Photocatalytic application of Graphene oxide-ZnO nanocomposite for the reduction of methylene blue dye

Author(s):  
Bansura Banu ◽  
Mercy Jennifer ◽  
Udith Ferdila

Abstract The Graphene Oxide (GO) and GO-Zinc Oxide (GO-ZnO) nanocomposite were prepared using simplified techniques with modified Hummer’s and solvothermal methods for photocatalytic application. In a comparative study, the optimized geometries, binding energies, electronic properties, non-linear optical properties and density of states of GO-ZnO were calculated using density functional theory (DFT) calculations with B3LYP method at 6-31G (d,p) and LanL2DZ basis sets to examine the binding site of a methylene blue (MB) dye systematically. The result of Natural bond orbital (NBO) analysis revealed the effective charge transfer and also explained the mechanism and efficiency of the photocatalytic activity of GO-ZnO. Density of states supported the strong interaction of MB with the GO-ZnO leading to the degradation of the MB dye. The attained theoretical results depict the existence of n → σ*, n → n* and σ → σ* interactions, improved charge transfer, reduced band gap which establish the use of GO-ZnO in the visible light photocatalytic performance. Characterization methods such as XRD, FTIR and UV were carried out to support our theoretical results. The XRD results confirmed the particle size of 21 nm with inter layer spacing of 0.87 nm. FTIR spectroscopy indicated the characteristic bands related to the elements in GO-ZnO. The higher electrical conductivity is studied using UV-Vis spectral analysis. The calculated results show good agreements with experimental observations reveal that the GO-ZnO has good photocatalytic behavior.

2019 ◽  
Vol 26 (04) ◽  
pp. 1850170 ◽  
Author(s):  
AMIRALI ABBASI ◽  
JABER JAHANBIN SARDROODI

The gas response of metal oxide-based sensors depends strongly on its adsorption properties. To explore the potential sensing capability of pristine and nitrogen modified TiO2/graphene oxide (GO) heterostructures, the adsorption of NO2 molecule on the N-doped nanocomposites was investigated using density functional theory (DFT) calculations. Six possible configurations were simulated based on the estimated adsorption energies. The binding sites were located over the oxygen, doped nitrogen and five-fold coordinated titanium atoms of TiO2. The electronic properties including atomic Mulliken population, projected density of states and molecular orbitals were investigated in detail. The N–O bonds of the NO2 molecule were significantly increased after the adsorption process. The adsorption of NO2 molecule on the N-doped nanocomposite is more energetically favorable than the adsorption on the undoped one. The results suggest that NO2 chemisorbs on the considered nanocomposites. Mulliken population analysis reveals a noticeable charge transfer from the nanocomposite to the molecule, which indicate that NO2 acts as a charge acceptor. Molecular orbital calculations show that the highest occupied molecular orbitals (HOMOs) of the studied systems were mainly localized on the adsorbed NO2 molecule. The significant overlaps in the projected density of states (PDOS) spectra of the interacting atoms confirm the formation of chemical bonds between them. There is a direct relationship between the results of charge transfer and sensing responses. N-doped nanocomposites have better sensing response than the undoped ones. The results highlight the possibility to develop innovative highly efficient NO2 sensors based on novel TiO2/GO nanocomposites.


2019 ◽  
Vol 487 ◽  
pp. 539-549 ◽  
Author(s):  
Mohamed Mokhtar Mohamed ◽  
Mohamed A. Ghanem ◽  
Mohamed Khairy ◽  
Eman Naguib ◽  
Nouf H. Alotaibi

2016 ◽  
Vol 18 (14) ◽  
pp. 9658-9665 ◽  
Author(s):  
Rafael B. Araujo ◽  
Sudip Chakraborty ◽  
Prabeer Barpanda ◽  
Rajeev Ahuja

We have employed density functional theory to systematically investigate the crystal structure evolution, density of states and charge transfer with sodium ions insertion, and the corresponding average redox potential, for Na2M2(SO4)3 (M = Fe, Mn, Co and Ni).


2020 ◽  
Vol 309 ◽  
pp. 113171 ◽  
Author(s):  
Mehmet Harbi Calimli ◽  
Mehmet Salih Nas ◽  
Hakan Burhan ◽  
Sibel Demiroglu Mustafov ◽  
Özkan Demirbas ◽  
...  

2020 ◽  
pp. 2050048
Author(s):  
A. MOKADEM ◽  
M. BOUSLAMA ◽  
B. KHAROUBI ◽  
A. OUERDANE ◽  
R. KHENATA ◽  
...  

We investigate the growth performance of tin oxide on the Si substrate, achieved by spray pyrolysis using the sensitive analysis techniques X-Ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). These complementary techniques confirm the growth of homogeneous SnO2 thin films. We also study the electronic distribution of the valence band of SnO2 theoretically using density functional theory (DFT). The chemical and physical properties of the material depend on the electron structure varying as a function of energy. The density of states (DOS) is calculated using the modified Becke–Johnson-Generalized Gradient Approximation (mBJ-GGA) in order to identify the electronic orbitals and the importance of their contribution to the electronic structure of the valence band. Furthermore, we use the experimental technique UV Photoelectron Spectroscopy (UPS) for studying the electronic distribution within the valence band and for validating the theoretical results of the density of states of SnO2/Si.


2020 ◽  
Vol 979 ◽  
pp. 175-179
Author(s):  
M. Nagalakshmi ◽  
N. Anusuya ◽  
S. Karuppuchamy

Titanium dioxide (TiO2) nanoparticles have been successfully prepared by biological method and the resulting material was characterized by XRD, FTIR, SEM, EDAX and UV-Vis spectroscopy. The synthesized TiO2 materials successfully degraded the methylene blue dye (MB) under UV light irradiation.


2019 ◽  
Vol 04 ◽  
Author(s):  
Sachin Dev ◽  
Man Singh

Introduction: The Metal Sulfide Nanoparticles Doped Graphene Oxide Sheets Have Been Studied And Were Used To Adsorb Fluorescent Methylene Blue Dye. Such Mechanism Efficiently Reduces The Dyes And Their Fluorescent Pollutants Through The Positive And Negative Holes. The Metal Sulfide Doped Graphene Oxide Could Be A Most Potential Route To Reduce From Fluorescent To Non-Fluorescent Species To Prevent The Global Warming And Other Pollution Being Caused By Them. Objectives: This Study Has Been To Strengthen And Widen The Applications Of Negative And Positive Holes Quick Formation At A Negligible Energy Barrier. Metal Sulfide Nanoparticles Were Doped With Graphene Oxide To Further Strengthen The Semiconducting And To Fastened The Rate Of Adsorption Of Methylene Blue Dye. Methods: Graphite Flakes Were Oxidized To Graphite Oxide With High Yield. The Graphite Oxide Was Sonicated In Water To Obtain Graphene Oxide And Doped With Metal Sulfide Nanoparticles In Situ. The Samples Were Characterized With High End Instruments And Used For Adsorption. Results: The Metal Sulfide Nanoparticles Were Successfully Doped With Graphene Oxide. The Ftir And Xps Spectra Infer Doping Of Metal Sulfide Nanoparticle In Graphene Oxide. That Enhanced Methylene Blue Adsorption Upto 97%. Conclusion: The Common Adsorption Effect Of Methylene Blue With Bare Graphene Oxide And Metal Sulfide Nanoparticles Doped Graphene Oxide Were Studied In This Paper. The Methylene Blue Adsorption Was Maximum (97%) By Cadmium Sulfide Doped Graphene Oxide Compared To Bare Graphene Oxide (87%), Nickel Sulfide Doped Graphene Oxide (79%), And Zinc Sulfide Doped Graphene Oxide (89%). The Metal Sulfide Nanoparticles Have Successfully Enhanced A Semiconductor Mechanism Of Graphene Oxide Especially With 3d And 4d10 Of Cds.


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