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1.
Artigo em Inglês | MEDLINE | ID: mdl-32052958

RESUMO

Heterostructures composed of superconductor and ferroelectrics (SC/FE) are very important for manipulating the superconducting property and applications. However, growth of high quality superconducting iron chalcogenide films is challenging due to their volatility and FE substrate with rough surface and large lattice mismatch. Here we report a two-step growth approach to get high quality FeSe0.5Te0.5 (FST) films on ferroelectric Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) with large lattice mismatch, which show superconductivity at only around 10 nm. Through systematic study of structural and electric transport properties of samples with different thicknesses, the mechanism is uncovered for this approach to grow high quality FST. Moreover, electric-field-induced remarkable change of Tc (superconducting transition temperature) is demonstrated in 20 nm FST film. This work paves the way to grow high quality films which contain volatile element and have large lattice mismatch with substrate. It is also helpful for manipulating the superconducting property in SC/FE heterostructures.

2.
J Am Chem Soc ; 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-32023049

RESUMO

The design of catalysts with high activity and robust stability for alkaline hydrogen evolution reaction (HER) remains a great challenge. Here, we report an efficient catalyst of two-dimensional bimetallene hydrides, in which H atoms stabilize the rhodium palladium bimetallene. The system exists because of the introduction of H that is in situ chemically released from the formaldehyde solution during the synthesis. This provides a highly stable catalyst based on an unstable combination of metal elements. Density functional theory calculations show the H is confined by electronic interactions and the Miedema rule of reverse stability of the RhPd alloy. The obtained catalyst exhibits outstanding alkaline HER catalytic performance with a low overpotential of 40 mV at 10 mA cm-2 and remarkable stability for over 10 h at 100 mA cm-2. The experimental results show that the confined H improve the activity, while the ultrathin sheet-like morphology yields stability. Our work provides guidance for synthesizing high-activity catalysts by confining heteroatoms into the crystal lattice of bimetallene and also a very novel mechanism for the growth of bimetallene made of highly immiscible components.

3.
Sensors (Basel) ; 20(1)2020 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-31947858

RESUMO

Deep learning-based image super-resolution has shown significantly good performance in improving image quality. In this paper, the RGB-IR cross input and sub-pixel upsampling network is proposed to increase the spatial resolution of an Infrared (IR) image by combining it with a color image of higher spatial resolution obtained with a different imaging modality. Specifically, this is accomplished by fusion of the features map of two RGB-IR inputs in the reconstruction of an infrared image. To improve the accuracy of feature extraction, deconvolution is replaced by sub-pixel convolution to upsample image in the network. Then, the guided filter layer is introduced for image denoising of IR images, and it can preserve the image detail. In addition, the experimental dataset, which is collected by us, contains large numbers of RGB images and corresponding IR images with the same scene. Experimental results on our dataset and other datasets demonstrate that the method is superior to existing methods in accuracy and visual improvement.

4.
Anal Chem ; 92(4): 3373-3379, 2020 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-31941278

RESUMO

Single-atom nanozymes (SAzymes), as novel nanozymes with atomically dispersed active sites, are of great importance in the development of nanozymes for their high catalytic activities, the maximum utilization efficiency of metal atoms, and the simple model of active sites. Herein, the peroxidase-like SAzymes with high-concentration Cu sites on carbon nanosheets (Cu-N-C) were synthesized through a salt-template strategy. With the densely distributed active Cu atoms (∼5.1 wt %), the Cu-N-C SAzymes exhibit remarkable activity to mimic natural peroxidase. Integrating Cu-N-C SAzymes with natural acetylcholinesterase and choline oxidase, three-enzyme-based cascade reaction system was constructed for the colorimetric detection of acetylcholine and organophosphorus pesticides. This work not only provides a strategy to synthesize SAzymes with abundant active sites but also gives some new insights for robust nanozyme biosensing systems.

5.
Adv Mater ; : e1906499, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31957134

RESUMO

As unique building blocks for next-generation optoelectronics, high-quality 2D p-n junctions based on semiconducting transition metal dichalcogenides (TMDs) have attracted wide interest, which are urgent to be exploited. Herein, a novel and facile electron doping of WSe2 by cetyltrimethyl ammonium bromide (CTAB) is achieved for the first time to form a high-quality intramolecular p-n junction with superior optoelectronic properties. Efficient manipulation of charge carrier type and density in TMDs via electron transfer between Br- in CTAB and TMDs is proposed theoretically by density functional theory (DFT) calculations. Compared with the intrinsic WSe2 photodetector, the switching light ratio (Ilight /Idark ) of the p-n junction device can be enhanced by 103 , and the temporal response is also dramatically improved. The device possesses a responsivity of 30 A W-1 , with a specific detectivity of over 1011 Jones. In addition, the mechanism of charge transfer in CTAB-doped 2D WSe2 and WS2 are investigated by designing high-performance field effect transistors. Besides the scientific insight into the effective manipulation of 2D materials by chemical doping, this work presents a promising applicable approach toward next-generation photoelectronic devices with high efficiency.

6.
Artigo em Inglês | MEDLINE | ID: mdl-31944499

RESUMO

Fully utilizing solar energy for catalysis requires integration of conversion mechanisms and therefore delicate design of catalyst structures and active species. Here, a MOF crystal engineering method was developed to controllably synthesize the copper-ceria catalyst with well-dispersed photoactive Cu-[O]-Ce species. Using preferential CO oxidation as a model reaction, the catalyst showed remarkably efficient and stable photoactivated catalysis, which found practical application in feed gas treatment for fuel cell gas supply. The coexistence of photochemistry and thermochemistry effects contributes to the high efficiency. Our results demonstrate a catalyst design approach with atomic or molecular precision and the combinatorial photoactivation strategy for solar energy conversion.

7.
Nat Commun ; 11(1): 132, 2020 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-31919355

RESUMO

Exploring advanced battery materials with fast charging/discharging capability is of great significance to the development of modern electric transportation. Herein we report a powerful synergistic engineering of carbon and deficiency to construct high-quality three/two-dimensional cross-linked Ti2Nb10O29-x@C composites at primary grain level with conformal and thickness-adjustable boundary carbon. Such exquisite boundary architecture is demonstrated to be capable of regulating the mechanical stress and concentration of oxygen deficiency for desired performance. Consequently, significantly improved electronic conductivity and enlarged lithium ion diffusion path, shortened activation process and better structural stability are realized in the designed Ti2Nb10O29-x@C composites. The optimized Ti2Nb10O29-x@C composite electrode shows fast charging/discharging capability with a high capacity of 197 mA h g-1 at 20 C (∼3 min) and excellent long-term durability with 98.7% electron and Li capacity retention over 500 cycles. Most importantly, the greatest applicability of our approach has been demonstrated by various other metal oxides, with tunable morphology, structure and composition.

8.
J Am Chem Soc ; 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31999446

RESUMO

Defect engineering is widely applied in transition metal dichalcogenides (TMDs) to achieve electrical, optical, magnetic, and catalytic regulation. Vacancies, regarded as a type of extremely delicate defect, are acknowledged to be effective and flexible in general catalytic modulation. However, the influence of vacancy states in addition to concentration on catalysis still remains vague. Thus, via high throughput calculations, the optimized sulfur vacancy (S-vacancy) state in terms of both concentration and distribution is initially figured out among a series of MoS2 models for the hydrogen evolution reaction (HER). In order to realize it, a facile and mild H2O2 chemical etching strategy is implemented to introduce homogeneously distributed single S-vacancies onto the MoS2 nanosheet surface. By systematic tuning of the etching duration, etching temperature, and etching solution concentration, comprehensive modulation of the S-vacancy state is achieved. The optimal HER performance reaches a Tafel slope of 48 mV dec-1 and an overpotential of 131 mV at a current density of 10 mA cm-2, indicating the superiority of single S-vacancies over agglomerate S-vacancies. This is ascribed to the more effective surface electronic structure engineering as well as the boosted electrical transport properties. By bridging the gap, to some extent, between precise design from theory and practical modulation in experiments, the proposed strategy extends defect engineering to a more sophisticated level to further unlock the potential of catalytic performance enhancement.

9.
ACS Appl Mater Interfaces ; 12(5): 6707-6715, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31927907

RESUMO

Interfaces between materials provide an intellectually rich arena for fundamental scientific discovery and device design. However, the frustration of magnetization and conductivity of perovskite oxide films under reduced dimensionality is detrimental to their device performance, preventing their active low-dimensional application. Herein, by inserting the ultrathin 4d ferromagnetic SrRuO3 layer between ferroelectric BaTiO3 layers to form a sandwich heterostructure, we observe enhanced physical properties in ultrathin SrRuO3 films, including longitudinal conductivity, Curie temperature, and saturated magnetic moment. Especially, the saturated magnetization can be enhanced to ∼3.12 µB/Ru in ultrathin BaTiO3/SrRuO3/BaTiO3 trilayers, which is beyond the theoretical limit of bulk value (2 µB/Ru). This observation is attributed to the synergistic ferroelectric proximity effect (SFPE) at upper and lower BaTiO3/SrRuO3 heterointerfaces, as revealed by the high-resolution lattice structure analysis. This SFPE in dual-ferroelectric interface cooperatively induces ferroelectric-like lattice distortions in RuO6 oxygen octahedra and subsequent spin-state crossover in SrRuO3, which in turn accounts for the observed enhanced magnetization. Besides the fundamental significance of interface-induced spin-lattice coupling, our findings also provide a viable route to the electrical control of magnetic ordering, taking a step toward low-power applications in all-oxide spintronics.

10.
Angew Chem Int Ed Engl ; 59(4): 1718-1726, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31799763

RESUMO

A challenging but pressing task to design and synthesize novel, efficient, and robust pH-universal hydrogen evolution reaction (HER) electrocatalysts for scalable and sustainable hydrogen production through electrochemical water splitting. Herein, we report a facile method to prepare an efficient and robust Ru-M (M=Ni, Mn, Cu) bimetal nanoparticle and carbon quantum dot hybrid (RuM/CQDs) for pH-universal HER. The RuNi/CQDs catalysts exhibit outstanding HER performance at all pH levels. The unexpected low overpotentials of 13, 58, and 18 mV shown by RuNi/CQDs allow a current density of 10 mA cm-2 in 1 m KOH, 0.5 m H2 SO4 , and 1 m PBS, respectively, for Ru loading at 5.93 µgRu cm-2 . This performance is among the best catalytic activities reported for any platinum-free electrocatalyst. Theoretical studies reveal that Ni doping results in a moderate weakening of the hydrogen bonding energy of nearby surface Ru atoms, which plays a critical role in improving the HER activity.

11.
ACS Appl Mater Interfaces ; 12(1): 1850-1857, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31816227

RESUMO

Phytic acid (PA), which is a natural and innoxious plant constituent, can strongly adsorb on the metal surface because of its six phosphate groups. In this work, based on the chelating properties of PA and the reaction between PA and hydrolyzable vinyltriethoxysilane (VTES), we developed a novel and facial strategy to generate hierarchical-layer nanospheres on the metal mesh surface and fabricated robust superhydrophobic and superoleophilic miniature metal mesh ships. Because of their superwetting properties, the modified meshes could easily remove and recycle the oil spills from the water surface (>90% collection efficiency), and have high oil/water separation capacity (>96%). The excellent stability, corrosion resistance, and robust mechanical durability endow the modified mesh ships with more advantages in a marine environment. We envision that these superhydrophobic meshes modified with PA and VTES are sustainable, environmentally friendly, and easy to scale up and hence display great potential in practical application.

12.
J Med Virol ; 92(3): 317-328, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31642539

RESUMO

BACKGROUND AND AIM: Hepatitis B virus (HBV) load and antigens are related to the innate and adaptive immunity of chronic hepatitis B (CHB) patients. As a new HBV biomarker, the role of pregenomic RNA (pgRNA) in host immunity is not known. This study aimed to identify the relationship between serum HBV pgRNA and host immunity in CHB patients. METHODS: Two hundred twenty-five treatment-naïve CHB patients were enrolled. Serum cytokines were measured by cytokine antibody array (Luminex multiplex platform). Th1 (T-helper cell, Th) and Th2 cells were tested by flow cytometry. Serum HBV pgRNA was detected by a reverse transcription-polymerase chain reaction. RESULTS: Serum HBV pgRNA was significantly different among patients in different disease phases and significantly associated with both HBV antigens and antibodies. Serum HBV pgRNA was positively correlated with the HBsAg level (P < .001) and the presence of HBeAg (P < .001). Patients with higher HBcAb levels showed lower serum HBV pgRNA levels (P = .003). Notably, HBsAb positivity was associated with higher levels of serum HBV pgRNA in HBeAg(-) patients (P = .049). Serum HBV pgRNA was positively associated with ALT level, Th2 cell frequency, and related cytokine sCD30 (P < .001, P < .001, and P = .003, respectively), but negatively associated with Th1-related cytokine interleukin (IL)-12P70 and cytotoxic lymphocytes (CTLs) (P = .017 and P < .001, respectively). CONCLUSION: Our study confirmed the relationship between serum HBV pgRNA and host immunity. The results demonstrated that serum HBV pgRNA is positively correlated with Th2 immunity but negatively correlated with Th1 immunity, indicating that it might have a relationship with HBV antigen conversion and CTL immunodeficiency in CHB patients.

13.
Angew Chem Int Ed Engl ; 59(3): 1216-1219, 2020 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-31691469

RESUMO

Direct conversion of methane to value-added chemicals with high selectivity under mild conditions remains a great challenge in catalysis. Now, single chromium atoms supported on titanium dioxide nanoparticles are reported as an efficient heterogeneous catalyst for direct methane oxidation to C1 oxygenated products with H2 O2 as oxidant under mild conditions. The highest yield for C1 oxygenated products can be reached as 57.9 mol molCr -1 with selectivity of around 93 % at 50 °C for 20 h, which is significantly higher than those of most reported catalysts. The superior catalytic performance can be attributed to the synergistic effect between single Cr atoms and TiO2 support. Combining catalytic kinetics, electron paramagnetic resonance, and control experiment results, the methane conversion mechanism was proposed as a methyl radical pathway to form CH3 OH and CH3 OOH first, and then the generated CH3 OH is further oxidized to HOCH2 OOH and HCOOH.

14.
Adv Mater ; 32(2): e1906646, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31743525

RESUMO

Ultrathin molybdenum disulfide (MoS2 ) presents ideal properties for building next-generation atomically thin circuitry. However, it is difficult to construct logic units of MoS2 monolayer using traditional silicon-based doping schemes, such as atomic substitution and ion implantation, as they cause lattice disruption and doping instability. An accurate and feasible electronic structure modulation strategy from defect engineering is proposed to construct homogeneous electronics for MoS2 monolayer logic inverters. By utilizing the energy-matched electron induction of the solution process, numerous pure and lattice-stable monosulfur vacancies (Vmonos ) are introduced to modulate the electronic structure of monolayer MoS2 via a shallow trapping effect. The resulting modulation effectively reduces the electronic concentration of MoS2 and improves the work function by 100 meV. Under modulation of Vmonos , an atomically thin homogenous monolayer MoS2 logic inverter with a voltage gain of 4 is successfully constructed. A brand-new and practical design route of defect modulation for 2D-based circuit development is provided.

15.
Angew Chem Int Ed Engl ; 59(2): 721-724, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31622001

RESUMO

Precise control of the micro-/nanostructures of nanomaterials, such as hollow multi-shelled structures (HoMSs), has shown its great advantages in various applications. Now, the crystal structure of building blocks of HoMSs are controlled by introducing the lattice distortion in HoMSs, for the first time. The lattice distortion located at the nanoscale interface of SnS2 /SnO2 can provide additional active sites, which not only provide the catalytic activity under visible light but also improve the separation of photoexcited electron-hole pairs. Combined with the efficient light utilization, the natural advantage of HoMSs, a record catalytic activity was achieved in solid-gas system for CO2 reduction, with an excellent stability and 100 % CO selectivity without using any sensitizers or noble metals.

16.
Angew Chem Int Ed Engl ; 59(1): 232-236, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31609053

RESUMO

Traditional methods for analyzing organophosphorus pesticide chlorpyrifos, usually require the tedious sample pretreatment and sophisticated bio-interfaces, leading to the difficulty for real-time analysis. Herein, we use palladium single-atom (PdSA)/TiO2 as a photocatalytic sensing platform to directly detect chlorpyrifos with high sensitivity and selectivity. PdSA/TiO2 , prepared by an in situ photocatalytic reduction of PdCl4 2- on the TiO2 , shows much higher photocatalytic activity (10 mol g-1 h-1 ) for hydrogen evolution reaction than Pd nanoparticles (1.95 mol g-1 h-1 ), and excellent stability. In the presence of chlorpyrifos, the photocatalytic activity of PdSA/TiO2 decreases. Through this inhibition effect the platform can realize a detection limit for chlorpyrifos of 0.01 ng mL-1 , much lower than the maximum residue limit (10 ppb) permitted by the U.S. Environmental Protection Agency.

17.
Angew Chem Int Ed Engl ; 59(3): 1295-1301, 2020 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-31654544

RESUMO

It is highly desirable but challenging to optimize the structure of photocatalysts at the atomic scale to facilitate the separation of electron-hole pairs for enhanced performance. Now, a highly efficient photocatalyst is formed by assembling single Pt atoms on a defective TiO2 support (Pt1 /def-TiO2 ). Apart from being proton reduction sites, single Pt atoms promote the neighboring TiO2 units to generate surface oxygen vacancies and form a Pt-O-Ti3+ atomic interface. Experimental results and density functional theory calculations demonstrate that the Pt-O-Ti3+ atomic interface effectively facilitates photogenerated electrons to transfer from Ti3+ defective sites to single Pt atoms, thereby enhancing the separation of electron-hole pairs. This unique structure makes Pt1 /def-TiO2 exhibit a record-level photocatalytic hydrogen production performance with an unexpectedly high turnover frequency of 51423 h-1 , exceeding the Pt nanoparticle supported TiO2 catalyst by a factor of 591.

18.
ACS Nano ; 14(1): 1102-1110, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31887009

RESUMO

Owing to its unique structure, Chevrel phase (CP) is a promising candidate for applications in rechargeable multivalent (Mg and Al) batteries. However, its wide applications are severely limited by time-consuming and complex synthesis processes, accompanied by uncontrollable growth and large particle sizes, which will magnify the charge trapping effect and lower the electrochemical performance. Here, an iodine vapor transport reaction (IVT) is proposed to obtain large-scale and highly pure Mo6S8 nanosheets, in which iodine helps to regulate the growth kinetics and induce the preferential growth of Mo6S8, as a typical three-dimensional material, to form nanosheets. When applied in rechargeable multivalent (Mg and Al) batteries, Mo6S8 nanosheets show very fast kinetics owing to the short diffusion distance, thereby exhibiting lower polarization, higher capacities, and better low-temperature performance (up to -40 °C) compared to that of microparticles obtained via the conventional method. It is anticipated that Mo6S8 nanosheets would boost the application of Chevrel phase, especially in areas of energy storage and catalysis, and the IVT reaction would be generalized to a wide range of inorganic compound nanosheets.

19.
Adv Mater ; 32(7): e1904249, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31880031

RESUMO

The development of highly efficient photocatalytic systems with rapid photogenerated charge separation and high surface catalytic activity is highly desirable for the storage and conversion of solar energy, yet remains a grand challenge. Herein, a conceptionally new form of atomically dispersed Co-P3 species on CdS nanorods (CoPSA-CdS) is designed and synthesized for achieving unprecedented photocatalytic activity for the dehydrogenation of formic acid (FA) to hydrogen. X-ray absorption near edge structure, X-ray photoelectron spectroscopy, and time-resolved photoluminescence results confirm that the Co-P3 species have a unique electron-rich feature, greatly improving the efficiency of photogenerated charge separation through an interface charge effect. The in situ attenuated total reflection infrared spectra reveal that the Co-P3 species can achieve much better dissociation adsorption of FA and activation of CH bonds than traditional sulfur-coordinated Co single atom-loaded CdS nanorods (CoSSA-CdS). These two new features make CoPSA-CdS exhibit the unprecedented 50-fold higher activity in the photocatalytic dehydrogenation of FA than CoSSA-CdS, and also much better activity than the Ru-, Rh-, Pd-, or Pt-loaded CdS. Besides, CoPSA-CdS also shows the highest mass activity (34309 mmol gCo -1 h-1 ) of Co reported to date. First-principles simulation reveals that the Co-P3 species herein can form an active PHCOO intermediate for enhancing the rate-determining dissociation adsorption of FA.

20.
Cancer Manag Res ; 11: 10029-10039, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31819635

RESUMO

Purpose: We aim to construct a nomogram to predict breast cancer survival and guide postoperative adjuvant chemotherapy in China. Patients and methods: A total of 5,504 breast cancer patients from the Tianjin Breast Cancer Cases Cohort were included. Multivariable Cox regression was used to investigate the factors associated with overall survival (OS) and a nomogram was constructed based on these prognostic factors. The nomogram was internal and external validated and the performance was evaluated by area under the curve (AUC) and calibration curve. The partial score was also constructed and stratified them into low, moderate and high-risk subgroups for death according to the tripartite grouping method. Multivariate Cox regression analysis and the propensity score matching method were respectively used to test the association between adjuvant chemotherapy and OS in different risk subgroups. Results: Age, diameter, histological differentiation, lymph node metastasis, estrogen, and progesterone receptor were incorporated into the nomogram and validation results showed this nomogram was well-calibrated to predict the 3-year [AUC =74.1%; 95% confidence interval (CI): 70.1-78.0%] and 5-year overall survival [AUC =72.3%; 95% CI: 69.6-75.1%]. Adjuvant chemotherapy was negatively associated with death in high risk subgroup [Hazard Ratio (HR) = 0.54; 95% CI: 0.37-0.77; P<0.001]. However, no significant association were found in groups with low (HR=1.47; 95% CI: 0.52-4.19; P=0.47) and moderate risk (HR=0.78; 95% CI: 0.42-1.48; P=0.45). The 1:1 PSM generated 822 pairs of well-matched patients and Kaplan-Meier showed the high-risk patients could benefit from chemotherapy, whereas low risk and moderate risk subjects did not appear to benefit from chemotherapy. Conclusion: Not all of the breast cancer patients benefit equally from chemotherapy. The nomogram could be used to evaluate the overall survival of breast cancer patients and predict the magnitude of benefit and guide adjuvant chemotherapy for breast cancer patients after surgery.

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