scholarly journals Surface photosensitization of ZnO by ZnS to enhance the photodegradation efficiency for organic pollutants

2021 ◽  
Vol 3 (7) ◽  
Author(s):  
Sunaina ◽  
Sapna Devi ◽  
S. T. Nishanthi ◽  
S. K. Mehta ◽  
A. K. Ganguli ◽  
...  
Keyword(s):  
Methyl Orange ◽  
Organic Dyes ◽  
Light Exposure ◽  
Low Cost ◽  
Visible Region ◽  
Zns Nanoparticles ◽  
Electron Hole ◽  
Photodegradation Efficiency ◽  
Electron Hole Pair ◽  
Scalable Synthesis

AbstractIt is challenging to develop a material which has low cost, high activity, good stability and recyclability under light exposure. Apart from these properties, the photocatalyst should also have good visible region absorbance and low electron-hole pair recombination rate. Keeping all this in view, we have designed a simple scalable synthesis of ZnO–ZnS heterostructures for the photocatalytic treatment of industrial waste (p-nitrophenol and methyl orange). The ZnO–ZnS heterostructures are synthesized via a solvent-free route by thermal annealing of solid-state mixture of ZnO and thiourea (a sulphur source) which results in ZnO–ZnS core shell kind of heterostructure formation. The interface formation between the ZnO–ZnS heterostructure favored the band-gap reduction in comparison to the bare ZnO and ZnS nanoparticles. Further, these ZnO–ZnS heterostructures were utilized as a photocatalyst for the degradation of toxic phenolic molecules (p-nitrophenol) and harmful organic dyes (methyl orange) present in the water under the light exposure (> 390 nm).

Ti3C2-MXene/Bismuth Ferrite Nanohybrids for Efficient Degradation of Organic Dye and Colorless Pollutant

2019 ◽  
Author(s):  
Ayesha Tariq ◽  
M. Abdullah Iqbal ◽  
S. Irfan Ali ◽  
Muhammad Z. Iqbal ◽  
Deji Akinwande ◽  
...  
Keyword(s):  
Surface Area ◽  
Low Cost ◽  
Bismuth Ferrite ◽  
Organic Dye ◽  
Two Dimensional ◽  
Electron Hole ◽  
Photocatalytic Application ◽  
Electron Hole Pair ◽  
Pair Generation ◽  
Photocatalytic Applications

<p>Nanohybrids, made up of Bismuth ferrites/Carbon allotropes, are extensively used in photocatalytic applications nowadays. Our work proposes a nanohybrid system composed of Bismuth ferrite nanoparticles with two-dimensional (2D) MXene sheets namely, the BiFeO<sub>3</sub> (BFO)/Ti<sub>3</sub>C<sub>2</sub> (MXene) nanohybrid for enhanced photocatalytic activity. We have fabricated the BFO/MXene nanohybrid using simple and low cost double solvent solvothermal method. The SEM and TEM images show that the BFO nanoparticles were attached onto the MXene surface and in the inter-layers of two-dimensional (2D) MXene sheets. The photocatalytic application is tested for the visible light irradiation which showed the highest efficiency among all pure-BFO based photocatalysts, i.e. 100% degradation in 42 min for organic dye (Congo Red) and colorless aqueous pollutant (acetophenone) in 150 min, respectively. The present BFO-based hybrid system exhibited the large surface area of 147 m<sup>2</sup>g<sup>-1</sup>measured via Brunauer-Emmett-Teller (BET) sorption-desorption technique, and is found to be largest among BFO and its derivatives. Also, the photoluminescence (PL) spectra indicate large electron-hole pair generation. Fast and efficient degradation of organic molecules is supported by both factors; larger surface area and lower electron-hole recombination rate. The BFO/MXene nanohybrid presented here is a highly efficient photocatalyst compared to other nanostructures based on pure BiFeO<sub>3</sub> which makes it a promising candidate for many future applications.</p>

scholarly journals Bioremediation of organic dyes using combination of plants ash

2019 ◽  
Vol 7 (2) ◽  
pp. 240-246
Author(s):  
Kaur Harpreet ◽  
Kaur Harpreet ◽  
Vandana Kamboj ◽  
Vandana Kamboj
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Methyl Orange ◽  
Crystal Violet ◽  
Congo Red ◽  
Organic Dyes ◽  
Low Cost ◽  
Sem Image ◽  
Orange Peels

Water is the most crucial thing to mankind and so its contamination by various agencies is posing a threat to the natural balance. So, in the present work, the efficiency of various adsorbents derived from plant waste, to remove different dyes from aqueous solution was evaluated. Parameters for study were contact time, concentration and pH. Various combinations of plant ashes were used for the study. It was found that adsorbent prepared from the combination of orange peels, pomegranate and banana peels ashes, exhibited good adsorption capacity for methylene blue, congo red and crystal violet. All these dyes were completely removed from the aqueous solution while methyl orange was not removed. Congo red was removed completely within 40 min of contact with the adsorbent while methyl orange took 3 hrs to be removed to the extent of 48% only. The adsorption coefficient of congo red was found to be 2.33 while value for methylene blue and crystal violet was 1 and 1.66 respectively. The characterization of adsorbent was done by Scanning Electron Microscopy and IR spectroscopy. SEM image revealed the surface of adsorbent to be made of differential pores. From the results it became evident that the low-cost adsorbent could be used as a replacement for costly traditional methods of removing colorants from water.

scholarly journals Mechanistic Insights into Photodegradation of Organic Dyes Using Heterostructure Photocatalysts

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 430 ◽  
Author(s):  
Yi-Hsuan Chiu ◽  
Tso-Fu Chang ◽  
Chun-Yi Chen ◽  
Masato Sone ◽  
Yung-Jung Hsu
Keyword(s):  
Charge Carrier ◽  
Organic Dyes ◽  
Low Cost ◽  
Reaction Medium ◽  
Degradation Process ◽  
Active Species ◽  
Solution Temperature ◽  
Dye Molecules ◽  
Operational Parameters ◽  
Photodegradation Efficiency

Due to its low cost, environmentally friendly process, and lack of secondary contamination, the photodegradation of dyes is regarded as a promising technology for industrial wastewater treatment. This technology demonstrates the light-enhanced generation of charge carriers and reactive radicals that non-selectively degrade various organic dyes into water, CO2, and other organic compounds via direct photodegradation or a sensitization-mediated degradation process. The overall efficiency of the photocatalysis system is closely dependent upon operational parameters that govern the adsorption and photodegradation of dye molecules, including the initial dye concentration, pH of the solution, temperature of the reaction medium, and light intensity. Additionally, the charge-carrier properties of the photocatalyst strongly affect the generation of reactive species in the heterogeneous photodegradation and thereby dictate the photodegradation efficiency. Herein, this comprehensive review discusses the pseudo kinetics and mechanisms of the photodegradation reactions. The operational factors affecting the photodegradation of either cationic or anionic dye molecules, as well as the charge-carrier properties of the photocatalyst, are also fully explored. By further analyzing past works to clarify key active species for photodegradation reactions and optimal conditions, this review provides helpful guidelines that can be applied to foster the development of efficient photodegradation systems.

Carbon-Based Solar Cell from Amorphous Carbon with Nitrogen Incorporation

2012 ◽  
Vol 576 ◽  
pp. 785-788 ◽  
Author(s):  
A.N. Fadzilah ◽  
K. Dayana ◽  
Mohamad Rusop
Keyword(s):  
Solar Cell ◽  
Amorphous Carbon ◽  
Temperature Increase ◽  
Low Cost ◽  
Chemical Vapor ◽  
Device Structure ◽  
Electron Hole ◽  
Nitrogen Doped ◽  
Current Voltage ◽  
Electron Hole Pair

Nitrogen doped amorphous carbon (n-C:N) solar cells were successfully prepared using a simple and low cost Chemical Vapor Deposition (CVD) method using camphor oil as a precursor. Four samples of n-C:N were deposited by varying the deposition temperature (500oC, 550oC, 600oC, 650oC). The fabricated solar cell using n-C:N with the configuration of Au/n-C:N/p-Si/Au achieved an increasing efficiency as temperature increase (0.000202% to 0.001089%). As a reference, pure a-C was deposited at 500oC and exhibit 0.000048% efficiency. The current-voltage (I-V) graph emphasized on the linear graph (ohmic) for the a-C thin films, whereas for the p-n device structure, a rectifying curve was obtained. Electrical conductitivity possesses increasing value (1.69 x 10-2 to 22 Ω-1 cm-1) due to increasing sp2 ratio in a-C as temperature increase. The rectifying curves signify the heterojunction between the n-doped a-C film and the p-Si substrate and designate the generation of electron-hole pair of the samples under illumination. Photoresponse characteristics of the deposited a-C was highlighted when being illuminated (AM 1.5 illumination: 100 mW/cm2, 25oC) and optical band gap for the nitrogen doped a-C is reported from 0.75 eV to 0.25 eV as temperature increase.

scholarly journals Bandgap Engineering and Plasmonically Enhanced Sun Light Photocatalyis in Au/Cd1-xZnxS Nanocomposites

2021 ◽  
Author(s):  
Pavan Prasad Gotipamul ◽  
Karthik Dilly Rajan ◽  
Shweta Khanna ◽  
Maheswaran Rathinam ◽  
Chidambaram Siva
Keyword(s):  
Dye Degradation ◽  
Light Exposure ◽  
Average Particle Size ◽  
Visible Region ◽  
Average Particle ◽  
Bandgap Engineering ◽  
Electron Microscopic ◽  
Photocatalytic Effect ◽  
Electron Hole Pair ◽  
Xrd Patterns

Abstract Metal nanoparticles incorporated semiconductor nanomaterials generally holds a series of advantages especially enhanced electron-hole pair lifetime and thus exhibits superior solar energy conversions. In this study, we report a facile solution processing of Au incorporated Cd1-xZnxS, where x = 0, 0.25, 0.5, 0.75 & 1, nanocomposites and their enhanced photocatalytic applications. The Au/CdZnS nanocomposites were investigated for their structural, morphological, optical and photocatalytic properties. The XRD patterns indicated the crystalline sizes of CdZnS are found to fall with the range of 1-3 nm. The electron microscopic images publicized the average particle size of Cd0.25Zn0.75S is 4 nm. The bandgap values of pristine CdS, pristine ZnS, Cd0.75Zn0.25S, Cd0.5Zn0.5S and Cd0.25Zn0.75S are 2.21 eV, 3.4 eV, 2.29 eV, 2.31 eV and 2.53 eV, respectively. The optical band gap of the CdZnS nanomaterials have got reduced for Au incorporation due to the occurrence of red shift and the enhanced visible region absorption for the inclusion of Au. The visible light photocatalytic effect of the nanocomposites have been evaluated with methylene blue (MB) dye degradation reaction under sunlight light exposure. The Au incorporated Cd0.25Zn0.75S nanocompound had exhibited 97 % of photocatalytic degradation of MB dye molecules which is 20% higher than the bare Cd0.25Zn0.75S nanocompound.

Ti3C2-MXene/Bismuth Ferrite Nanohybrids for Efficient Degradation of Organic Dye and Colorless Pollutant

2019 ◽  
Author(s):  
Ayesha Tariq ◽  
M. Abdullah Iqbal ◽  
S. Irfan Ali ◽  
Muhammad Z. Iqbal ◽  
Deji Akinwande ◽  
...  
Keyword(s):  
Surface Area ◽  
Low Cost ◽  
Bismuth Ferrite ◽  
Organic Dye ◽  
Two Dimensional ◽  
Electron Hole ◽  
Photocatalytic Application ◽  
Electron Hole Pair ◽  
Pair Generation ◽  
Photocatalytic Applications

<p>Nanohybrids, made up of Bismuth ferrites/Carbon allotropes, are extensively used in photocatalytic applications nowadays. Our work proposes a nanohybrid system composed of Bismuth ferrite nanoparticles with two-dimensional (2D) MXene sheets namely, the BiFeO<sub>3</sub> (BFO)/Ti<sub>3</sub>C<sub>2</sub> (MXene) nanohybrid for enhanced photocatalytic activity. We have fabricated the BFO/MXene nanohybrid using simple and low cost double solvent solvothermal method. The SEM and TEM images show that the BFO nanoparticles were attached onto the MXene surface and in the inter-layers of two-dimensional (2D) MXene sheets. The photocatalytic application is tested for the visible light irradiation which showed the highest efficiency among all pure-BFO based photocatalysts, i.e. 100% degradation in 42 min for organic dye (Congo Red) and colorless aqueous pollutant (acetophenone) in 150 min, respectively. The present BFO-based hybrid system exhibited the large surface area of 147 m<sup>2</sup>g<sup>-1</sup>measured via Brunauer-Emmett-Teller (BET) sorption-desorption technique, and is found to be largest among BFO and its derivatives. Also, the photoluminescence (PL) spectra indicate large electron-hole pair generation. Fast and efficient degradation of organic molecules is supported by both factors; larger surface area and lower electron-hole recombination rate. The BFO/MXene nanohybrid presented here is a highly efficient photocatalyst compared to other nanostructures based on pure BiFeO<sub>3</sub> which makes it a promising candidate for many future applications.</p>

scholarly journals Bioremediation of organic dyes using combination of plants ash

2019 ◽  
pp. 240-246
Author(s):  
Kaur Harpreet ◽  
Vandana Kamboj
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Methyl Orange ◽  
Crystal Violet ◽  
Congo Red ◽  
Organic Dyes ◽  
Low Cost ◽  
Sem Image ◽  
Orange Peels

Water is the most crucial thing to mankind and so its contamination by various agencies is posing a threat to the natural balance. So, in the present work, the efficiency of various adsorbents derived from plant waste, to remove different dyes from aqueous solution was evaluated. Parameters for study were contact time, concentration and pH. Various combinations of plant ashes were used for the study. It was found that adsorbent prepared from the combination of orange peels, pomegranate and banana peels ashes, exhibited good adsorption capacity for methylene blue, congo red and crystal violet. All these dyes were completely removed from the aqueous solution while methyl orange was not removed. Congo red was removed completely within 40 min of contact with the adsorbent while methyl orange took 3 hrs to be removed to the extent of 48% only. The adsorption coefficient of congo red was found to be 2.33 while value for methylene blue and crystal violet was 1 and 1.66 respectively. The characterization of adsorbent was done by Scanning Electron Microscopy and IR spectroscopy. SEM image revealed the surface of adsorbent to be made of differential pores. From the results it became evident that the low-cost adsorbent could be used as a replacement for costly traditional methods of removing colorants from water.

Synthesis of TiO2/RGO Nanocomposites by Hydrothermal Method and their Photocatalytic Activity Research

2015 ◽  
Vol 814 ◽  
pp. 178-181
Author(s):  
Jin Feng Leng ◽  
Ying Zi Wang ◽  
Xin Ying Teng ◽  
De Jiang Hu
Keyword(s):  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Hydrothermal Method ◽  
Separation Efficiency ◽  
Hydrothermal Reaction ◽  
Electron Hole ◽  
Graphene Surface ◽  
Uv Illumination ◽  
Reduced Graphene ◽  
Electron Hole Pair

The TiO2 reduced graphene oxide (TiO2/RGO) nanocomposites were synthetized by hydrothermal method. The microstructure and morphologies of them were characterized by XRD and SEM. The photocatalytic activity was investigated by the methyl orange photogradation under UV illumination. The results showed that GO sheets had wrinkles and folds, and anatase-structured TiO2 covered on graphene surface after hydrothermal reaction. Compared to the TiO2 nanoparticles, the TiO2/RGO nanocomposites display the higher photogradation efficiency. In 90 minutes, the gradation percentage of TiO2/RGO nanocomposites to methyl orange is 80%, higher than TiO2 nanoparticle (40%). This is attributed to the large surface area of TiO2/RGO nanocomposites and their improved separation efficiency of electron-hole pair.

scholarly journals Advances in metal-based vanadate compound photocatalysts: synthesis, properties and applications

2021 ◽  
Vol 1 (3) ◽  
pp. 151-168
Author(s):  
Asieh Akhoondi ◽  
Usisipho Feleni ◽  
Bhaskar Bethi ◽  
Azeez Olayiwola Idris ◽  
Akbar Hojjati-Najafabadi
Keyword(s):  
Visible Light ◽  
Low Cost ◽  
Synthesis Temperature ◽  
Solution Ph ◽  
Electron Hole ◽  
Preparation Methods ◽  
Ongoing Research ◽  
Synthesis Properties ◽  
Electron Hole Pair ◽  
Temperature Solution

Among the ongoing research on photocatalysis under visible-light, it has been shown that doped or hybrid catalysts are more active than a single catalyst alone. However, problems including visible light absorption, a low quantity of energetic sites on surfaces, and rapid recombination of the photo-electron hole pair produced by light have prohibited photocatalysts from being used in a practical and widespread manner. To overcome these problems, synthesis of nanostructure hybrid catalyst using several methods has attracted much attention. Several procedures have been suggested for the preparation of photocatalysts with the desired structure and morphology. Preparation methods similar to partial modification may lead to diverse structures and qualities. In this regard, the development of efficient, low-cost photocatalysts and rapid synthesis is the most important issues that should be considered. This review discusses various methods and mechanisms that work with the modification of vanadium compounds as photocatalysts to progress their photocatalytic efficiency. In addition, the effects of synthesis temperature, solution pH and concentration on the photocatalytic performance are also described in detail.

scholarly journals Fabrication of a stable light-activated and p/n type AgVO3/V2O5-TiO2 heterojunction for pollutants removal and photoelectrochemical water splitting

2021 ◽  
Author(s):  
Hai Yu ◽  
Zhang Miao ◽  
Yanfen Wang ◽  
Jianguo Lv ◽  
Lei Yang ◽  
...  
Keyword(s):  
Water Splitting ◽  
Photocurrent Density ◽  
Nanorod Arrays ◽  
Electron Hole ◽  
Photodegradation Efficiency ◽  
Conductive Glass ◽  
Electron Hole Pair ◽  
Layer V ◽  
Pollutants Removal ◽  
Efficiency Rate

Abstract In this study, TiO2 nanorod arrays (TiO2) was fabricated and modified with the AgVO3 quantum dots (QDs) decorate on interfacing few-layer V2O5 to form a heterojunction material for removal pollutants and photoelectrochemical (PCE) water splitting. The AgVO3/V2O5-TiO2 nanorod arrays (AgVO3/V2O5-TiO2) synthesized by the secondary hydrothermal method were loaded with conductive glass, which facilitated the formation of one-dimensional (1D) nanorod and p-n junction structures. Through instrumentations, to investigate the structural, morphological, optical, photocatalytic and PCE characteristics of the materials. The TiO2 modified by AgVO3 and V2O5 can significantly improve the visible light optical absorption, the reduce the electron-hole pair binding rate and shorten the band gap (3.07-1.41eV) of TiO2. The resulting photocurrent density (116uA/cm2 ) and photodegradation efficiency (rate constant, k = 0.025min− 1) of AgVO3/V2O5-TiO2 are approximately 20 (6uA/cm2) and 5 times (0.005min− 1) higher than those of bare TiO2, respectively. The AgVO3/V2O5-TiO2 achieved a current density of 10mA at an overpotential of 246.2mV and exhibited excellent oxygen evolution reaction (OER) performance. The systematic PEC experiments concluded that the optimized of the TiO2 interface by AgVO3 and V2O5 could promote the separation and transport of charge carriers.

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