Graphene-mediated band gap engineering of WO3 nanoparticle and a relook at Tauc equation for band gap evaluation

Baishya, Kaushik; Ray, Joydwip S.; Dutta, Pankaj; Das, Partha Pratim; Das, Shyamal

doi:10.1007/s00339-018-2097-0

Cited by 67 publications

(18 citation statements)

References 55 publications

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“…The energy band gap (Eg) for each sample was determined via the intercept of the linear portion of each curve with the hν axis. The obtained values for the energy gap compared with the different amount of GO are listed in Table (1). It is worth noting that a decrease in the optical energy gap with an increasing weight percentage of GO in the sample can be seen, which can be resulting from an increase in the available energy localized levels near the band edges.…”

Section: Resultsmentioning

confidence: 95%

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Enhance The Gas-Sensing Performances Of Graphene Oxide (GO) Thin Films For Detecting Nitrogen Dioxide Gas

Al-Jawdah

Jarrah²,

Al-Khaykanee³

et al. 2021

Al-Qadisiyah Journal of Pure Science

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In this work, graphene oxide (GO) synthesized via a modified Hummer method was utilized to manufacture thin films for gas sensor applications. The films were prepared on glass substrates using the spin coating technique, the concentration of GO was varied in the precursor liquid. The crystall ographic properties of the prepared GO films were analyzed using XRD and the results showed a polycrystalline structure with a crystallite size of 15.51 nm. Using the weighing method, the average film thickness was determined to be about 200 nm. UV-Vis absorption spectrometry combined with the Tauc method confirmed the indirect nature (allowed and forbidden) of electronic transitions in the samples and it also showed a decrease in the optical energy gap with an increasing amount of GO in the samples. Values for Eg ranged from 2.4 eV to 2.15 eV for allowed transitions and from 3.05 eV to 2.6 eV for forbidden transitions. Gas sensing measurements were performed using NO2 as target gas at different operating temperatures (50, 100, 200 and 300 oC), as well as four target gas concentration (100 ppm, 400 ppm, 700 ppm, and 1000 ppm) have been tested and shows the good response in the range of 10%. It can be seen that the sensitivity increases with increasing operating temperature and gas concentration. At 300 oC operating temperature response and recovery time decrease to their lowest value or 2.6 and 5 seconds, respectively.

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Section: Resultsmentioning

confidence: 95%

“…The data of absorption coefficient versus wavelength shown in (Figure 3) were used to estimate the optical energy gap (Eg) using Tauc's equation [1,13]:…”

Section: Figure 2: X -Ray Diffraction Pattern For Thin Go Films Deposited On Glassmentioning

confidence: 99%

Enhance The Gas-Sensing Performances Of Graphene Oxide (GO) Thin Films For Detecting Nitrogen Dioxide Gas

Al-Jawdah

Jarrah²,

Al-Khaykanee³

et al. 2021

Al-Qadisiyah Journal of Pure Science

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“…Believe that the Pristine-NiO NPs exposing the quite blue shift compared to co-doped NiO NPs samples imply that the quantum size confinement effect and having a larger bandgap, and after the dopant contribution, will narrow the bandgap. Above the determinations are caused due to creations of vacancies implied on host matrix and the new energy states in the Pristine-NiO, may it happen that substituted dopants species will generate charge (holes) near NiO valence band edge, probably this could decrease the bandgap energy [18,31,40,41]. Eventually, the analyzed UV-Vis absorbance results clarify the interdependency of crystallite size, impurities, oxygen deficiencies, where it is nearly having a good agreement for the XRD studies in the present work.…”

Section: Uv-vis Analysismentioning

confidence: 99%

Effect of co-dopant proportion on the structural, optical and magnetic properties of pristine NiO nanoparticles synthesized by Sol–gel method

Jothibas

Bharanidharan

Paulson

et al. 2021

J Mater Sci: Mater Electron

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In this present work, the pristine and the different percentages of co-doped NiO nanoparticles have been successfully synthesized through the sol-gel method. The X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), UV-Visible spectroscopy (UV-Vis), Fourier Transform Infra-Red Spectroscopy (FT-IR), and Vibrating Sample Magnetometer (VSM) were used to study the structural, morphological, optical, functional, and magnetic properties of the synthesized materials. The XRD patterns confirmed the formation of cubic phased NiO with their crystallite size, microstrain, dislocation density was estimated, and the average crystallite size increased with co-dopant inclusion. By introducing the co-dopant proportion in NiO lattice, the intensity of optical absorption was found to increase and the optical bandgap decreased from (E g = 3.6, 3.54, 3.50 eV) due to quantum size effect. SEM result exhibits that the particles are spherical-shaped morphology. The VSM examination shows the magnetic transition of soft to hard-ferromagnetism in room temperature on Zn, Mn codopant ions occupying Ni translational symmetry.

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“…Comparing curve (a) and curve (b) in Figure 4, it can be found that Bi 2 S 3 has absorption red shift after doping NG. Based on UV-VIS-INF-DRS spectrum, according to Tauc [22] equation, the direct band gaps of Bi 2 S 3 and NG/Bi 2 S 3 can be calculated.…”

Section: Near-infrared Diffuse Spectra Visible From the Uvmentioning

confidence: 99%

Photocatalytic degradation of ammonia-nitrogen via N-doped graphene/bismuth sulfide catalyst under near-infrared light irradiation

Liu

2021

ACE

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The N-doped graphene/bismuth sulfide (NG/Bi2S3) composite was synthesized by hydrothermal method. The structure and properties of the catalyst were characterized by X-ray powder diffraction, Raman spectroscopy, scanning electron microscopy and UV-visible near-infrared diffuse reflectance spectroscopy. The degradation of ammonia-N was studied using 0.050 g NG/Bi2S3 as photocatalyst under near-infrared light irradiation. The results show that the degradation ratio of ammonia-N reaches 91.4% in 100.0 mg·L-1 ammonia-N solution with pH 9.0 under near-infrared light irradiation for 10 h. Under similar conditions，the degradation ratio of ammonia-N is only 65.5% when pure Bi2S3 is used as the photocatalyst. Kinetic studies show that the ammonia-N degradation follows the first-order reaction kinetics, and the average value of the apparent rate constant is 0.1240 h-1. Catalyst stability studies show that the degradation ratio of ammonia nitrogen in 7 runs is still greater than 85.5%, which indicates that the NG/Bi2S3 composite catalyst is very stable.

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Graphene-mediated band gap engineering of WO3 nanoparticle and a relook at Tauc equation for band gap evaluation

Cited by 67 publications

References 55 publications

Enhance The Gas-Sensing Performances Of Graphene Oxide (GO) Thin Films For Detecting Nitrogen Dioxide Gas

Enhance The Gas-Sensing Performances Of Graphene Oxide (GO) Thin Films For Detecting Nitrogen Dioxide Gas

Effect of co-dopant proportion on the structural, optical and magnetic properties of pristine NiO nanoparticles synthesized by Sol–gel method

Photocatalytic degradation of ammonia-nitrogen via N-doped graphene/bismuth sulfide catalyst under near-infrared light irradiation

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