ANALYST
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2018
·Vol. 143
·期 21
·5185-5190
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IF 3.864
Yunlei Zhou,Huanshun Yin,Yue Wang,Chengji Sui,Minghui Wang,Shiyun Ai
A simple and sensitive electrochemical aptasensor was constructed for zeatin detection, where MoS2 nanosheets were used as the immobilization matrix for gold nanoparticles (AuNPs), and AuNPs were employed as the immobilization matrix to probe DNA. After the aptamer DNA and assist DNA hybridized with probe DNA, Y-type DNA can be formed with two biotins at the terminals of aptamer DNA. Then, avidin modified alkaline phosphatase (Avidin-ALP) can be further modified on the electrode surface through the biotin and avidin interaction. Under the catalytic effect of ALP, p-nitrophenylphosphate disodium (PNPP) can be hydrolyzed to produce p-nitrophenol (PNP). However, in the presence of zeatin, the formed Y-type DNA can be destroyed due to the formation of the zeatin–aptamer conjugate, which further reduces the amount of PNP and leads to the decrease of the oxidation signal of PNP. Under the optimum conditions, the change of the oxidation peak current of PNP was inversely proportional to the logarithm value of zeatin concentration in the range of 50 pM–50 nM. The detection limit was calculated to be 16.6 pM. This electrochemical method also showed good detection selectivity and stability. The potential applicability of this method was proved by detecting zeatin in real samples.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
·
IF 11.698
Xue Bai,Yanyan Du,Xiaoyun Hu,Yudong He,Chunliang He,Enzhou Liu,Jun Fan
A novel RP-MoS 2 /rGO nanocomposite as low-cost, environmental sustanable, stability and high-performance photocatalyst was successfully fabricated for the first time through a facile two-step hydrothermal method. Even without a noble-metal cocatalyst, the introduction of MoS 2 /rGO hybrid made RP exhibit excellent photocatalytic performance, including photoreduction of Cr (VI) and photooxidation of different organic pollutants, owing to the increased number of excited electrons/holes and enhanced separation efficiency of charge carriers. Importantly, the synergy of photocatalytic reduction and oxidation, as well as photocatalysis and adsorption played an important role in enhancing photocatalytic activity and reaching a high efficiency. Besides, the chemical structure of the RP-MoS 2 /rGO with P–S and P O bands ensure the stability of the nanocomposite materials. Overall, the photocatalytic elimination of the Cr (VI)-Organic molecule coexistence system in this work shows promising application to treatment the reality wastewater.
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ACS Applied Energy Materials
·
2018
·
IF 0
Xiaorong Gan,Lawrence Yoon Suk Lee,Kwok-yin Wong,Tsz Wing Lo,Kwun Hei Ho,Dang Yuan Lei,Huimin Zhao
The phase transition of multilayer MoS2 nanosheets from semiconducting 2H to metallic 1T (2H/1T) has been realized mainly by chemical methods (e.g., Li intercalation). Here, we develop a simple yet effective method, cyclic voltammetry, to successfully tune the 2H/1T phase transition of multilayer MoS2 nanosheets without using intercalation species. The phase transition is triggered by the electrochemical incorporation of S vacancies (obtained by electrochemical etching), which on the one hand injects electrons into the framework of S–Mo–S and on the other hand facilitates the sliding of S planes. Density functional theory calculations show that O doping in the framework of S–Mo–S decreases the energy barrier for forming S vacancies and stabilizes the 1T-phase by occupying the 4d orbital of Mo. Our calculations further show that the presence of S vacancies and O incorporation not only reduces the bandgap of MoS2, indicating an increased conductivity, but also decreases the hydrogen adsorption free energy, implying significant improvement of hydrogen evolution reaction (HER) activity. Indeed, the overpotential and Tafel plot of the electrochemically treated MoS2 nanosheets are decreased respectively by 174 mV and 25 mV/dec at a cathodic current density of 10 mA cm–2 compared with pristine 2H-MoS2 nanosheets. The HER experiment also reveals the order of catalytical activity for the studied phases and structural defects: 1T-MoS2 > S vacancies > O doping >2H-MoS2. Our study has provided a new route to control the phase transition of multilayer MoS2 nanosheets with promising applications potentially in catalysis and optoelectronics.
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JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY
·
2018
·Vol. 319
·期 1
·379-386
·
IF 1.181
Shao Dadong,Liu Xinghao,Hayat Tasawar,Li Jiaxing,Ren Xuemei
A novel adsorbent for enrichment of trace uranium (U(VI)) ions in aqueous solution is designed based on the excellent adsorption capacity of poly(amidoxime) (PAO) and the excellent chemical properties of MoS 2 . Specifically, PAO/MoS 2 is prepared by plasma induced polymerization of acrylonitrile on MoS 2 surfaces, followed by amidoximation treatment with NH 2 OH. This as-prepared PAO/MoS 2 was applied as adsorbent for the separation of U(VI) from aqueous solutions. The modified PAO enhance greatly the adsorption capability of MoS 2 for U(VI) in aqueous solutions. PAO/MoS 2 presents excellent selectivity for U(VI) in aqueous solution, suggesting PAO/MoS 2 can separate U(VI) with high selectivity.
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ANALYST
·
2018
·Vol. 143
·期 15
·3702-3707
·
IF 3.864
Jun-Tao Cao,Fu-Rao Liu,Fang Hou,Juan Peng,Shu-Wei Ren,Yan-Ming Liu
The cathodic electrochemiluminescence (ECL) behaviour of nontoxic MoS2 quantum dots (QDs) was studied for the first time using potassium peroxydisulfate as the co-reactant. Ag-PAMAM NCs, serving as difunctional tags for quenching and enhancing ECL of MoS2-reduced graphene oxide composites, were introduced into the ECL detection system for signal amplification. By modulating the interparticle distance between MoS2 QDs and Ag-PAMAM NCs, the ECL quenching from resonance energy transfer and the ECL enhancement from surface plasma resonance were realized. Coupling the good ECL performance of MoS2 QDs with the excellent ECL quenching and enhancement effects of Ag-PAMAM NCs, a novel MoS2 QDs-based ECL biosensing platform for sensitive detection of microRNA-21 was achieved with a detection limit of 0.20 fmol L−1 (S/N = 3). This method was successfully applied to the determination of microRNA-21 in human serum samples with recoveries of 90.0–110.0%, suggesting great potential for its applications in biological and chemical analysis.
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MICROCHIMICA ACTA
·
2018
·Vol. 185
·期 12
·1-8
·
IF 5.705
Zhang Feng,Liu Hua,Liu Qing,Su Xingguang
A ratiometric fluorescence method is described for the determination of the anticancer drug 6-mercaptopurine (6-MP). The method is based on the use of fluorescent MoS 2 quantum dots (MQDs) and of the enzyme horseradish peroxidase (HRP). In the absence of 6-MP, HRP catalyzes the oxidation of o-phenylenediamine (OPD) by H 2 O 2 to form 2,3-diaminophenazine (DAP). This leads to quenching of the violet fluorescence of MQDs (measured at excitation/emission wavelengths of 360/415 nm), while the strong yellow fluorescence of DAP (peaking at 560 nm) becomes increasingly strong. In the presence of 6-MP, however, it will be preferentially oxidized by the HRP/H 2 O 2 system to form a disulfide dimer. Hence, less H 2 O 2 is available for the oxidation of OPD and less DAP will be formed. This results in the recovery of the violet fluorescence and a decrease of the yellow fluorescence. The ratio of the two signals can be used to quantify either H 2 O 2 or 6-MP. Linear responses are observed for H 2 O 2 in 0.5–140 μM concentration range, and for 6-MP in the 0.5–70 μM concentration range, with detection limits of 0.1 μM and 0.29 μM, respectively. The method was applied to the determination of 6-MP in spiked human urine and gave satisfactory results.
Schematic of an enzymatic fluorometric method for determination of 6-mercaptopurine (6-MP). It is based on the presence of 6-MP that can inhibit the HRP-catalyzed oxidation of o-phenylenediamine (OPD) to form 2,3-diaminophenazine (DAP). Hence, the fluorescence resonance energy transfer (FRET) between DAP and MoS 2 quantum dots (MQDs) is suppressed.
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Environmental Science-Nano
·
2018
·Vol. 5
·期 12
·2876-2887
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IF 6.087
Wei Ma,Binghua Yao,Wen Zhang,Yangqing He,Yan Yu,Jinfen Niu,Cheng Wang
Multi-flaw MoS2 nanosheets were synthesized by a hydrothermal method by controlling the molar ratio of Mo and S. The physical and chemical properties and structures of the samples were characterized by SEM, TEM, N2 adsorption/desorption isotherms, XRD, Raman spectroscopy, and XPS. The construction of flaws with abundant exposed edges in the ultrathin MoS2 nanosheets played an important role in improving the piezocatalytic performance for the degradation of antibiotic ciprofloxacin (CIP) by forming the active sites. Compared with flaw-free MoS2, multi-flaw MoS2 nanosheets had a high number of atomic layers (abundant odd numbers of atomic layers) and exhibited excellent adsorption-piezocatalytic ability, decomposing 99% of CIP in 30 s under ultrasonic irradiation. Furthermore, the total organic carbon (TOC) analysis indicated that 56% of CIP was completely mineralized after 5 min of ultrasonic irradiation. The eradication mechanism of CIP followed pseudo-second-order kinetics with a maximum degradation rate constant of 1.29 L mg−1 s−1. The superior piezocatalytic performance of multi-flaw MoS2 nanosheets was mainly attributed to the highly efficient separation of electron–hole pairs caused by the strain-induced piezoelectric field (an internal electric field). Active species trapping and terephthalic acid (TA) fluorescence experiments demonstrated that the hydroxyl radicals (˙OH) were the major reactive oxygen species that degraded CIP. In addition, UPLC-MS analysis was used for monitoring the intermediates in CIP decomposition. The complete opening of the piperazine and quinolinic rings and the formation of simpler aliphatic compounds were observed. A possible degradation pathway was proposed based on the UPLC-MS data. The ultrafast degradation efficiency of multi-flaw MoS2 nanosheets could be used for practical environmental remediation applications.
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Inorganic Chemistry Frontiers
·
2018
·Vol. 5
·期 11
·2948-2954
·
IF 5.106
Yuanxin Du,Ji Xiang,Kun Ni,Yapei Yun,Guodong Sun,Xiaoyou Yuan,Hongting Sheng,Yanwu Zhu,Manzhou Zhu
Atomically precise nanoclusters (NCs) have been widely used as catalysts in many reactions to investigate the structure–activity relationship due to their ultrasmall sizes, well-defined structures and precise compositions, especially bimetallic NCs can further promote the catalytic activity by the synergistic effects of heteroatoms. For electrocatalytic hydrogen evolution reaction (HER) catalysts, a common method to improve the performance is coupling with a nano-metal, but the origin of the enhancement is still unclear due to the diversity and complexity of the nanometal supported composites. Here, we take MoS2 (a star HER electrocatalyst) as an example, to report a strategy to boost the activity and give insight into the activity enhancement of it by combining with bimetallic atomically precise NCs. The crystal structure of this new NC is determined by X-ray crystallography, and its precise composition is identified as Au2Pd6S4(PPh3)4(C6H4F2S)6 (Au2Pd6 for short). The Au2Pd6/MoS2 show significantly improved HER activity and robust durability compared to the single component Pd3 or Au2/MoS2 and bare MoS2. This is attributed to the appropriate adsorption behavior of H atoms on Au2Pd6/MoS2 and the electronic interactions between NCs and MoS2, according to the combination of experiment and theory. This study presents a new strategy to improve the electrocatalytic activity of 2D materials such as MoS2 and sheds light on the origin of the promotion effects at the atomic level.
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JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 54
·期 20
·13247-13254
·
IF 3.442
Liu Hao,Chen Bochao,Liao Libing,Fan Peng,Hai Yun,Wu Yuanyuan,Lv Guocheng,Mei Lefu,Hao Huiying,Xing Jie,Dong Jingjing
Metallic 1T MoS 2 greatly benefits the supercapacitance of MoS 2 due to its considerably higher conductivity as compared to semiconducting 2H MoS 2 . Alkali metals, such as Li, Na and K, are always used to prepare 1T MoS 2 through intercalation of alkali metal ions into the interlayer of 2H MoS 2 . Nevertheless, the influences of the alkali-earth metals as the guest in the interlayer of MoS 2 on its structure and electrochemical capacitor performance are rarely investigated. Herein, we introduced hydrated Mg ions as the guest into MoS 2 nanosheets. The interlayer spacing was increased to 1.144 nm after the introduction of hydrated Mg ions, larger than that of the pristine MoS 2 (0.620 nm) and restacking MoS 2 (0.626 nm). The enlarged interlayer spacing can accommodate more ions during intercalation process. Moreover, the 1T phase concentration after the introduction of hydrated Mg ions was as high as ~ 90%, which benefits the charge transfer during the charging/discharging processes. Consequently, the specific capacitance of the MoS 2 with Mg guest ions as well as the energy densities and power densities was greatly improved as compared to those of the restacking MoS 2 or pristine MoS 2 counterparts. The present work not only demonstrated a new strategy for engineering the physical properties and improving the electrochemical performance of MoS 2 supercapacitor electrode through pre-intercalation of alkali-earth metal ions in the interlayer of MoS 2 , but also has directive significance for the design of other layered electrode materials for energy storage systems.
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DALTON TRANSACTIONS
·
2019
·Vol. 48
·期 32
·12186-12192
·
IF 4.052
Jiang-Yan Xue,Fei-Long Li,Zhong-Yin Zhao,Cong Li,Chun-Yan Ni,Hong-Wei Gu,Pierre Braunstein,Xiao-Qing Huang,Jian-Ping Lang
The development of bifunctional non-noble metal electrocatalysts demonstrating high activity and stability for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great significance for renewable and clean energy. In this work, we report hierarchically structured integrated Fe–MoS2/Ni3S2/NF (NF = nickel foam) materials prepared by a facile in situ solvothermal method, and among them, the Fe-doped MoS2 was assembled into spine-like nanorods. The optimized electrocatalyst (denoted as Fe–MoS2/Ni3S2/NF-2) demonstrated excellent activity and durability for performing the HER and OER in an alkaline electrolyte (pH = 14) with low overpotentials of 130.6 mV and 256 mV (vs. RHE) at a current density of 10 mA cm−2, as well as no significant loss in catalytic performance even after 2000 cyclic voltammetry (CV) cycles. An outstanding durability of 180 h could be achieved for OER. The overall water splitting made up of the two-electrode system with Fe–MoS2/Ni3S2/NF-2 as both the anode and the cathode required a voltage of only 1.61 V to drive a current density of 10 mA cm−2 along with an outstanding long-term stability of 20 h, displaying its great potential for application in water splitting. The effective construction of multi-component synergistic structures shows a good pathway for high-performance electrocatalysis and energy storage.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Chengbo Wei,Chuan Liu,Linna Gao,Yanfang Sun,Qingyun Liu,Xiao Zhang,Jinxue Guo
Integrating heterogeneous hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts into compatible composite catalysts with specific interfaces and structures holds great promise for the development of efficient bifunctional catalysts for overall water splitting. Herein, heterogeneous MoS 2 -Ni(OH) 2 catalyst supported by Ni foam (MoS 2 @Ni(OH) 2 /NF) is developed, in which the Ni(OH) 2 nanorod array is grafted with MoS 2 nanosheets . The hierarchical 1D/2D structures benefit not only the exposure of catalytic site but also the facilitated charge transfer. The heterointerfaces allow the synergism of electric structure modulation for improved catalytic activity and kinetics towards HER, OER, and overall water splitting. MoS 2 @Ni(OH) 2 /NF achieves a current density of 10 mA cm −2 at low overpotentials of 134 and 233 mV for HER and OER in 1 M KOH, respectively. Moreover, a cell voltage as low as 1.46 V is obtained to afford 10 mA cm −2 in a tow-electrode electrolyzer using MoS 2 @Ni(OH) 2 /NF as bifunctional catalysts, assuring it superior to most of the reported noble-metal-free bifunctional electrocatalysts. Such heterogeneous design of composite catalyst should shed light on the exploration of functional materials for energy applications.
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ACS Applied Materials & Interfaces
·
2018
·
IF 8.097
Mao-Cheng Liu,Yan Xu,Yu-Xia Hu,Qing-Qing Yang,Ling-Bin Kong,Wen-Wu Liu,Wen-Jun Niu,Yu-Lun Chueh
We demonstrate, for the first time, a new method of fabricating hybrid MoS2/poly(ethyleneimine)-modified graphene oxide (PEI-GO) composites assembled through electrostatically charged interaction between the negatively charged MoS2 nanosheets and positively charged PEI-GO in an aqueous solution. The GO can not only improve the electronic conductivity of the MoS2/PEI-GO composites, leading to an excellent charge-transfer network, but also hamper the restacking of MoS2 nanosheets. The composition ratios between MoS2 and PEI-GO were also optimized with the highest specific capacitance of 153.9 F g–1 where 96.0% of the initial specific capacitance remains after 6800 cycles. The specific capacitance of only 117.5 F g–1 was observed for the pure MoS2 nanosheets, and 68.2% of the initial specific capacitance was achieved after 5000 cycles. The excellent electrochemical performance of the hybrid MoS2/PEI-GO composites was demonstrated by establishing an asymmetric supercapacitor with a MoS2/PEI-GO-based negative electrode and an activated-carbon positive electrode. The asymmetric supercapacitor provided a maximum capacitance of 42.9 F g–1, and 93.1% of the initial capacitance was maintained after 8000 cycles. Furthermore, a MoS2/PEI-GO//activated-carbon asymmetric supercapacitor delivered an energy density of 19.3 W h kg–1 and a power density of 4500 W kg–1, indicating the potential of the hybrid MoS2/PEI-GO composites in electrochemical energy storage applications.
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