,Haijing Yan,Lin Zhang,Chungui Tian,Lei Wang,Honggang Fu
The rational combination of early-transition metal nitrides (ETMNs) with late-transition metals (LTMs) is a promising method for the design of highly efficient catalysts. Herein, we report the design of Co–Mo2N tubes based on a “MOFs plus MOFs” strategy for efficient electrocatalytic water splitting in 1 M KOH. The 1-D Mo-MOFs (Mo source) were prepared in large quantities by the reaction of imidazole with MoO3. ZIF-67 (Zeolitic Imidazolate Framework-67) (Co source) was then grown on the 1-D Mo-MOFs (Mo-based metal–organic frameworks) to obtain ZIF-67/Mo-MOFs by a solution-phase assembly method. The effective combination is due to the similarity of the ligands in the two MOFs. After nitriding, the ZIF-67 was converted into Co metal, and Mo-MOFs were converted into hollow Mo2N, thus giving a hollow Co–Mo2N hybrid with a Co outer layer on the Mo2N inner core. The ratio of Co and Mo in Co–Mo2N can be easily tuned to give optimized catalysts. The tests indicated that the combination of Co and Mo2N can significantly boost the HER performance of materials. At the current density of 10 mA cm−2, the overpotential (η10) on Co–Mo2N was only 76 mV, which is much lower than 296 mV for Mo2N derived from Mo-MOFs and 180 mV for Co–carbon from ZIF-67. The hybrid has also shown improved OER activity in comparison with Mo2N and Co; therefore, the Co–Mo2N can be used as both anode and cathode for an overall water-splitting cell with η10 of 1.576 V. The improved HER activity can be ascribed to the intimate contact between Co and Mo2N for optimized adsorption on reagents, the tube-like structure for easy mass transfer and the good conductivity of Mo2N, which is favourable for transmitting charge.
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CATALYSIS TODAY
·
2018
·
IF 4.667
Lingcong Li,Xiaojun Liu,Hong He,Ningqiang Zhang,Ziwen Liu,Guizhen Zhang
The MgO-doped hexagonal boron nitride (MgO-h-BN) nanomaterials were designed as a support for Palladium (Pd) catalysts for CO oxidation reaction. The catalytic properties of Pd/MgO(5)-h-BN catalyst was investigated and compared with Pd/h-BN catalyst. Transmission electron microscopy (TEM) results suggested that the PdO nanoparticles with small grain sizes (ca. 8 nm) were effectively dispersed on the surface of MgO, and the MgO were deposited on the h-BN nanosheets in the Pd/MgO(5)-h-BN catalyst. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses revealed that a small amount of Mg 2+ embedded into the B vacancies of h-BN nanosheets in the Pd/MgO(5)-h-BN catalyst. More significantly, a large amount of adsorbed oxygen appeared near the B vacancies of Pd/MgO(5)-h-BN catalyst. The experiments outcomes of diffuse reflectance fourier transform spectra analysis of CO (CO-DRIFT) indicated that the carbonate/formate species were easily decomposed to CO 2 on the Pd/MgO(5)-h-BN catalyst than Pd/h-BN catalyst, which might be a reason why the Pd/MgO(5)-h-BN catalyst had high CO oxidation activity. According to above analyses, we provide a new insight for the MgO-h-BN nanomaterials for Pd catalysts for application in CO oxidation reaction.
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Acta Biomaterialia
·
2018
·
IF 6.383
Meili Hou,Yong-E Gao,Xiaoxiao Shi,Shuang Bai,Xiaoqian Ma,Baosheng Li,Bo Xiao,Peng Xue,Yuejun Kang,Zhigang Xu
The goal of nanomedicine is to seek strategies that are more efficient to address various limitations and challenges faced by conventional medicines, including lack of target specificity, poor bioavailability, premature degradability, and undesired side effects. Self-assembling drug amphiphiles represent a prospective nanomedicine for cancer therapy owing to their favorable route of administration and therapeutic efficiency compared with pristine drug counterparts. In this work, we report a class of self-deliverable prodrug amphiphiles consisting of the hydrophilic drug methotrexate (MTX) and the hydrophobic anticancer drugs camptothecin (CPT) and doxorubicin (DOX) for targeted and combinational chemotherapy. The disulfide bond and hydrazone bond, which are subject to stimuli-triggered bond cleavage, were introduced to link these therapeutic agents and form two prodrug amphiphiles, named as MTX-CPT and MTX-DOX, respectively, which could self-assemble into stable prodrug nanoaggregates (NAs) in aqueous media. MTX molecules in the prodrug NAs facilitated NA uptake into tumor cells with high expression of folic acid receptors (FRs). This systemic study provided clear evidence of the synergistic therapeutic effect by co-administrating dual prodrug NAs on various tumor cells in vitro and a xenograft tumor model in vivo . The obtained prodrug amphiphiles provide an efficient strategy for the design of multifunctional drug delivery systems and elaborate therapeutic nanoplatforms for cancer chemotherapy. Statement of Significance This work presents two kinds of prodrug amphiphiles that are carrier free and integrate targeted drug delivery, stimuli-triggered drug release, synergistic therapy, and theranostic function into a single system. Reduction/acid active prodrug amphiphiles can self-assemble into micellar nanoaggregates (NAs) at a very low critical aggregation concentration. These NAs exhibit superior stability in physiological environment and disassemble in the presence of tumor cells expressing folic acid receptors or the high glutathione or in low pH tumoral endosomal environment. The induced disassembly of prodrug NAs can “switch on” the inherent fluorescence of the internalized camptothecin or doxorubicin for the detection of tumor cells. Compared to a single type of prodrug NA, co-administration of dual prodrug combination can produce an evident synergistic therapeutic effect against various tumor cells in vitro and inhibit xenograft tumor growth in vivo . The methotrexate-based prodrug amphiphiles may provide a potential strategy for developing multifunctional nanoplatforms and delivery of multiple therapeutics in chemotherapy.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2018
·
IF 4.229
Jie Guo,Yongjiang Hou,Bo Li,Yulei Liu
Ni–Co–B hollow nanospheres were synthesized by the galvanic replacement reaction using a Co–B amorphous alloy and a NiCl 2 solution as the template and additional reagent, respectively. The Ni–Co–B hollow nanospheres that were synthesized in 60 min (Ni–Co–B-60) showed the best catalytic activity at 303 K, with a hydrogen production rate of 6400 mL hydrogen min −1 g catalyst −1 and activation energy of 33.1 kJ/mol for the NaBH 4 hydrolysis reaction . The high catalytic activity was attributed to the high surface area of the hollow structure and the electronic effect. The transfer of an electron from B to Co resulted in higher electron density at Co sites. It was also found that Ni was dispersed on the Co–B alloy surface as result of the galvanic replacement reaction. This, in turn, facilitated an efficient hydrolysis reaction to enhance the hydrogen production rate. The parameters that influenced the hydrolysis of NaBH 4 over Ni–Co–B hollow nanospheres (e.g., NaOH concentration, reaction temperature, and catalyst loading) were investigated. The reusability test results show that the catalyst is active, even after the fifth run. Thus, the Ni–Co–B hollow nanospheres are a practical material for the generation of hydrogen from chemical hydrides .
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2018
·Vol. 124
·期 6
·1-8
·
IF 1.604
Lin Changwei,Tang Yu,Song Jun,Han Lei,Yu Jingbo,Lu Anxian
In the present study, series of garnet-type Li 6.75+ x La 3− x Sr
x
Zr 1.75 Nb 0.25 O 12 solid electrolytes [LLSZN with various Sr contents ( x = 0.05–0.25)] have been prepared via conventional solid-state method. The effects of Sr contents on their phase structure and ionic conductivity have been systematically investigated on the combined measurements of X-ray diffraction and scanning electron microscopy and alter current impedance spectroscopy. Our results reveal that a phase transition from tetragonal to cubic structure occurs when both Sr and Nb elements is introduced, and such a cubic structure can be stable over the whole Sr contents variation, which is suggested to provide a beneficial impact on the performance of LLSZN. Accordingly, both relative density and total ionic conductivity exhibit a favorable tendency of increasing first and then decreasing with increased Sr contents, wherein a peak value at 93.46% and 5.09 × 10 −4 S cm −1 , respectively, can be well achieved. Particularly, the maximum ionic conductivity is almost twice that of the compared sample (2.93 × 10 −4 S cm −1 ), and possess the minimum activation energy ~ 0.30 eV. Such a modification method, featured with higher efficiency and lower cost, is expected to be helpful for the development of solid electrolyte.
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RSC Advances
·
2019
·Vol. 9
·期 27
·15642-15647
·
IF 3.049
Fuping Tian,Chenxia Qiao,Renyu Zheng,Qiaofeng Ru,Xin Sun,Yifu Zhang,Changgong Meng
A bimetallic–organic porous material (Cu/Co-BTC) with a paddle-wheel structure has been successfully synthesized by a solvothermal approach. The as-synthesized materials were characterized by XRD, SEM, ICP-AES, UV-Vis, TGA and N2 adsorption at 77 K. The prepared Cu/Co-BTC samples were investigated in thiophene (TP) adsorption from model gasolines by the fixed bed adsorption method at 298 K. The results showed that only a small amount of Co could be successfully introduced into the framework of HKUST-1, and the introduction of Co had little effect on the crystalline structure, morphology, porosity, and thermal stability. The bimetallic Cu/Co-BTC with a Cu/Co ratio of 174 displayed significantly improved adsorption desulfurization performance, showing an increase in breakthrough volume by 30% compared with HKUST-1, implying that the central metal in the MOF plays an important role in adsorption desulfurization. The addition of toluene or cyclohexene (3.20–3.30 vol%) as a competitor in the model gasoline led to a decline in desulfurization performance, especially when cyclohexene was added. The bimetallic Cu/Co-BTC showed a slight loss in breakthrough volume by only 5% after regenerating 7 times, displaying an excellent regeneration property.
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Materials Science & Engineering C-Materials for Biological Applications
·
2019
·
IF 4.959
Yimin Sun,Cheng Hu,Yuanyi Yang,Bin Dong,Yi Deng
The surface-inspirable biomaterials have captured extensive attention in simulating microenvironments by mimicking nanoscale architectures and signal molecules in the extracellular matrix (ECM). To activate osteogenic differentiation through biomimetic nanostructures, osteoid-like calcium titanate nanorods (CT) were fabricated via anodization and hydrothermal treatment. SEM, EDS, and XPS were employed to confirm the morphology and chemical composition. The functional fibroin and peptide layers on CT (PFCT) were subsequently applied to provide binding sites and bioactive molecules for osteoblast growth and differentiation. The hydrophilicity obviously increased with the protein layers. PFCT presented enhanced cell viability with pronounced pseudopod extension and continuous proliferation. The osteogenic differentiation analysis revealed that the alkaline phosphatase expression improved in the early stage. The calcium nodes and the collagen secretion were also enhanced. Quantitative polymerase chain reaction assessment indicated that osteogenesis-related markers including ALP , Col1 , and Runx2 , were up-regulated. The in vitro results demonstrated that fibroin/peptide co-functionalized calcium titanate nanorods were efficient to stimulate osteoblasts and improve cell adhesion, proliferation, and differentiation. Therefore, the nanorods can create an osteogenic niche on titanium implants, which can be a promising modification strategy in bone tissue engineering application.
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JOURNAL OF MOLECULAR LIQUIDS
·
2019
·
IF 4.561
Xiangrui Meng,Yijin Mi,Dongling Jia,Ning Guo,Yarui An,Yuqing Miao
Co hydroxide polymorphs (green α-Co(OH) 2 , red β-Co(OH) 2 and brown β-Co(OH) 3 ) formed at separate positions in a test-tube. Diffusion of hydrazine hydrate downward in agar gel facilitated the reaction between hydrazine and Co 2+ leading a dilatational wave of reactant concentration. The resulting periodic Liesegang bands of α-Co(OH) 2 were observed due to the diffusion hindrance of reactants. It can be deduced that the high concentration of Co 2+ causes formation of α-Co(OH) 2 while the low concentrations produce β-Co(OH) 2 . β-Co(OH) 2 is oxidized readily to form brown β-Co(OH) 3 at the upper area of agar gel with high alkali condition and O 2 distribution. This study is helpful to learn the formation of more than one product and prepare multiple materials in single chemical reaction system. In addition, the obtained α-Co(OH) 2 has been stabilized in the gel medium for at least 3 months. It may facilitate its application in many areas especially in electrochemical area since α-Co(OH) 2 typically exhibits higher conductivity and electrocatalysis than β-Co(OH) 2 while in the past its application often is limited by thermodynamically instability.
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ACS Applied Materials & Interfaces
·
2018
·
IF 8.097
Xiangdong Xu,Hongliang Zeng,Dezhi Han,Ke Qiao,Wei Xing,Mark J. Rood,Zifeng Yan
Sodium-ion batteries (SIBs) attract more attention because of sodium’s abundant availability, affordable price, and potential to be an effective anode material. Meanwhile, carbon-based materials provide the most promising anode materials. Because of the large radius of sodium ions, SIBs do not exhibit favorable electrochemical performance. Introducing heteroatoms into the carbon-lattice is an effective strategy to enlarge the interlayer space of carbon-based materials which can improve carbon’s electrochemical performance. In addition, anode materials with a surface-induced capacitive process can enhance the SIB’s electrochemical performance because its capacitive process increases the kinetics of ion diffusion. Here, we describe an SIB’s anode material containing nitrogen and sulfur co-doped graphene sheets [denoted as poly(2,5-dimercapto-1,3,4-thiadiazole) (PDMcT)/reduced graphene oxide (RGO)] which are synthesized via carbonization of PDMcT polymerized on the surface of GO. PDMcT/RGO exhibited high capacities (240 mA h g–1 at 500 mA g–1), improved rate performance (144 mA h g–1 at 10 A g–1), and good cycling stability (153 mA h g–1 after 5000 cycles at 5000 mA g–1). These unique results are attributed to the enlarged interlayer spacing and electronic conductivity from the heteroatoms which facilitate the sodium ion’s insertion and electron transport. These results represent that PDMcT/RGO is a great potential anode material for SIBs.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2019
·Vol. 30
·期 16
·15097-15104
·
IF 2.195
Mi Yijin,Zhao Hui,Jia Dongling,Miao Yuqing
Bosk-like Co–Sn–Se monocrystals are deposited on porous Ti plate through a hydrothermal method. The prepared Co–Sn–Se was characterized with morphology, composition and electrocatalytic properties. Electrochemical measurements revealed that the Ti/Co–Sn–Se electrodes exhibited great catalytic performance for hydrogen evolution reaction with the low onset overpotential of − 50 mV, the small Tafel slope of 83 mV/dec and good stability over an extended period of 34,000 s. The high electrocatalytic activity of bosk-like Co–Sn–Se monocrystals, the fast electron transfer between electrodes and catalysts, and the high conductivity of Ti contribute to their acceptable electrocatalytic performance.
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