scholarly journals Effects of In Situ Co or Ni Doping on the Photoelectrochemical Performance of Hematite Nanorod Arrays

2020 ◽  
Vol 10 (10) ◽  
pp. 3567
Author(s):  
Feng Cheng ◽  
Xiuwei Li
Keyword(s):  
Band Gap ◽  
Energy Gap ◽  
Saturated Calomel Electrode ◽  
Molar Ratio ◽  
Flat Band ◽  
Flat Band Potential ◽  
Nanorod Arrays ◽  
Ni Doping ◽  
Co Doped

Co-doped and Ni-doped hematite (α-Fe2O3) nanorod arrays were prepared on fluorine-doped tin oxide (FTO) conductive glass via aqueous chemical growth, in which the doping and the formation of nanorods occurred simultaneously (i.e., in situ doping). These samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet (UV)–visible spectrophotometry, linear sweep voltammetry and Mott–Schottky (M–S) measurement. Results showed that the introduction of 5% Co or Ni into α-Fe2O3 (the molar ratio of dopant to Fe is 1:20) did not change its crystal phase, morphology, energy gap and flat band potential. Both the undoped and the doped α-Fe2O3 showed a direct band gap of 2.24 eV, an indirect band gap of 1.85 eV, and a flat band potential of −0.22 V vs. saturated calomel electrode (SCE). At an applied potential of 0.2 V vs. SCE, the Co-doped and the Ni-doped α-Fe2O3 exhibited a photocurrent of 1.28 mA/cm2 and 0.79 mA/cm2, respectively, which were 2.1 times and 1.3 times that of the undoped α-Fe2O3. After the Co or Ni doping, the charge carrier concentration increased from 1.65 × 1025 m−3 to 3.74 × 1025 m−3 and 2.50 × 1025 m−3, respectively. Therefore, the increase in the photocurrent of the doped α-Fe2O3 was likely attributed to their enhanced conductivity.

scholarly journals In situ synthesis of ordered mesoporous Co-doped TiO2 and its enhanced photocatalytic activity and selectivity for the reduction of CO2

2015 ◽  
Vol 3 (18) ◽  
pp. 9491-9501 ◽  
Author(s):  
Tao Wang ◽  
Xianguang Meng ◽  
Guigao Liu ◽  
Kun Chang ◽  
Peng Li ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Energy Band ◽  
In Situ Synthesis ◽  
Molar Ratio ◽  
Doped Tio2 ◽  
Ordered Mesoporous ◽  
Reduction Of Co2 ◽  
Co Doped

The photocatalytic selectivity is improved by optimizing the energy-band configurations of Co-doped TiO2 through varying the molar ratio of Co/Ti.

Effects of Al on the Flat Band Potential of Nanostructured TiO2 Electrodes

2013 ◽  
Vol 291-294 ◽  
pp. 2731-2733
Author(s):  
Shu Ming Yang ◽  
Guang Hui Zhu ◽  
Shu Pei Guo
Keyword(s):  
Energy Gap ◽  
Visible Region ◽  
Raw Material ◽  
Flat Band ◽  
Flat Band Potential ◽  
X Ray Diffraction ◽  
Visible Spectroscopy ◽  
Al Doping ◽  
Doped Tio2 ◽  
X Ray

In this paper, Al(NO3)3•9H2O was used as raw material and the nanoparticles of Al-doped TiO2 were prepared by hydrothermal method. The nanoparticles and films were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Ultraviolet and Visible Spectroscopy (UV-Vis). The flat band potential (Efb) of nanostructured TiO2 and Al-doped TiO2 in acetone have been determined with spectroelectrochemistry measurement. The results show that Al doping decreases the energy gap and improves the absorption ability in visible region. On the other hand, Al doping TiO2 can effectively embarrass the crystal growth of TiO2. Specifically, the Efb of TiO2 and Al-doped TiO2 can be determined to be -0.6 V and -0.3V.

scholarly journals Synthesis and Characterization of TNTs/Polyaniline Composite as Photocatalyst Degradation of Rhodamin B by Visible Light

2017 ◽  
Vol 3 (5) ◽  
pp. 41
Author(s):  
Atik Setyani ◽  
Sri Wahyuni ◽  
Sigit Priatmoko ◽  
Emas Agus Prastyo Wibowo ◽  
Nur Amin
Keyword(s):  
Energy Gap ◽  
In Situ Polymerization ◽  
Anatase Phase ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Molar Ratio ◽  
Pani Composite ◽  
Stretching Vibration

<p>The purpose of this research is to study the effect of the amount of aniline on their photocatalytic activity. Nano TiO<sub>2</sub> was synthesized using sol-gel method with TiPP precursor. XRD characterization results showed that nano TiO<sub>2</sub> with calcination temperature of 450 °C had size of 13.8 nm with high crystalline. The diffraction peaks of nano TiO<sub>2</sub> at 2θ are 24.45°; 37.075°; 47.26° and 53.18°. Nano TiO<sub>2</sub> was then synthesized with hydrothermal treatment 24 h of 140 °C to produce TNTs. The results of XRD analysis shows anatase phase with field (004) and (200). The morphology of TNTs begins to form at the calcinations temperature of 600 °C with textural coefficient value of 0.998 3 . Synthesis of composite TNTs/PANI (polyaniline) was done by in situ polymerization technique of aniline which was already contained nano TiO<sub>2</sub>. The molar ratio of aniline and APS in the synthesis of a composite is 1:1.5 with the addition of aniline of 15 %; 20 % and 25 % (w/w %). Characterization using FTIR showed the stretching vibration of the C=N in wavelength of 1 600 cm<sup>–1</sup> to mark the formation of quinonoid compounds of polyaniline. The test of the rhodamine B degradation gave the best results on the 25 % TNTs/PANI composite, with the degradation percentage of 58.73 %. The characterization results using dr-uv proved that the decrease of energy gap in the TNTs/PANI composite which as evidenced with Kubelka-Munk calculation equation that was 25 % TNTs/PANI amounting to 3.19 eV and TNTs at 3.24 eV.</p>

scholarly journals Synthesis of four-angle star-like CoAl-MMO/BiVO4 p–n heterojunction and its application in photocatalytic desulfurization

RSC Advances ◽  
2017 ◽  
Vol 7 (41) ◽  
pp. 25455-25460 ◽  
Author(s):  
Limin Yun ◽  
Zhanxu Yang ◽  
Zong-Bao Yu ◽  
Tianfeng Cai ◽  
Yue Li ◽  
...  
Keyword(s):  
Visible Light ◽  
Band Gap ◽  
Visible Light Irradiation ◽  
Photocatalytic Oxidation ◽  
Light Irradiation ◽  
Flat Band ◽  
Flat Band Potential ◽  
Highly Efficient ◽  
Highly Dispersed

Four-angle star-like BiVO4 loaded with highly dispersed CoAl-MMO nanoparticles demonstrated highly efficient photocatalytic oxidation of thiophene under visible light irradiation. It's due to a narrower band gap, and more negative flat band potential of the composite.

Chemical binding of pyridine on TiO2 nanocrystalline film and its photoelectrochemical properties

2010 ◽  
Vol 25 (1) ◽  
pp. 32-38 ◽  
Author(s):  
Kangsheng Huang ◽  
Jianguang Jia ◽  
Xiaowen Zhou ◽  
Yuan Lin ◽  
Xurui Xiao
Keyword(s):  
Thermal Activation ◽  
Flat Band ◽  
Flat Band Potential ◽  
Photoelectrochemical Properties ◽  
Nanocrystalline Film ◽  
Nanocrystalline Films ◽  
Step Method ◽  
Chemical Binding ◽  
Surface Dipole

Aiming to bind molecules without O-containing groups such as the –OH or –COOH functional groups, a new two-step method involving thermal activation and followed by an in situ chemical reaction was suggested, and the binding of the pyridine molecule on TiO2 nanocrystalline films was realized. UV-Vis, FTIR, and XPS characterizations revealed that pyridine molecules are chemically linked to the TiO2 surface by forming Ti-pyridine bonds. Mott-Schottky measurements indicated that the binding of pyridine results in a positive shift of the flat band potential for TiO2 nanocrystalline film, which is attributed to the alternating surface dipole moment of TiO2 nanocrystals upon pyridine binding. Electrochemical and photoelectrochemical investigations indicated that the binding of pyridine on TiO2 nanocrystalline film has high electrochemical and photoelectrochemical stability.

scholarly journals Structural and Photoluminescence Investigations of Tb3+/Eu3+ Co-Doped Silicate Sol-Gel Glass-Ceramics Containing CaF2 Nanocrystals

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 754
Author(s):  
Natalia Pawlik ◽  
Barbara Szpikowska-Sroka ◽  
Tomasz Goryczka ◽  
Joanna Pisarska ◽  
Wojciech A. Pisarski
Keyword(s):  
Sol Gel ◽  
Glass Ceramics ◽  
Emission Spectra ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Co Doping ◽  
Near Ultraviolet ◽  
Transmission Electron ◽  
Co Doped

In this work, the series of Tb3+/Eu3+ co-doped xerogels and derivative glass-ceramics containing CaF2 nanocrystals were prepared and characterized. The in situ formation of fluoride crystals was verified by an X-ray diffraction technique (XRD) and transmission electron microscopy (TEM). The studies of the Tb3+/Eu3+ energy transfer (ET) process were performed based on excitation and emission spectra along with luminescence decay analysis. According to emission spectra recorded under near-ultraviolet (NUV) excitation (351 nm, 7F6 → 5L9 transition of Tb3+), the mutual coexistence of the 5D4 → 7FJ (J = 6–3) (Tb3+) and the 5D0 → 7FJ (J = 0–4) (Eu3+) luminescence bands was clearly observed. The co-doping also resulted in gradual shortening of a lifetime from the 5D4 state of Tb3+ ions, and the ET efficiencies were varied from ηET = 11.9% (Tb3+:Eu3+ = 1:0.5) to ηET = 22.9% (Tb3+:Eu3+ = 1:2) for xerogels, and from ηET = 25.7% (Tb3+:Eu3+ = 1:0.5) up to ηET = 67.4% (Tb3+:Eu3+ = 1:2) for glass-ceramics. Performed decay analysis from the 5D0 (Eu3+) and the 5D4 (Tb3+) state revealed a correlation with the change in Tb3+–Eu3+ and Eu3+–Eu3+ interionic distances resulting from both the variable Tb3+:Eu3+ molar ratio and their partial segregation in CaF2 nanophase.

In Situ Monitoring of Anodic Oxide Growth on SI (001) by Interface Second-Harmonic Generation

1997 ◽  
Vol 502 ◽  
Author(s):  
S. Janz ◽  
J. A. Bardwell
Keyword(s):  
Space Charge ◽  
Nonlinear Optical ◽  
Second Harmonic ◽  
Anodic Oxide ◽  
In Situ Monitoring ◽  
Flat Band ◽  
Oxide Growth ◽  
Flat Band Potential ◽  
Oxide Interface

ABSTRACTOptical second-harmonic (SH) generation is used to monitor the anodic growth of oxide on a (001) Si surface. The measured SH intensity is dominated by the nonlinear optical response of the space charge region in the Si just below the Si/oxide interface. The interface SH technique can detect the onset of H desorption, identify the flat band potential, and probe the evolution of space charge within the growing oxide layer.

scholarly journals Optical and Thermal Properties of Zn/Al-Layered Double Hydroxide Nanocomposite Intercalated with Sodium Dodecyl Sulfate

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Samaneh Babakhani ◽  
Zainal Abidin Talib ◽  
Mohd Zobir Hussein ◽  
Abdullah Ahmed Ali Ahmed
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Band Gap ◽  
Optical Band Gap ◽  
Energy Gap ◽  
Sodium Dodecyl ◽  
Sulfate Solution ◽  
Molar Ratio ◽  
Basal Spacing ◽  
Dodecyl Sulfate ◽  
Double Hydroxide

Zn/Al-LDH-SDS nanocomposites have been prepared using a coprecipitation method in different molar ratio of Zn2+/Al3+= 2, 3, and 4 at pH = 10 and different concentrations of sodium dodecyl sulfate solution (0.2 M, 0.4 M, and 0.8 M). The XRD and FTIR data show the successful intercalation of SDS into the LDH interlayer. The XRD diffractogram showed that the basal spacing forZn/Al–NO3-is 0.89 nm compared to 2.54–2.61 nm for the Zn/Al-SDS nanocomposite. Optical band gap of the samples was calculated using Kubelka-Munk model. Due to the presence of LDH phase, two band gap energies (Eg1andEg2) were observed. The values ofEg1andEg2were found around 4.8 eV and 3.75 eV for Zn/Al-LDH (r= 2, 3, and 4). The values of band gap of LDH-SDS nanocomposites were found to increase to around 4.2 eV and 5.2 eV. For Zn4Al-LDH-SDS with 0.4 M and 0.8 M of SDS, only one energy gap at around 3.23 eV was observed. The optical band gap ofSO42-phase increased as the amount of SDS increases. Thermal diffusivity of the resulted nanocomposite was also investigated.

Photoelectrochemical Characteristics of n-InSe Single Crystals

1995 ◽  
Vol 60 (12) ◽  
pp. 2039-2046
Author(s):  
Ioannis Poulios ◽  
Kostantinos Farmakis ◽  
Kostantinos Paraskevopoulos
Keyword(s):  
Aqueous Solutions ◽  
Single Crystals ◽  
Energy Gap ◽  
Flat Band ◽  
Flat Band Potential ◽  
Differential Capacity ◽  
Redox Systems ◽  
Donor Density ◽  
Presence And Absence

The photoelectrochemical behaviour of n-InSe single crystals in aqueous solutions has been studied in the presence and absence of several redox systems. Among them, Ce3+/4+ and KI/I2 yielded the highest photocurrents, photovoltages and show the highest stability. The semiconductor energy gap Eg = 1.2 eV, has been calculated from transmittance measurements. The flat band potential UFB = -0.40 V vs NHE and the donor density have been calculated from differential capacity measurements.

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