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1.
Nanoscale Res Lett ; 14(1): 213, 2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31240467

RESUMO

In this work, three-dimensional (3D) CoMoSe4 nanosheet arrays on network fibers of a carbon cloth denoted as CoMoSe4@C converted directly from CoMoO4 nanosheet arrays prepared by a hydrothermal process followed by the plasma-assisted selenization at a low temperature of 450 °C as an anode for sodium-ion battery (SIB) were demonstrated for the first time. With the plasma-assisted treatment on the selenization process, oxygen (O) atoms can be replaced by selenium (Se) atoms without the degradation on morphology at a low selenization temperature of 450 °C. Owing to the high specific surface area from the well-defined 3D structure, high electron conductivity, and bi-metal electrochemical activity, the superior performance with a large sodium-ion storage of 475 mA h g-1 under 0.5-3 V potential range at 0.1 A g-1 was accomplished by using this CoMoSe4@C as the electrode. Additionally, the capacity retention was well maintained over 80 % from the second cycle, exhibiting a satisfied capacity of 301 mA h g-1 even after 50 cycles. The work delivered a new approach to prepare a binary transition metallic selenide and definitely enriches the possibilities for promising anode materials in SIBs with high performances.

2.
Nanoscale ; 11(21): 10410-10419, 2019 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31112143

RESUMO

Utilization of light to boost the performance of gas sensors allows us to operate sensor devices at room temperature. Here, we, for the first time, demonstrated an indoor light-activated 3D cone-shaped MoS2 bilayer-based NO gas sensor with ppb-level detection operated at room-temperature. Large-area cone-shaped (CS)-MoS2 bilayers were grown by depositing 2 nm-thick MoO3 layers on a 2'' three-dimensional (3D) cone-patterned sapphire substrate (CPSS) followed by a sulfurization process via chemical vapor deposition. Because the exposed area of MoS2 bilayers is increased by 30%, the CS-MoS2 gas sensor (GS) demonstrated excellent performance with a response of ∼470% and a fast response time of ∼25 s after exposure to 1 ppm of NO gas illuminated by ultraviolet (UV) light with a wavelength of 365 nm. Such extraordinary performance at room temperature is attributed to the enhanced light absorption because of the light scattering effect caused by the 3D configuration and photo-desorption induced by UV illumination. For NO concentrations ranging from 2 ppm down to 0.06 ppm, the CS-MoS2 GS demonstrated a stable sensing behavior with a high response and fast response time (470% and 25 s at 2 ppm NO) because of the light absorption enhanced by the 3D structure and photo-desorption under constant UV illumination. The CS-MoS2 GS exhibits a high sensitivity (∼189.2 R% ppm-1), allowing the detection of NO gas at 0.06 ppm in 130 s. In addition, the 3D cone-shaped structure prolonged the presence of sulfur vapor around MoO3, allowing MoO3 to react with sulfur completely. Furthermore, the CS-MoS2 GS using an indoor lighting to detect NO gas at room temperature was demonstrated for the first time where the CS-MoS2 GS exhibits a stable cycling behavior with a high response (165% at 1 ppm NO) in 50 s; for concentration as low as ∼0.06 ppm, the response of ∼75% in 150 s can be achieved.

3.
Nanoscale Res Lett ; 13(1): 242, 2018 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-30120632

RESUMO

Few-layer graphene sheet-passivated porous silicon (PSi) as an outstanding electrochemical double-layer supercapacitor electrode was demonstrated. The PSi matrix was formed by electrochemical etching of a doped silicon wafer and was further surface-passivated with few-layer graphene sheets by a Ni-assisted chemical vapor deposition process where a wide range of porous PSi structures, including mesoporous, macroporous, and hybrid porous structures were created during the graphene growth as temperature increases. The microstructural and graphene-passivation effects on the capacitive performance of the PSi were investigated in detail. The hybrid porous PSi electrode, optimized in terms of capacitive performances, achieves a high areal capacitance of 6.21 mF/cm2 at an ultra-high scan rate of 1000 mV/s and an unusual progressing cyclic stability of 131% at 10,000 cycles. Besides mesopores and macropores, micropores were introduced onto the surfaces of the passivating few-layer graphene sheets with a KOH activation process to further increase the functioning surface area of the hierarchical porous PSi electrode, leading to a boost in the areal capacitance by 31.4% up to 8.16 mF/cm2. The present designed hierarchical porous PSi-based supercapacitor proves to be a robust energy storage device for microelectronic applications that require stable high rate capability.

4.
ACS Appl Mater Interfaces ; 10(41): 35477-35486, 2018 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-30107132

RESUMO

Selenium (Se) is one of the potential candidates as photodetector because of its outstanding properties such as high photoconductivity (∼8 × 104 S cm-1), piezoelectricity, thermoelectricity, and nonlinear optical responses. Solution phase synthesis becomes an efficient way to produce Se, but a contamination issue that could deteriorate the electric characteristic of Se should be taken into account. In this work, a facile, controllable approach of synthesizing Se nanowires (NWs)/films via a plasma-assisted growth process was demonstrated at the low substrate temperature of 100 °C. The detailed formation mechanisms of nanowires arrays to thin films at different plasma powers were investigated. Moreover, indium (In) layer was used to enhance the adhesive strength with 50% improvement on a SiO2/Si substrate by mechanical interlocking and surface alloying between Se and In layers, indicating great tolerance for mechanical stress for future wearable devices applications. Furthermore, the direct growth of Se NWs/films on a poly(ethylene terephthalate) substrate was demonstrated, exhibiting a visible to broad infrared detection ranges from 405 to 1555 nm with a high on/off ratio of ∼700 as well as the fast response time less than 25 ms. In addition, the devices exhibited fascinating stability in the atmosphere over one month.

5.
Small ; 14(22): e1704052, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29707890

RESUMO

Phase-engineered type-II metal-selenide heterostructures are demonstrated by directly selenizing indium-tin oxide to form multimetal selenides in a single step. The utilization of a plasma system to assist the selenization facilitates a low-temperature process, which results in large-area films with high uniformity. Compared to single-metal-selenide-based photodetectors, the multimetal-selenide photodetectors exhibit obviously improved performance, which can be attributed to the Schottky contact at the interface for tuning the carrier transport, as well as the type-II heterostructure that is beneficial for the separation of the electron-hole pairs. The multimetal-selenide photodetectors exhibit a response to light over a broad spectrum from UV to visible light with a high responsivity of 0.8 A W-1 and an on/off current ratio of up to 102 . Interestingly, all-transparent photodetectors are successfully produced in this work. Moreover, the possibility of fabricating devices on flexible substrates is also demonstrated with sustainable performance, high strain tolerance, and high durability during bending tests.

6.
Small ; 14(19): e1800032, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29635730

RESUMO

The formation of PtSe2 -layered films is reported in a large area by the direct plasma-assisted selenization of Pt films at a low temperature, where temperatures, as low as 100 °C at the applied plasma power of 400 W can be achieved. As the thickness of the Pt film exceeds 5 nm, the PtSe2 -layered film (five monolayers) exhibits a metallic behavior. A clear p-type semiconducting behavior of the PtSe2 -layered film (≈trilayers) is observed with the average field effective mobility of 0.7 cm2 V-1 s-1 from back-gated transistor measurements as the thickness of the Pt film reaches below 2.5 nm. A full PtSe2 field effect transistor is demonstrated where the thinner PtSe2 , exhibiting a semiconducting behavior, is used as the channel material, and the thicker PtSe2 , exhibiting a metallic behavior, is used as an electrode, yielding an ohmic contact. Furthermore, photodetectors using a few PtSe2 -layered films as an adsorption layer synthesized at the low temperature on a flexible substrate exhibit a wide range of absorption and photoresponse with the highest photocurrent of 9 µA under the laser wavelength of 408 nm. In addition, the device can maintain a high photoresponse under a large bending stress and 1000 bending cycles.

7.
Oncol Lett ; 15(2): 2153-2160, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29434919

RESUMO

Serine/threonine kinase 33 (STK33) is a novel protein that has been the focus of an increasing number of studies in recent years; however, the role of STK33 in tumorigenesis remains controversial. Previous studies have demonstrated that STK33 is overexpressed in several human cancers and exerts a pro-tumorigenic effect through the promotion of cell proliferation. However, the role of STK33 in colorectal cancer (CRC), which is one of the most aggressive human malignancies, remains unclear. The aim of the current study was to investigate the methylation status of STK33 in CRC and to determine its clinical significance. The results demonstrated that STK33 was hypermethylated in CRC cell lines and promoted the proliferation of CRC cells. In addition, the methylation status and expression of STK33 in 94 pairs of cancer and noncancerous tissues obtained from patients with CRC was investigated. STK33 methylation was significantly increased in cancer tissues when compared with adjacent noncancerous tissues (P<0.001). STK33 methylation was associated with lymph node metastasis (P<0.05), tumor invasion (P<0.05), distant metastases (P<0.01) and tumor stage (P<0.01). Reduced STK33 mRNA and protein expression in CRC was associated with STK33 hypermethylation (P<0.001). In addition, patients with hypermethylated STK33 exhibited shorter overall survival rates when compared with those with unmethylated STK33 (P<0.01). In conclusion, the results of the current study suggest that STK33 hypermethylation may be a promising novel biomarker for the diagnosis, prognosis and suitable treatment of CRC.

8.
ACS Appl Mater Interfaces ; 10(11): 9645-9652, 2018 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-29309121

RESUMO

Direct reduction of metal oxides into a few transition metal dichalcogenide (TMDCs) monolayers has been recently explored as an alternative method for large area and uniform deposition. However, not many studies have addressed the characteristics and requirement of the metal oxides into TMDCs by the selenization/sulfurization processes, yielding a wide range of outstanding properties to poor electrical characteristics with nonuniform films. The large difference implies that the process is yet not fully understood. In particular, the selenization/sulfurization at low temperature leads to poor crystallinity films with poor electrical performance, hindering its practical development. A common approach to improve the quality of the selenized/sulfurized films is by further increasing the process temperature, thus requiring additional transfer in order to explore the electrical properties. Here, we show that by finely tuning the quality of the predeposited oxide the selenization/sulfurization temperature can be largely decreased, avoiding major substrate damage and allowing direct device fabrication. The direct relationship between the role of selecting different metal oxides prepared by e-beam evaporation and reactive sputtering and their oxygen deficiency/vacancy leading to quality influence of TMDCs was investigated in detail. Because of its outstanding physical properties, the formation of tungsten diselenide (WSe2) from the reduction of tungsten oxide (WO x) was chosen as a model for proof of concept. By optimizing the process parameters and the selection of metal oxides, layered WSe2 films with controlled atomic thickness can be demonstrated. Interestingly, the domain size and electrical properties of the layered WSe2 films are highly affected by the quality of the metal oxides, for which the layered WSe2 film with small domains exhibits a metallic behavior and the layered WSe2 films with larger domains provides clear semiconducting behavior. Finally, an 8'' wafer scale-layered WSe2 film was demonstrated, giving a step forward in the development of 2D TMDC electronics in the industry.

9.
Sci Adv ; 3(3): e1602557, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28378017

RESUMO

There is great interest in developing a low-power gas sensing technology that can sensitively and selectively quantify the chemical composition of a target atmosphere. Nanomaterials have emerged as extremely promising candidates for this technology due to their inherent low-dimensional nature and high surface-to-volume ratio. Among these, nanoscale silicon is of great interest because pristine silicon is largely inert on its own in the context of gas sensing, unless functionalized with an appropriate gas-sensitive material. We report a chemical-sensitive field-effect transistor (CS-FET) platform based on 3.5-nm-thin silicon channel transistors. Using industry-compatible processing techniques, the conventional electrically active gate stack is replaced by an ultrathin chemical-sensitive layer that is electrically nonconducting and coupled to the 3.5-nm-thin silicon channel. We demonstrate a low-power, sensitive, and selective multiplexed gas sensing technology using this platform by detecting H2S, H2, and NO2 at room temperature for environment, health, and safety in the oil and gas industry, offering significant advantages over existing technology. Moreover, the system described here can be readily integrated with mobile electronics for distributed sensor networks in environmental pollution mapping and personal air-quality monitors.

10.
ACS Appl Mater Interfaces ; 9(16): 14006-14012, 2017 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-28281352

RESUMO

Ink-printing method emerges as a viable way for manufacturing large-scale flexible Cu(In,Ga)Se2 (CIGS) thin film photovoltaic (TFPV) devices owing to its potential for the rapid process, mass production, and low-cost nonvacuum device fabrication. Here, we brought the femtosecond laser annealing (fs-LA) process into the ink-printing CIGS thin film preparation. The effects of fs-LA treatment on the structural and optoelectronic properties of the ink-printing CIGS thin films were systematically investigated. It was observed that, while the film surface morphology remained essentially unchanged under superheating, the quality of crystallinity was significantly enhanced after the fs-LA treatment. Moreover, a better stoichiometric composition was achieved with an optimized laser scanning rate of the laser beam, presumably due to the much reduced indium segregation phenomena, which is believed to be beneficial in decreasing the defect states of InSe, VSe, and InCu. Consequently, the shunt leakage current and recombination centers were both greatly decreased, resulting in a near 20% enhancement in photovoltaic conversion efficiency.

11.
Oncol Rep ; 37(4): 1961-1970, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28259923

RESUMO

Epithelial-mesenchymal transition (EMT) is a critical step in the acquisition of metastatic and invasive power for tumor cells. Colorectal adenocarcinoma (CRC) is a common cancer where metastasis is directly linked to patient survival. Recent studies show that pleomorphic adenoma gene like-2 (PLAGL2) could induce tumor EMT and is an independent predictive factor associated with poor prognosis in cancer. In the present study, we confirmed the role of PLAGL2 in the prognosis of CRC patients and provide molecular evidence of PLAGL2 promoted EMT in CRC cell line SW480. We found that PLAGL2 expression was upregulated in the paraffin-embedded CRC tissues compared to borderline or benign tissues. Experimental EMT induced by PLAGL2 plasmid transfection proved PLAGL2 protein overexpression could enhance the cell scratch wound-healing and transwell ability and significantly upregulated mesenchymal marker proteins, N-cadherin and vimentin and concurrently downregulated epithelial marker of E-cadherin. Subsequently, through western blot assay, we found that PLAGL2 could activate the wnt-signaling component ß-catenin in the nuclei. More CRC cell metastasis to the lungs was observed when the PLAGL2 overexpressing SW480 cells were injected into the tail vein of rats, compared with the cell control and PLAGL2 silence group. Our findings indicated that PLAGL2 might be a very upstream key molecule regulating EMT involved in Wnt/ß­catenin signaling pathway.


Assuntos
Adenocarcinoma/genética , Neoplasias Colorretais/genética , Proteínas de Ligação a DNA/genética , Transição Epitelial-Mesenquimal/genética , Proteínas de Ligação a RNA/genética , Fatores de Transcrição/genética , Adenocarcinoma/patologia , Idoso , Idoso de 80 Anos ou mais , Animais , Linhagem Celular Tumoral , Movimento Celular/genética , Neoplasias Colorretais/patologia , Proteínas de Ligação a DNA/biossíntese , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Proteínas de Ligação a RNA/biossíntese , Ratos , Fatores de Transcrição/biossíntese , Vimentina/genética , Via de Sinalização Wnt/genética , Ensaios Antitumorais Modelo de Xenoenxerto , beta Catenina/genética
12.
Sci Rep ; 6: 19102, 2016 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-26902556

RESUMO

The use of costly and rare metals such as indium and gallium in Cu(In,Ga)Se2 (CIGS) based solar cells has motivated research into the use of Cu2ZnSnS4 (CZTS) as a suitable replacement due to its non-toxicity, abundance of compositional elements and excellent optical properties (1.5 eV direct band gap and absorption coefficient of ~10(4) cm(-1)). In this study, we demonstrate a one-step pulsed hybrid electrodeposition method (PHED), which combines electrophoretic and electroplating deposition to deposit uniform CZTS thin-films. Through careful analysis and optimization, we are able to demonstrate CZTS solar cells with the VOC, JSC, FF and η of 350 mV, 3.90 mA/cm(2), 0.43 and 0.59%, respectively.

13.
Nano Lett ; 16(4): 2463-70, 2016 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-26906714

RESUMO

Although chemical vapor deposition is the most common method to synthesize transition metal dichalcogenides (TMDs), several obstacles, such as the high annealing temperature restricting the substrates used in the process and the required transfer causing the formation of wrinkles and defects, must be resolved. Here, we present a novel method to grow patternable two-dimensional (2D) transition metal disulfides (MS2) directly underneath a protective coating layer by spin-coating a liquid chalcogen precursor onto the transition metal oxide layer, followed by a laser irradiation annealing process. Two metal sulfides, molybdenum disulfide (MoS2) and tungsten disulfide (WS2), are investigated in this work. Material characterization reveals the diffusion of sulfur into the oxide layer prior to the formation of the MS2. By controlling the sulfur diffusion, we are able to synthesize continuous MS2 layers beneath the top oxide layer, creating a protective coating layer for the newly formed TMD. Air-stable and low-power photosensing devices fabricated on the synthesized 2D WS2 without the need for a further transfer process demonstrate the potential applicability of TMDs generated via a laser irradiation process.

14.
Adv Mater ; 28(13): 2547-54, 2016 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-26833783

RESUMO

Monolithic 3D integrated circuits using transition metal dichalcogenide materials and low-temperature processing are reported. A variety of digital and analog circuits are implemented on two sequentially integrated layers of devices. Inverter circuit operation at an ultralow supply voltage of 150 mV is achieved, paving the way to high-density, ultralow-voltage, and ultralow-power applications.

15.
Nat Commun ; 7: 10502, 2016 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-26813257

RESUMO

The III-V compound semiconductors exhibit superb electronic and optoelectronic properties. Traditionally, closely lattice-matched epitaxial substrates have been required for the growth of high-quality single-crystal III-V thin films and patterned microstructures. To remove this materials constraint, here we introduce a growth mode that enables direct writing of single-crystalline III-V's on amorphous substrates, thus further expanding their utility for various applications. The process utilizes templated liquid-phase crystal growth that results in user-tunable, patterned micro and nanostructures of single-crystalline III-V's of up to tens of micrometres in lateral dimensions. InP is chosen as a model material system owing to its technological importance. The patterned InP single crystals are configured as high-performance transistors and photodetectors directly on amorphous SiO2 growth substrates, with performance matching state-of-the-art epitaxially grown devices. The work presents an important advance towards universal integration of III-V's on application-specific substrates by direct growth.

16.
Phys Chem Chem Phys ; 17(33): 21389-93, 2015 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-26220549

RESUMO

Germanene layers with lonsdaleite structure has been synthesized from a SiGe thin film for the first time using a N2 plasma-assisted process in this investigation. Multi-layered germanene can be directly observed, and the derived lattice parameters are nearly consistent with the theoretical results. Furthermore, large-scale multi-layered germanene has also been demonstrated for applications.

17.
Small ; 11(33): 4117-22, 2015 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-26034015

RESUMO

Epitaxial core-shell CoO-CoFe2 O4 nanocrystals are fabricated by using pulsed laser deposition with the aid of melted material (Bi2 O3 ) addition and suitable lattice mismatch provided by substrates (SrTiO3 ). Well aligned orientations among nanocrystals and reversible core-shell sequence reveal tunable magnetic anisotropy. The interfacial coupling between core and shell further engineers the nanocrystal functionality.

18.
ACS Nano ; 9(4): 4346-53, 2015 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-25768931

RESUMO

Recently, a few attempts to synthesize monolayers of transition metal dichalcogenides (TMDs) using the chemical vapor deposition (CVD) process had been demonstrated. However, the development of alternative processes to synthesize TMDs is an important step because of the time-consuming, required transfer and low thermal efficiency of the CVD process. Here, we demonstrate a method to achieve few-layers WSe2 on an insulator via laser irradiation assisted selenization (LIAS) process directly, for which the amorphous WO3 film undergoes a reduction process in the presence of selenium gaseous vapors to form WSe2, utilizing laser annealing as a heating source. Detailed growth parameters such as laser power and laser irradiation time were investigated. In addition, microstructures, optical and electrical properties were investigated. Furthermore, a patternable WSe2 concept was demonstrated by patterning the WO3 film followed by the laser irradiation. By combining the patternable process, the transfer-free WSe2 back gate field effect transistor (FET) devices are realized on 300 nm-thick SiO2/P(+)Si substrate with extracted field effect mobility of ∼0.2 cm(2) V(-1) s(-1). Similarly, the reduction process by the laser irradiation can be also applied for the synthesis of other TMDs such as MoSe2 from other metal oxides such as MO3 film, suggesting that the process can be further extended to other TMDs. The method ensures one-step process to fabricate patternable TMDs, highlighting the uniqueness of the laser irradiation for the synthesis of different TMDs.

19.
Small ; 11(25): 3017-27, 2015 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-25808659

RESUMO

Despite the vast progress in chemical vapor deposition (CVD) graphene grown on metals, the transfer process is still a major bottleneck, being not devoid of wrinkles and polymer residues. In this paper, a structure is introduced to directly synthesize few layer graphene on insulating substrates by a laser irradiation heating process. The segregation of graphene layers can be manipulated by tuning the metal layer thickness and laser power at different scanning rates. Graphene deposition and submicrometer patterning resolution can be achieved by patterning the intermediate metal layer using standard lithography methods in order to overcome the scalability issue regardless the resolution of the laser beam. The systematic analysis of the process based on the formation of carbon microchannels by the laser irradiation process can be extended to several materials, thicknesses, and methods. Furthermore, hole and electron mobilities of 500 and 950 cm(2) V(-1) s(-1) are measured. The laser-synthesized graphene is a step forward along the direct synthesis route for graphene on insulators that meets the criteria for photonics and electronics.

20.
ACS Nano ; 9(2): 2071-9, 2015 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-25598307

RESUMO

Two-dimensional layered semiconductors present a promising material platform for band-to-band-tunneling devices given their homogeneous band edge steepness due to their atomically flat thickness. Here, we experimentally demonstrate interlayer band-to-band tunneling in vertical MoS2/WSe2 van der Waals (vdW) heterostructures using a dual-gate device architecture. The electric potential and carrier concentration of MoS2 and WSe2 layers are independently controlled by the two symmetric gates. The same device can be gate modulated to behave as either an Esaki diode with negative differential resistance, a backward diode with large reverse bias tunneling current, or a forward rectifying diode with low reverse bias current. Notably, a high gate coupling efficiency of ∼80% is obtained for tuning the interlayer band alignments, arising from weak electrostatic screening by the atomically thin layers. This work presents an advance in the fundamental understanding of the interlayer coupling and electron tunneling in semiconductor vdW heterostructures with important implications toward the design of atomically thin tunnel transistors.

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