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1.
Micromachines (Basel) ; 11(2)2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32019256

RESUMO

Stannous oxide (SnO) nanowires were synthesized by a template and catalyst-free thermal oxidation process. After annealing a Sn nanowires-embedded anodic aluminum oxide (AAO) template in air, we obtained a large amount of SnO nanowires. SnO nanowires were first prepared by electrochemical deposition and an oxidization method based on an AAO template. The preparation of SnO nanowires used aluminum sheet (purity 99.999%) and then a two-step anodization procedure to obtain a raw alumina mold. Finally, transparent alumina molds (AAO template) were obtained by reaming, soaking with phosphoric acid for 20 min, and a stripping process. We got a pore size of < 20 nm on the transparent alumina mold. In order to meet electroplating needs, we produced a platinum film on the bottom surface of the AAO template by using a sputtering method as the electrode of electroplating deposition. The structure was characterized by X-ray diffraction (XRD). High resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) with X-ray energy dispersive spectrometer (EDS) were used to observe the morphology. The EDS spectrum showed that components of the materials were Sn and O. FE-SEM results showed the synthesized SnO nanowires have an approximate length of ~10-20 µm with a highly aspect ratio of > 500. SnO nanowires with a Sn/O atomic ratio of ~1:1 were observed from EDS. The crystal structure of SnO nanowires showed that all the peaks within the spectrum lead to SnO with a tetragonal structure. This study may lead to the use of the 1D structure nanowires into electronic nanodevices and/or sensors, thus leading to nano-based functional structures.

2.
ACS Omega ; 5(1): 113-121, 2020 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-31956758

RESUMO

We report the synthesis and photovoltaic performance of a new nonstoichiometric ternary metal sulfide alloyed semiconductor-Cd x Sb2-y S3-δ nanocrystals prepared by the two-stage sequential ionic layer adsorption reaction technique. The synthesized Cd x Sb2-y S3-δ nanocrystals retain the orthorhombic structure of the host Sb2S3 with Cd substituting a fraction (x = 0-0.15) of the cationic element Sb. The Cd x Sb2-y S3-δ lattice expands relative to the host, Sb2S3, with its lattice constant a increasing linearly with Cd content x. Optical and external quantum efficiency (EQE) spectra revealed that the bandgap E g of Cd x Sb2-y S3-δ decreased from 1.99 to 1.69 eV (i.e., 625-737 nm) as x increased from 0 to 0.15. Liquid-junction Cd x Sb2-y S3-δ quantum dot-sensitized solar cells were fabricated using the polyiodide electrolyte. The best cell yielded a power conversion efficiency (PCE) of 3.72% with the photovoltaic parameters of J sc = 15.97 mA/cm2, V oc = 0.50 V, and FF = 46.6% under 1 sun. The PCE further increased to 4.86%, a respectable value for a new solar material, under a reduced light intensity of 10% sun. The PCE (4.86%) and J sc (15.97 mA/cm2) are significantly larger than that (PCE = 1.8%, J sc = 8.55 mA/cm2) of the Sb2S3 host. Electrochemical impedance spectroscopy showed that the ZnSe passivation coating increased the electron lifetime by three times. The EQE spectrum of Cd x Sb2-y S3-δ has a maximal EQE of 82% at λ = 350 nm and covers the spectral range of 300-750 nm, which is significantly broader than that (300-625 nm) of the Sb2S3 host. The EQE-integrated current density yields a J ph of 11.76 mA/cm2. The tunable bandgap and a respectable PCE near 5% suggest that Cd x Sb2-y S3-δ could be a potential candidate for a solar material.

3.
J Am Chem Soc ; 140(51): 18058-18065, 2018 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-30516996

RESUMO

Dielectric screening plays an important role in reducing the strength of carrier scattering and trapping by point defects for many semiconductors such as the halide perovskite solar materials. However, it was rarely considered as a screen to find new electronic semiconductors. We performed a material search study using the dielectric properties as a screen to identify potential electronic materials in the class of metal-pnictide ternary sulfosalts, containing Bi or Sb. These salts are basically ionic due to the electronegativity difference between the S and both the metal and pnictogen elements. However, we do find significant cross-gap hybridization between the S p-derived valence bands and pnictogen p-derived conduction bands in many of the materials. This leads to enhanced Born effective charges and, in several cases, highly enhanced dielectric constants. We find a chemical rule for high dielectric constants in terms of the bond connectivity of the pnictogen-chalcogen part of the crystal structure. We additionally find a series of compounds with low effective mass, high dielectric constant, and other properties that suggest good performance as electronic materials and also several potential thermoelectric compounds. Experimental optical data and solar conversion efficiency are reported for Sn-Sb-S samples, and results in accord with predicted good performance are found. The results illustrate the utility of dielectric properties as a screen for identifying complex semiconductors.

4.
Nanoscale Res Lett ; 13(1): 109, 2018 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-29675727

RESUMO

In this study, alpha nickel sulfide (α-NiS) nanosphere films have been successfully synthesized by electroplating the nickel nanosheet film on the indium tin oxide (ITO) glass substrate and sulfuring nickel-coated ITO glass substrate. First, we electrodeposited the nickel nanosheet films on the ITO glass substrates which were cut into a 0.5 × 1 cm2 size. Second, the nanosheet nickel films were annealed in vacuum-sealed glass ampoules with sulfur sheets at different annealing temperatures (300, 400, and 500 °C) for 4 h in vacuum-sealed glass ampoules. The α-NiS films were investigated by using X-ray diffraction (XRD), variable vacuum scanning electron microscopy (VVSEM), field emission scanning electron microscopy/energy dispersive spectrometer (FE-SEM/EDS), cyclic voltammogram (CV), electrochemical impedance spectroscopy (EIS), ultraviolet/visible/near-infrared (UV/Visible/NIR) spectra, and photoluminescence (PL) spectra. Many nanospheres were observed on the surface of the α-NiS films at the annealing temperature 400 °C for 4 h. We also used the high-resolution transmission electron microscopy (HR-TEM) for the analysis of the α-NiS nanospheres. We demonstrated that our α-NiS nanosphere film had a linear current response to different glucose concentrations. Additionally, our α-NiS nanosphere films were preserved at room temperature for five and a half years and were still useful for detecting glucose at low concentration.

5.
J Colloid Interface Sci ; 488: 246-250, 2017 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-27835818

RESUMO

We present a new ternary semiconductor absorber material - Pb1-xSnxS - for solar cells. Pb1-xSnxS nanocrystals (NCs) were synthesized using the successive ionic layer adsorption reaction (SILAR) process. Energy-dispersive X-ray spectroscopy revealed the Sn ratio for a sample prepared with five SILAR cycles to be x=0.55 (i.e. non-stoichiometric formula Pb0.45Sn0.55S). The optical spectra revealed that the energy gap Eg of the Pb1-xSnxS NCs decreased with an increasing number of SILAR cycles n, with Eg=1.67eV for the sample with n=5. Liquid-junction Pb1-xSnxS quantum dot-sensitized solar cells were fabricated using the polysulfide electrolyte. The best cell yielded a short-circuit current density Jsc of 10.1mA/cm2, an open circuit voltage of 0.43V, a fill factor FF of 50% and an efficiency of 2.17% under 1 sun. The external quantum efficiency spectrum (EQE) covered a spectral range of 300-800nm with a maximum EQE of ∼67% at λ=650nm. At the reduced light of 0.1 sun, the efficiency increased to 3.31% (with a normalized Jsc=17.7mA/cm2) - a respectable efficiency for a new sensitizer. This work demonstrates that Pb1-xSnxS shows potential as a solar cell absorber.

6.
J Colloid Interface Sci ; 473: 60-5, 2016 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-27054767

RESUMO

This work investigates the synthesis and application in solar cells of a novel solar absorber material CuBiS2. Ternary copper chalcogenide CuBiS2 nanoparticles were grown on a mesoporous TiO2 electrode by the chemical bath deposition (CBD) method. The synthesized CuBiS2 nanoparticles, size 5-10nm, have an energy gap Eg of 2.1eV. Liquid-junction quantum dot-sensitized solar cells were fabricated from the CuBiS2-sensitized electrode using a polysulfide electrolyte. Three types of counter electrodes (CEs) - Pt, Au and Cu2S - were tested. The photovoltaic performance depends on the CBD reaction time and the CE. The best cell, obtained with the Cu2S CE, exhibited the photovoltaic performance of a short-circuit current density Jsc of 6.87mA/cm(2), an open-circuit voltage Voc of 0.25V, a fill factor FF of 36% and a power conversion efficiency η of 0.62%. The present work demonstrates the feasibility of CuBiS2 as a solar energy material.

7.
Photochem Photobiol ; 84(6): 1493-9, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18513231

RESUMO

In this study a TiO2/CNT coaxial structure and standing CNT array laminated photocatalyst to enhance the photolysis efficiency of TiO2 is presented. An electrochemical bath that used a nanoporous anodic aluminum oxide membrane as the separation grating to separate two vessels with a transmembrane concentration gradient was constructed. The catalyzed photolysis efficiency was measured in terms of the photolysis-induced ion current. The experimental results demonstrate that the photolysis efficiency of TiO2 could be increased by the high electron conductibility of the standing CNT array. The experimental results also indicate that photolysis efficiency could be enhanced by increasing the height of the standing CNT array substrate; however, it degraded as the thickness of the TiO2/CNT coaxial structure and the TiO2 shell increased.


Assuntos
Nanotubos de Carbono/química , Fotólise , Titânio/química , Catálise , Elétrons , Microscopia Eletrônica de Varredura , Nanotubos de Carbono/ultraestrutura , Espectrofotometria , Análise Espectral Raman
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