RSC Advances
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2020
·Vol. 11
·期 2
·711-720
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IF 3.119
Shizhu Song,Tao Yang,Rongwei Shi,Qi Li
High-density nitrogen-doped porous carbon catalysts have been regarded as promising alternatives to precious metals in proton-exchange membrane fuel cells (PEMFC) and metal–air batteries based on the oxygen reduction reaction (ORR). We herein synthesized high-density pyridinic and graphitic N-doped hollow carbon nanospheres (G&P N-HCS) using a high-yield amino-1H-tetrazole (ATTZ) via a self-sacrificial-template method. The synthesized G&P N-HCS shows a high N content (15.2 at%), in which pyridinic (Pr) and graphitic (Gr) N are highly reactive for the ORR catalysis. We found that the half-wave potential and limiting current density of G&P N-HCS are comparable to the state-of-the-art Pt/C, whereas its cyclic durability is much superior to that of Pt/C. Experimental results indicate that an optimal ratio (1 : 1) between Gr N and Pr N in G&P N-HCS exhibits the highest ORR performances, rather than Gr N-dominated N-HCS or Pr N-dominated N-HCS. Notably, N-HCS containing only Gr N and Pr N has poor catalytic performance for ORR in alkaline electrolytes. Density functional theory (DFT) simulations untangle the catalytic nature of Pr and Gr N and decipher the relations between the N type(s) and total N content required for the ORR catalysis. This study provides a new way to design efficient N-doped porous carbon-enriched active sites, and solves the cathode catalyst in the commercialization of PEMFC and metal–air batteries.
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INORGANIC CHEMISTRY
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2020
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IF 4.825
Bo Ni,Hongzhi Cao,Chengkai Zhang,Shengli Li,Qiong Zhang,Xiaohe Tian,Dandan Li,Jieying Wu,Yupeng Tian
The construction of novel classes of photosensitizers for efficient reactive oxygen species (ROS) generation is of great interest, yet it is a challenge. In this work, a bis(terpyridine)zinc(II) complex (namely, ZnL1) with two-photon absorption activity as an efficient ROS photogenerator was synthesized. Benefiting from the coordinated Zn, the decreased singlet–triplet energy gap favors the intersystem crossing process facilitating the singlet oxygen (1O2) generation via energy transfer. In addition, it makes the superoxide radical (O2·–) generation easier. This is an extremely rare study on two-photon excited ROS generation by activating type I and type II processes based on a cheaper and bioaccessible Zn complex.
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CHEMICAL ENGINEERING JOURNAL
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2020
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IF 10.652
Yanqiao Xu,Ting Chen,Zhixiang Xie,Weihui Jiang,Lianjun Wang,Wan Jiang,Xiaojun Zhang
Understanding the surface characteristic-optical property relationship of Cu-In-Zn-S (CIZS) quantum dots (QDs) is necessary for tuning the optoelectronic performances, and the photoluminescence quantum yields (PLQYs) of CIZS QDs prepared in aqueous solution are still relative low compared with that of obtained in organic phase, which seriously restricts their applications. Herein, an efficient method was proposed to prepare CIZS/ZnS/PVP composites and their application in white light-emitting diodes (WLEDs) was investigated. CIZS QDs were synthesized through hydrothermal process with the assistance of ionic liquid (IL), which could enhance the PL performance and reduce the reaction time simultaneously. The effects of hydrothermal temperature and time on the phase composition, morphology, and optical properties of CIZS QDs were systematically investigated. The results showed that the BF 4 − anion played a crucial role in boosting the emission property of CIZS QDs owing to the effective reduction of dangling bonds on the surface of QDs, which induced by the corrosion of F − deriving from the decomposition of BF 4 − . The surface modulation led to the improvement of PLQY from 6.2% to 8.4%. In addition, the PLQY of QDs was further improved to 31.2% by coating with ZnS shell around CIZS cores. Furthermore, highly luminescent CIZS/ZnS/PVP composites were prepared to eliminate the aggregation-induced fluorescence quenching effect, which was beneficial to the application in WLEDs. Consequently, a WLED achieved the color rending index (CRI) of 87.2, correlated color temperature (CCT) of 4977 K, and luminous efficacy (LE) of 90.11 lm/W by using the orange-yellow CIZS/ZnS/PVP composites and green Lu 3 Al 5 O 12 :Ce 3+ phosphors as the color conversion layer, suggesting the potential for solid state lighting application.
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Nanomaterials
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2020
·Vol. 10
·期 2
·330
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IF 4.324
Qilei Wu,Huihui Jin,Bin Zhang,Siqi Huo,Shuang Yang,Xiaogang Su,Jun Wang
A facile method for the preparation of microwave absorbers with low density, high microwave absorptivity, and broad band is of paramount importance to the progress in practical application. Herein, commonly-used metal organic frameworks (MOFs) prepared just by mechanical stirring in methanol at room temperature were chosen as sacrificial templates to synthesize porous carbon composites with tunable dielectric and magnetic properties. With the replacement of Co atoms on the surface of zeolitic imidazolate framework-67 (ZIF-67) by Zn atoms, a Co-doped porous carbon composite with a low-dielectric amorphous carbon/Zn shell was constructed after annealing, leading to excellent impedance matching condition. Consequently, the as-obtained composite (Co/C@C-800) shows marvelous microwave absorption properties with an absorption capacity of −43.97 dB and a corresponding effective absorption bandwidth of 4.1 GHz, far exceeding that of the traditional porous carbon and composites directly derived from ZIF-67. The results provide a convenient way to modify MOFs for enhanced microwave absorption materials from the synergy of dielectric and magnetic losses.Keywords:MOFs-derived carbon composites;porous structure;impedance match;microwave absorption
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APPLIED ORGANOMETALLIC CHEMISTRY
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2020
·Vol. 34
·期 11
·e5950
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IF 3.14
Fei-Fei Wang,Zan Liu,Zhi-Lin Cheng
The interface issue of two-dimensional (2D) nanomaterials has seriously restricted their applications in the past. To date, there have been few reports on the friction behavior of 2D MOFs. Herein, 2D Zn(Bim)(OAc) metal–organic framework structure nanosheets with a thickness of ca. 4 nm were successfully prepared via convenient ultrasonic-assisted exfoliation in solvents. For the first time, we probed the dispersion performance of the as-obtained 2D Zn(Bim)(OAc) in different oils, and intensively investigated the tribological behavior. The results indicated that the as-obtained 2D Zn(Bim)(OAc) used as an additive showed the preferable friction reducing performance and wear resistance in liquid paraffin, and showed the better dispersivity in glycerol.
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Journal of Materials Chemistry A
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2020
·Vol. 8
·期 19
·9832-9842
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IF 11.301
Xinyi Luo,Zhaoxu Li,Meifang Luo,Chaozhong Guo,Lingtao Sun,Shijian Lan,Ruyue Luo,Lan Huang,Yuan Qin,Zhongli Luo
The low surface density of catalytic sites and undeveloped porosity have become a bottleneck for boosting the oxygen reduction reaction (ORR) activity of carbon catalysts. Herein, we propose a novel strategy for the synthesis of porous semi-tubular iron–nitrogen-doped-carbon nanostructures via a two-step calcination of a ferriporphyrin-based biomaterial by means of a natural tubulose nanoclay as a morphology-controlled template, followed by post Zn-activation and acid-leaching processes. The formation of mesopore-dominated semi-tubular carbons is beneficial for accelerating the ORR catalysis rate and improving the catalytic activity owing to the increased mass transport capacity of reactants to nitrogen-rich catalytic sites existing in the pores. The resultant doped-carbon catalyst not only displays excellent electrocatalytic behavior with an ORR onset potential of ∼1.01 V and a half-wave potential of ∼0.85 V, but also exhibits a maximum power density of ∼191 mW cm−2, comparable to that of a Pt catalyst in a primary Zn–air battery, suggesting a very promising candidate for prevalent energy-conversion devices. It is probably due to the production of mesopore-dominated semi-tubular structures, more active-nitrogen species and dense surface active sites. This work can pave a new way for the original design of low-cost and high-performance doped-carbon catalysts by using natural biomaterials for widespread application in electrochemical energy devices.
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CLAYS AND CLAY MINERALS
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2019
·Vol. 67
·期 4
·325-333
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IF 1.835
Guo Yu-Hua,Pan Guo-Xiang,Xu Min-Hong,Wu Tao,Wang Yong-Ya
Adsorption desulfurization is a potential new method for deep desulfurization of fuel oil. The development of adsorbents with high adsorption capacity and selectivity is the core of deep adsorption desulfurization. The adsorption behavior of thiophene in MCM-41 mesoporous materials modified by various metal ions was studied in order to understand the adsorption desulfurization process of molecular sieves. The Fe-, Co-, and Zn-modified MCM-41 materials were prepared using a one-step in situ hydrothermal synthesis method. The modified MCM-41 molecular sieves maintained the mesoporous structure, and the metal ions had specific dispersion on the surface of the molecular sieves. Adsorption of thiophene on the surfaces of molecular sieves had both physical and chemical characteristics. The adsorption desulfurization performance of the modified molecular sieve was superior to that of the pure silica molecular sieve. In the simulated gasoline with sulfur content of 220 μg/g, when the amount of adsorbent used was 100 mg, the adsorptive desulfurization performance tended to be in equilibrium, and the optimum adsorption temperature was 30°C. Fe-MCM-41 and MCM-41 molecular sieves reached adsorption equilibrium after ~60 min, but the desulfurization rate of Co-MCM-41 and Zn-MCM-41 still increased slightly. The kinetic simulation results indicated that the pseudo-second-order kinetics adsorption model described well the adsorption process of thiophene on molecular sieves. The molecular sieve Fe-MCM-41 had the best desulfurization performance with an equilibrium adsorption capacity of 14.02 mg/g and the desulfurization rate was ~90%.
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Chemistry-An Asian Journal
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2019
·Vol. 14
·期 23
·4375-4382
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IF 3.698
Bo Tang,Shuang Li,Wei-Chao Song,Yan Li,En-Cui Yang,Xiao-Jun Zhao,Landong Li
Graphical Sleepy Hollow : A hollow-structured Zn−Co based zeolitic imidazole framework, obtained from post-synthesis chemical etching, serves as a robust heterogeneous catalyst for the cycloaddition of CO 2 with epoxides to yield the corresponding cyclic carbonates. The efficient chemical conversion of carbon dioxide (CO 2 ) into value-added fine chemicals is an intriguing but challenging route in sustainable chemistry. Herein, a hollow-structured bimetallic zeolitic imidazole framework composed of Zn and Co as metal centers (H-ZnCo-ZIF) has been successfully prepared via a post-synthetic strategy based on controllable chemical-etching of the preformed solid ZnCo-ZIF in tannic acid. The creation of hollow cavities inside each monocrystalline ZIFs could be achieved without destroying the intrinsic frameworks, as characterized by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction technologies. The as-synthesized H-ZnCo-ZIF exhibited remarkable catalytic activity in the cycloaddition of CO 2 with epoxides to the corresponding cyclic carbonates, outperforming the solid ZnCo-ZIF analogue due to the improved mass transfer originating from the hollow structure. More importantly, due to stabilization of metal centers in the ZIF framework by the tannic acid shell, H-ZnCo-ZIF exhibited good recyclability, and no activity loss could be observed in six runs. The present study provides a simple and effective strategy to enhance the catalytic performance of ZIFs by creating a hollow structure via chemical etching.
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MICROCHEMICAL JOURNAL
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2019
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IF 3.206
Yueran Zhu,Yunguang Lu,Longyan Shi,Yaling Yang
A green, reliable and simple assay for Fluoroquinolone derivatives (FQs) is developed based on Mono-(6-Amino-6-Deoxy)-β-Cyclodextrin (β-CD) were modified on the surface of N,Zn co-doped carbon dots (N,Zn-CDs). FQs not only enhance β-CD-N,Zn-CDs fluorescence intensity, but also red-shift. Since FQs has the same effect on the fluorescence of β-CD-N,Zn-CDs, so ofloxacin (OFL) as a representative for analysis. Under optimized detection conditions, the linear range is 0.075–3.75 μM and the LOD is 0.05 μM (S/N = =3). Finally, the proposed method was successfully applied in the determination of OFL in milk and domestic water with satisfactory recoveries.
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ELECTROCHIMICA ACTA
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2019
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IF 5.383
Haoqing Ji,Mengfan Wang,Sisi Liu,He Sun,Jie Liu,Tao Qian,Chenglin Yan
Pyridinic and graphitic nitrogen are recognized as the most promising dopants for promoting oxygen reactions since they are beneficial to the formation of corresponding C–N bonds as efficient active sites. However, complete control of such efficient nitrogen-doping sites in carbon materials is difficult to realize in practice in a pyrolysis process . Here, we present maximized pyridinic and graphitic nitrogen-doped oxygen electrode via the precise use of nitrogen-containing precursors and carbonization temperature. The critical roles of pyridinic and graphitic nitrogen dopants in enhancing oxygen reaction activity are unraveled and this highly active material exhibits a remarkable half-wave potential of 0.89 V versus the reversible hydrogen electrode (vs. RHE) for oxygen reduction reaction (ORR) and a small potential gap of 0.78 V between ORR and oxygen evolution reaction (OER) in 0.1 M KOH, which is one of the best to date among metal-free bifunctional electrocatalysts . Both zinc-air batteries using liquid electrolytes and the all-solid-state batteries assembled with such air cathodes exhibit excellent cycle performance and reversibility, which can be expressly observed by in-situ X-ray diffraction (XRD) characterization. This nitrogen dopants engineering strategy gives an effective methodology to make full use of nanocarbon materials for their practical applications in next-generation powerful and durable energy devices.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2022
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IF 6.371
Jingyun Wang,Wei Li,Xiaofang Chen,Aisheng Huang
Transition metal phosphides are considered as promising alternatives to noble-metal based electrocatalysts for water splitting due to their bifunctional catalytic activity. The modulation of morphology and electronic structure is an efficient strategy to improve the mass transport and electronic conductivity of metal phosphides, but still faces a great challenge to achieve this conjoint regulation. Herein, a facile Zn-doped strategy was developed to synthesize cobalt phosphide (CoP) catalyst with thickness-controlled porous nanosheet structure. At the current density of 10 mA cm −2 , the optimized Zn 0.1 -CoP catalyst delivers an overpotentials of 290 mV and 98 mV for OER and HER , respectively. The cell voltage for the overall water splitting is 1.57 V to reach the current density of 10 mA cm −2 , outperforming the counterparts of noble metal-based Pt/C and IrO 2 catalysts. The density functional theory (DFT) calculations reveal that Zn doping can effectively improve the conductivity and regulate the electronic structure of CoP, thus resulting in fast charge transfer transport and reduced energy barrier of the rate-determining step. This work provides a favorable strategy for the rational design of bifunctional catalysts with high-performance for overall water splitting.
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Acta Biomaterialia
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2022
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IF 10.633
Xian Tong,Yue Han,Runqi Zhou,Wanying Jiang,Li Zhu,Yuncang Li,Shengbin Huang,Jianfeng Ma,Cuie Wen,Jixing Lin
The unique combination of biodegradability , biocompatibility, and functionality of zinc (Zn)-based alloys makes them highly desirable for a wide range of medical applications. However, a long-standing problem associated with this family of biodegradable alloys in the as-cast state is their limited mechanical strength and slow degradation rate. Here we report the development of Zn-xDy (x = 1, 3, and 5 wt.%) alloys with high strength, ductility, cytocompatibility, antibacterial ability, and appropriate degradation rate for biodegradable bone-implant applications. Our results indicate that the mechanical properties of Zn–xDy alloys were effectively improved with increasing Dy addition and hot-rolling due to the second-phase strengthening. The hot-rolled (HR) Zn–3Dy alloy showed the best combined mechanical performance with an ultimate tensile strength of 270.5 MPa, a yield strength of 214.8 MPa, an elongation of 55.1%, and Brinell hardness of 75.9 HB. The corrosion and degradation rates of HR Zn–xDy alloys in Hanks’ solution gradually increased with increasing Dy addition due to the intensification of galvanic corrosion . The HR Zn–3Dy alloy showed high antibacterial ability against S. aureus and cytocompatibility toward MC3T3-E1 cells among all the HR alloys. Overall, the HR Zn–3Dy alloy can be considered a promising biodegradable material for bone implants. Statement of significance This work reports on Zn–xDy (x = 1, 3, and 5%) alloys fabricated by Dy alloying followed by hot-rolling for biodegradable bone-implant applications. Our findings demonstrate that the hot-rolled (HR) Zn–3Dy alloy showed the best combined mechanical performance with an ultimate tensile strength of 270.5 MPa, a yield strength of 214.8 MPa, an elongation of 55.1%, and Brinell hardness of 75.9 HB. The corrosion and degradation rates of HR Zn–xDy alloys in Hanks’ solution gradually increased with increasing Dy addition due to the intensification of galvanic corrosion. Furthermore, the HR Zn–3Dy alloy showed greater antibacterial ability against S. aureus and the best cytocompatibility toward MC3T3-E1 cells among all the HR alloys.
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