A chemiresistive sensing scheme to sensitively and discriminatively detect O3 and NO2 at room temperature is achieved by tailoring the sensing performances of MoS2 UNs with Zn2+ doping. The ...discriminative ability of the sensor array based on MoS2 UNs makes the discriminative, continuous and low-cost detection of O3 and NO2 possible within 14s.
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•The p-type MoS2 ultrathin nanosheets by doping Zn2+ were prepared and the sensing performances of MoS2 were successfully tailored.•A chemiresistive sensor array with a tailoring response by using Zn2+ doping tailored MoS2 was developed.•The sensor of MoS2 with 5% Zn2+ exhibited the detection limits of 17 and 215ppb for O3 and NO2, respectively.•The sensor array can identify O3, NO2 and other analytes within 14s in the real-world detection.
One of the most important issues in the development of gas sensors for monitoring gaseous pollutants, such as ozone (O3) and nitrogen dioxide (NO2), is the fabrication of sensor arrays that possess different responses for recognizing patterns of different analytes. Here, we develop a chemiresistive sensor array with a tailoring response by using Zn2+ doping tailored molybdenum disulfide (MoS2). Compared with the sensor of pure MoS2, the responses of the sensor of MoS2 with 5% Zn2+ toward five analytes, including O3 and NO2, are improved by more than 160%, indicating that Zn2+ doping successfully tailor the sensing performances of MoS2 matrix. Thus, this will be a promising approach to constructing a versatile sensor array, by doping a wide variety of metallic ions and tailoring the doping amounts in the MoS2 matrix. Furthermore, the sensor of MoS2 with 5% Zn2+ exhibits the detection limits of 17 and 215ppb for O3 and NO2, respectively. The sensor array can identify O3, NO2 and other analytes within 14s in the real-world detection. This approach to fabricating a tunable and discriminative sensor array may lead to a valuable real-world application for the continuous and low-cost monitoring of gaseous pollutants.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Triacetone triperoxide (TATP) is a self-made explosive synthesized from the commonly used chemical acetone (C₃H₆O) and hydrogen peroxide (H₂O₂). As C₃H₆O and H₂O₂ are the precursors of TATP, their ...detection is very important due to the high risk of the presence of TATP. In order to detect the precursors of TATP effectively, hierarchical molybdenum disulfide/reduced graphene oxide (MoS₂/RGO) composites were synthesized by a hydrothermal method, using two-dimensional reduced graphene oxide (RGO) as template. The effects of the ratio of RGO to raw materials for the synthesis of MoS₂ on the morphology, structure, and gas sensing properties of the MoS₂/RGO composites were studied. It was found that after optimization, the response to 50 ppm of H₂O₂ vapor was increased from 29.0% to 373.1%, achieving an increase of about 12 times. Meanwhile, all three sensors based on MoS₂/RGO composites exhibited excellent anti-interference performance to ozone with strong oxidation. Furthermore, three sensors based on MoS₂/RGO composites were fabricated into a simple sensor array, realizing discriminative detection of three target analytes in 14.5 s at room temperature. This work shows that the synergistic effect between two-dimensional RGO and MoS₂ provides new possibilities for the development of high performance sensors.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Inspired by the enhanced gas-sensing performance by the one-dimensional hierarchical structure, one-dimensional hierarchical polyaniline/multi-walled carbon nanotubes (PANI/CNT) fibers were prepared. ...Interestingly, the simple heating changed the sensing characteristics of PANI from p-type to n-type and n-type PANI and p-type CNTs form p-n hetero junctions at the core-shell interface of hierarchical PANI/CNT composites. The p-type PANI/CNT (p-PANI/CNT) and n-type PANI/CNT (n-PANI/CNT) performed the higher sensitivity to NO
and NH
, respectively. The response times of p-PANI/CNT and n-PANI/CNT to 50 ppm of NO
and NH
are only 5.2 and 1.8 s, respectively, showing the real-time response. The estimated limit of detection for NO
and NH
is as low as to 16.7 and 6.4 ppb, respectively. After three months, the responses of p-PANI/CNT and n-PANI/CNT decreased by 19.1% and 11.3%, respectively. It was found that one-dimensional hierarchical structures and the deeper charge depletion layer enhanced by structural changes of PANI contributed to the sensitive and fast responses to NH
and NO
. The formation process of the hierarchical PANI/CNT fibers, p-n transition, and the enhanced gas-sensing performance were systematically analyzed. This work also predicts the development prospects of cost-effective, high-performance PANI/CNT-based sensors.
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A simple solid-state chemical method was used for fabricating ZnS/graphene composites. The prepared samples were measured by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen ...adsorption-desorption, X-ray photoemission spectroscopy (XPS), ultraviolet–visible (UV–vis) absorption spectra, XPS-valance band spectroscopy, transient photocurrent response (PC), and photoluminescence (PL) spectra. The study shows that ZnS nanoparticles were well distributed on the graphene nanosheet in the composites, and the specific surface area enlarged when introducing graphene. The performances of the synthesized ZnS/graphene composites were assessed by the photocatalytic degradating methyl orange (MO). We found that the composites displayed excellent photocatalytic activity, and achieved 93% degradation within 120 min of UV irradiation. The impacts of graphene, NaBH4, and metallic salt and sulfide species on MO degradation were also investigated. Mechanism exploration found the excellent photocatalytic activity was attributed to high large specific surface area, strong oxidizability of active species, and the slow recombination of photoinduced carriers with the introduction of graphene. The band gap energy for the composites was 2.46 eV, suggesting the higher light absorption capacity. Transient photocurrent responses and photoluminescence spectra revealed a more efficient separation of the photoinduced charges for the composites. XPS-valance band spectroscopy and trapping experiments both verified that ·O2− played significant role in the degradation process.
•ZnS/graphene composites were synthesized by a simple solid-state chemical method.•Impacts of graphene, NaBH4, coupling ways, metallic salt and sulfide were studied.•The ZnS/graphene composites displayed superior photocatalytic activity to pure ZnS.•Well activity is due to surface area, strong oxidizability, and slow recombination.
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Abstract
The lowest-energy geometrical and electronic structures of Cu
38
cluster are investigated by density-functional calculations combined with a genetic algorithm based on a many body ...semi-empirical interatomic potential, the traditional FCC-truncated Octahedron (OH) and an incomplete-Mackay icosahedron (IMI) are recognized as the two lowest energy structures (energetically degenerate isomers) but with different electronic structures: a semiconductor-type with the energy-gap of 0.356 eV for the IMI and a metallic-type with negligible gap for the OH, which is in good agreement with the experimental results. The electron affinity and ionization potential of Cu
38
are also discussed and compared with the observations of the ultraviolet photoelectron spectroscopy experiments. The dynamical isomerization of the OH-like and IMI-like structures of Cu
38
is revealed to dominate the pre-melting stage through the investigation by the molecular dynamics annealing simulations.
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Plants can naturally interact with beneficial rhizobacteria to mediate defense responses against foliar pathogen infection. However, the mechanisms of rhizobacteria-mediated defense enhancement ...remain rarely clear. In this study, beneficial rhizobacterial strain
DN16 greatly increased the resistance of cucumber plants against
infection. RNA-sequencing analyses showed that several polyamine-associated genes including a thermospermine (TSpm) synthase gene (
) and polyamine catabolic genes (
,
, and
) were notably induced by DN16. The associations of TSpm metabolic pathways with the DN16-mediated cucumber defense responses were further investigated. The inoculated plants exhibited the increased leaf TSpm levels compared with the controls. Accordantly, overexpression of
in cucumber plants markedly increased leaf TSpm levels and enhanced defense against
infection. The functions of TSpm catabolism in the DN16-mediated defense responses of cucumber plants to
were further investigated by pharmacological approaches. Upon exposure to pathogen infection, the changes of leaf TSpm levels were positively related to the enhanced activities of polyamine catabolic enzymes including polyamine oxidases (PAOs) and copper amine oxidases (CuAOs), which paralleled the transcription of several defense-related genes such as pathogenesis-related protein 1 (
) and defensin-like protein 1 (
). However, the inhibited activities of polyamine catabolic enzymes abolished the DN16-induced cucumber defense against
infection. This was in line with the impaired expression of defense-related genes in the inoculated plants challenged by
. Collectively, our findings unraveled a pivotal role of TSpm catabolism in the regulation of the rhizobacteria-primed defense states by mediating the immune responses in cucumber plants after
infection.
Density functional theory is used to show that the adhesion between single-walled carbon nanotubes (SWNTs) and the catalyst particles from which they grow needs to be strong to support nanotube ...growth. It is found that Fe, Co, and Ni, commonly used to catalyze SWNT growth, have larger adhesion strengths to SWNTs than Cu, Pd, and Au and are therefore likely to be more efficient for supporting growth. The calculations also show that to maintain an open end of the SWNT it is necessary that the SWNT adhesion strength to the metal particle is comparable to the cap formation energy of the SWNT end. This implies that the difference between continued and discontinued SWNT growth to a large extent depends on the carbon−metal binding strength, which we demonstrate by molecular dynamics (MD) simulations. The results highlight that first principles computations are vital for the understanding of the binding strength's role in the SWNT growth mechanism and are needed to get accurate force field parameters for MD.
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The effects of the substitution of Fe by Co or Ni on both the structure and the magnetic properties of FeB amorphous alloy were investigated using first-principle molecular dynamics. The pair ...distribution function, Voronoi polyhedra, and density of states of Fe
TM
B
(x = 0, 10, 20, 30, and 40 at.%, TM(Transition Metal): Co, Ni) amorphous alloys were calculated. The results show that with the increase in Co content, the saturation magnetization of Fe
Co
B
(x = 0, 10, 20, 30, and 40 at.%) amorphous alloys initially increases and then decreases upon reaching the maximum at x = 10 at.%, while for Fe
Ni
B
(x = 0, 10, 20, 30, and 40 at.%), the saturation magnetization decreases monotonously with the increase in Ni content. Accordingly, for the two kinds of amorphous alloys, the obtained simulation results on the variation trends of the saturation magnetization with the change in alloy composition are in good agreement with the experimental observation. Furthermore, the relative maximum magnetic moment was recorded for Fe
Co
B
amorphous alloy, due to the induced increased magnetic moments of the Fe atoms surrounding the Co atom in the case of low Co dopant, as well as the increase in the exchange splitting energy caused by the enhancement of local atomic symmetry.
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To improve the separation efficiency of photogenerated carriers in ZnS, constructing a ZnS-based heterostructure with ZnO is assessed to be an efficient strategy, and a ZnO/ZnS photocatalyst was ...prepared by a solid-phase approach, and the structure and morphology were systematically studied. The ZnO/ZnS photocatalyst showed excellent photocatalytic properties on methyl orange, rhodamine B and tetracycline under UV light irradiation, indicating that the photocatalyst exhibited efficient broad-spectrum photocatalytic performance. Compared with ZnS, the degradation rates of ZnO/ZnS photocatalysts for methyl orange, rhodamine B and tetracycline under UV light increased from 21%, 9% and 32% to 96%, 94% and 93%, respectively, higher than the reported ZnO/ZnS composites synthesized by a novel wet chemical route, attributing to the improvement of light absorption ability and the effective separation of carriers. In addition, the influence of the sacrificial agent on the reaction system was investigated, and the synergistic mechanism of ZnO and ZnS in the catalytic process was analyzed according to the fluorescence spectra, photocurrent and first-principles calculation results, and a possible catalytic mechanism was put forward.
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•The ground state structure of FenPt (n = 3-13) clusters is investigated.•The results show that the magnetic moment results are the same regardless of the presence or absence of spin–orbit ...coupling.•The MAE of FenPt (n = 3, 4, 9,13) ranges from 1.420 to 2.687 meV/atom. The MAE was analyzed using the spin–orbit coupling matrix.
Enthusiasm for exploring magnetic anisotropy energy (MAE) and spin–orbit coupling (SOC) effects in magnetic studies of transition metal alloy clusters remains high. In this paper, the first-principle method was used to investigate the global minimum energy structure of FenPt (n = 3–13) clusters and their interesting magnetic properties. Comparative structural analyses show that FenPt (n = 3–13) clusters have unique structures, and their relative stability analyses indicate that the increase in the number of atoms influences the geometrical arrangement of the clusters. The exploration of magnetic properties has focused on two areas. First, FenPt (n = 3–13) is found to have a large magnetic moment, while the magnetic moment increment surprisingly varies in the same way in different cases with and without the inclusion of SOC effects. Second, the calculations show that FenPt (n = 3, 4, 9, 13) has MAE, ranging from 1.420-2.687 meV/atom. The SOC matrix results show the interaction of Pt dx2-y2 and Pt dxy, and the interaction of Pt dz2 and Pt dyz, exhibit an indispensable force in determining the MAE.
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