Recent advancements of g-C3N4-based magnetic photocatalysts towards the degradation of organic pollutants: a review

Reaction Medium ◽

Heterogeneous Photocatalysis ◽

Working Mechanism ◽

Electron Hole ◽

Practical Applications ◽

Earth Abundant ◽

Enhance Efficiency ◽

Abstract Heterogeneous photocatalysis premised on advanced oxidation processes (AOPs) has witnessed a broad application perspective, including water purification and environmental remediation. In particular, the graphitic carbon nitride (g-C3N4), an earth-abundant metal-free conjugated polymer, has acquired extensive application scope and interdisciplinary consideration owing to its outstanding structural and physicochemical properties. However, several issues such as the high recombination rate of the photo-generated electron-hole pairs (EHP), smaller specific surface area (SSA), and lower electrical conductivity curtail the catalytic efficacy of bulk g-C3N4. Another challenging task is separating the catalyst from the reaction medium, limiting their reusability and practical applications. Therefore, several methodologies are adopted strategically to tackle these issues. Attention is being paid, especially to the magnetic nanocomposites-based catalysts to enhance efficiency and proficient reusability property. This review summarizes the latest progress related to the design and development of magnetic g-C3N4-based nanocomposites (NCs) and their utilization in photocatalytic systems. The usefulness of the semiconductor heterojunctions on the catalytic activity, working mechanism, and degradation of pollutants are discussed in detail. The major challenges and prospects of using magnetic g-C3N4-based NCs for photocatalytic applications are highlighted in this report.

Nitrogen-doped Carbon Nanospheres-Modified Graphitic Carbon Nitride with Outstanding Photocatalytic Activity

Nano-Micro Letters ◽

10.1007/s40820-019-0358-x ◽

2020 ◽

Vol 12 (1) ◽

Cited By ~ 6

Author(s):

Qiaoran Liu ◽

Hao Tian ◽

Zhenghua Dai ◽

Hongqi Sun ◽

Jian Liu ◽

...

Keyword(s):

Density Functional ◽

Carbon Nitride ◽

Graphitic Carbon ◽

Graphitic Carbon Nitride ◽

Carbon Nanospheres ◽

Electron Hole ◽

Practical Applications ◽

Nitrogen Doped ◽

Nitrogen Doped Carbon

AbstractMetals and metal oxides are widely used as photo/electro-catalysts for environmental remediation. However, there are many issues related to these metal-based catalysts for practical applications, such as high cost and detrimental environmental impact due to metal leaching. Carbon-based catalysts have the potential to overcome these limitations. In this study, monodisperse nitrogen-doped carbon nanospheres (NCs) were synthesized and loaded onto graphitic carbon nitride (g-C3N4, GCN) via a facile hydrothermal method for photocatalytic removal of sulfachloropyridazine (SCP). The prepared metal-free GCN-NC exhibited remarkably enhanced efficiency in SCP degradation. The nitrogen content in NC critically influences the physicochemical properties and performances of the resultant hybrids. The optimum nitrogen doping concentration was identified at 6.0 wt%. The SCP removal rates can be improved by a factor of 4.7 and 3.2, under UV and visible lights, by the GCN-NC composite due to the enhanced charge mobility and visible light harvesting. The mechanism of the improved photocatalytic performance and band structure alternation were further investigated by density functional theory (DFT) calculations. The DFT results confirm the high capability of the GCN-NC hybrids to activate the electron–hole pairs by reducing the band gap energy and efficiently separating electron/hole pairs. Superoxide and hydroxyl radicals are subsequently produced, leading to the efficient SCP removal.

Upscaling Anodic Synthesis of TiO2 Nanotubes Film as Potential Material for Photoelectrocatalytic Applications: Influence of Electrolyte Overheating and Aging on Nanotube Morphology and Stability

Journal of Photocatalysis ◽

10.2174/2665976x01999200603164023 ◽

2020 ◽

Vol 1 (1) ◽

pp. 43-49

Author(s):

Cédric Marien ◽

Marie Le Pivert ◽

Ahmad Dirany ◽

Patrick Drogui ◽

Thomas Cottineau ◽

...

Keyword(s):

Tio2 Nanotubes ◽

Large Scale ◽

Heat Dissipation ◽

Electrochemical Cell ◽

Heterogeneous Photocatalysis ◽

Electron Hole ◽

Practical Applications ◽

Precise Control ◽

Real Wastewater ◽

Anodic Synthesis

Background: Among Advanced oxidation processes, heterogeneous photocatalysis have a great interest, because it uses only light has a source of energy. One of the main limiting processes in photocatalysis is the high probability of electron-hole pair’s recombination in the volume or at the surface of the photocatalyst particles. TiO2 nanotubes grown by anodic synthesis are widely studied because of the large number of potential practical applications especially in photocatalytic or photoelectrochemical applications. However, the preparation of these electrodes at large scale is still challenging due to some technological obstacles such as the electrochemical cell design or the precise control of nanotubes morphology, especially regarding electrolyte ageing and overheating during the synthesis. Objective: This study examines the electrochemical synthesis of TiO2 nanotubes supported on large titanium electrodes. Methods and Results: By understanding heat dissipation phenomenon during the synthesis, an optimized electrochemical cell was designed to prepare 6x4 cm 2 anodes. Then we aimed to control precisely the length of the nanotubes independently of electrolyte ageing. Indeed, It was previously observed that the electrolyte composition evolves (ageing) during the nanotubes synthesis and hence leads to nonreproducible nanotubes morphologies under time-controlled potentiostatic anodization conditions. Conclusion and Perspectives: To overcome this issue, we developed a Coulometric approach that allows to synthesize, reusing the same electrolyte, several electrodes with a great precision and reproducibility on the length of the nanotubes (2,7 μm ± 160 nm) despite electrolyte ageing. Subsequently, these electrodes can be integrated in a photocatalytic or photoelectrocatalytic process in a real wastewater treatment sector would be very relevant.

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

10.26434/chemrxiv.8192375.v1 ◽

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 ◽

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 BiFeO3 (BFO)/Ti3C2 (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 m2g-1measured 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 BiFeO3 which makes it a promising candidate for many future applications.

Oxide-based catalysis: tailoring surface structures via organic ligands and related interfacial charge carrier for environmental remediation

RSC Advances ◽

10.1039/d1ra01782a ◽

2021 ◽

Vol 11 (31) ◽

pp. 19059-19069

Author(s):

S. Harish ◽

S. Athithya ◽

V. Shivani ◽

S. Ponnusamy ◽

M. Shimomura ◽

...

Keyword(s):

Charge Carrier ◽

Structure Formation ◽

Organic Ligands ◽

Surface Structures ◽

Hierarchical Nanostructures ◽

Amine Ligands ◽

Interfacial Charge ◽

Hierarchical nanostructures of ZnO/CuO and the effects of amine ligands on their structure, formation and photocatalytic applications were investigated.

Preparation and photocatalytic performance of metallic Nb0.9Ta0.1S2/2D-C3N4 composite

Oxford Open Materials Science ◽

10.1093/oxfmat/itab005 ◽

2020 ◽

Vol 1 (1) ◽

Author(s):

Hanxiang Chen ◽

Jianjian Yi ◽

Zhao Mo ◽

Yanhua Song ◽

Wenshu Yang ◽

...

Keyword(s):

Separation Efficiency ◽

Low Cost ◽

Metal Sulfide ◽

Electron Hole ◽

Practical Applications ◽

Energy And Environment ◽

Photocatalytic Application ◽

Light Utilization ◽

Ternary Metal ◽

Key Issues

Abstract Photocatalysis technology has potential application in the field of energy and environment. How to expand visible light utilization and promote the separation efficiency of the carriers are the key issues for the high active photocatalysts preparation and future practical applications. In this work, a ternary metal sulfide Nb0.9Ta0.1S2 was prepared and used as an electron collector in the photocatalytic application. As a result, the generated electrons are quickly transferred to the surface of the composite to participate in the reaction. It was demonstrated that the photocatalytic activity of 2D-C3N4 was enhanced after the modification of Nb0.9Ta0.1S2. The Nb0.9Ta0.1S2/2D-C3N4 composite material was synthesized by solvothermal method. The composition of 5% Nb0.9Ta0.1S2/2D-C3N4 showed the highest H2 evolution rate of 1961.6 μmolg−1h−1, which was 6.6 times that of 2D-C3N4. The 15% Nb0.9Ta0.1S2/2D-C3N4 exhibited the best activity in Rhodamine B degradation rate of 97% in 2 h, which is 50% higher than that of 2D-C3N4. Nb0.9Ta0.1S2/2D-C3N4 can be used as electron trap to promote the effective separation of electron–hole pairs. This work provides benchmarks in exploring low-cost and efficient cocatalyst.

A Review of Photoelectrocatalytic Reactors for Water and Wastewater Treatment

Water ◽

10.3390/w13091198 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1198

Author(s):

Stuart McMichael ◽

Pilar Fernández-Ibáñez ◽

John Anthony Byrne

Keyword(s):

Chemical Compounds ◽

Research Area ◽

Heterogeneous Photocatalysis ◽

Semiconducting Materials ◽

Electron Hole ◽

Water And Wastewater Treatment ◽

Aqueous Environments ◽

Different Types ◽

Water And Wastewater ◽

Electrical Bias

The photoexcitation of suitable semiconducting materials in aqueous environments can lead to the production of reactive oxygen species (ROS). ROS can inactivate microorganisms and degrade a range of chemical compounds. In the case of heterogeneous photocatalysis, semiconducting materials may suffer from fast recombination of electron–hole pairs and require post-treatment to separate the photocatalyst when a suspension system is used. To reduce recombination and improve the rate of degradation, an externally applied electrical bias can be used where the semiconducting material is immobilised onto an electrically conducive support and connected to a counter electrode. These electrochemically assisted photocatalytic systems have been termed “photoelectrocatalytic” (PEC). This review will explain the fundamental mechanism of PECs, photoelectrodes, the different types of PEC reactors reported in the literature, the (photo)electrodes used, the contaminants degraded, the key findings and prospects in the research area.

SnS2/TiO2 Nanocomposites for Hydrogen Production and Photodegradation Under Extended Solar Irradiation

Catalysts ◽

10.3390/catal11050589 ◽

2021 ◽

Vol 11 (5) ◽

pp. 589

Author(s):

Sivagowri Shanmugaratnam ◽

Balaranjan Selvaratnam ◽

Aravind Baride ◽

Ranjit Koodali ◽

Punniamoorthy Ravirajan ◽

...

Keyword(s):

Methylene Blue ◽

Photocatalytic Activity ◽

Hydrogen Evolution ◽

High Performance ◽

Degradation Mechanism ◽

Solar Irradiation ◽

Earth Abundant ◽

Improved Performance ◽

Chalcogenide Materials

Earth–abundant transition metal chalcogenide materials are of great research interest for energy production and environmental remediation, as they exhibit better photocatalytic activity due to their suitable electronic and optical properties. This study focuses on the photocatalytic activity of flower-like SnS2 nanoparticles (composed of nanosheet subunits) embedded in TiO2 synthesized by a facile hydrothermal method. The materials were characterized using different techniques, and their photocatalytic activity was assessed for hydrogen evolution reaction and the degradation of methylene blue. Among the catalysts studied, 10 wt. % of SnS2 loaded TiO2 nanocomposite shows an optimum hydrogen evolution rate of 195.55 µmolg−1, whereas 15 wt. % loading of SnS2 on TiO2 exhibits better performance against the degradation of methylene blue (MB) with the rate constant of 4.415 × 10−4 s−1 under solar simulated irradiation. The improved performance of these materials can be attributed to the effective photo-induced charge transfer and reduced recombination, which make these nanocomposite materials promising candidates for the development of high-performance next-generation photocatalyst materials. Further, scavenging experiments were carried out to confirm the reactive oxygen species (ROS) involved in the photocatalytic degradation. It can be observed that there was a 78% reduction in the rate of degradation when IPA was used as the scavenger, whereas around 95% reduction was attained while N2 was used as the scavenger. Notably, very low degradation (<5%) was attained when the dye alone was directly under solar irradiation. These results further validate that the •OH radical and the superoxide radicals can be acknowledged for the degradation mechanism of MB, and the enhancement of degradation efficiency may be due to the combined effect of in situ dye sensitization during the catalysis and the impregnation of low bandgap materials on TiO2.

Study on Water Cushion Belt Conveyor

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1016.14 ◽

2014 ◽

Vol 1016 ◽

pp. 14-18

Author(s):

Xian Wei Liu ◽

Jia Sheng Wang ◽

Lan Tao Wu ◽

Xin Zhang ◽

Hua Cheng

Keyword(s):

Reynolds Equation ◽

Belt Conveyor ◽

Working Mechanism ◽

Film Properties ◽

Practical Applications ◽

Lubrication Equation ◽

Start Up ◽

New Type ◽

Air Cushion ◽

Lubricating Mechanism

Based on air cushion belt conveyor, a new type of belt conveyor named water cushion belt conveyor is proposed. It has a wide scope of applications for its features such as stability and reliability, capability of full load start-up, and environment-friendliness. This paper studies the working mechanism and lubricating mechanism of the water cushion belt conveyor. The basic lubrication equation of the water cushion is deduced from the universal form of the Reynolds equation used to study the pressure film properties of the water cushion. The design of the key part of the water cushion device is described in details. The research can be taken as a reference in practical applications.

Multifunctional Ni-Mg-Bimetal-Activated Zn(O,S) for Hydrogen Generation and Environmental Remediation with Simulated Solar-Light Irradiation

Catalysis Science & Technology ◽

10.1039/d1cy00977j ◽

2021 ◽

Author(s):

Hairus Abdullah ◽

Hardy Shuwanto ◽

Dong-Hau Kuo

Keyword(s):

Hydrogen Production ◽

Hexavalent Chromium ◽

Chemical Transformation ◽

Hydrogen Generation ◽

Hydrogenation Reaction ◽

Light Irradiation ◽

Simulated Solar Light ◽

Solar Light Irradiation ◽

Ni-Mg-Bimetal doped Zn(O,S) has been synthesized, characterized, and tested for several photocatalytic applications such as hydrogen production, hydrogenation reaction for chemical transformation, detoxification of hexavalent chromium, and mixed dye (MB...

A high-spin ground-state donor-acceptor conjugated polymer

Science Advances ◽

10.1126/sciadv.aav2336 ◽

2019 ◽

Vol 5 (5) ◽

pp. eaav2336 ◽

Cited By ~ 17

Author(s):

A. E. London ◽

H. Chen ◽

M. A. Sabuj ◽

J. Tropp ◽

M. Saghayezhian ◽

...

Keyword(s):

Organic Semiconductors ◽

High Spin ◽

Ground State ◽

Conjugated Polymer ◽

Organic Materials ◽

Energy Gap ◽

Light Element ◽

Paramagnetic Resonance ◽

Practical Applications ◽

Polymer Semiconductor

Interest in high-spin organic materials is driven by opportunities to enable far-reaching fundamental science and develop technologies that integrate light element spin, magnetic, and quantum functionalities. Although extensively studied, the intrinsic instability of these materials complicates synthesis and precludes an understanding of how fundamental properties associated with the nature of the chemical bond and electron pairing in organic materials systems manifest in practical applications. Here, we demonstrate a conjugated polymer semiconductor, based on alternating cyclopentadithiophene and thiadiazoloquinoxaline units, that is a ground-state triplet in its neutral form. Electron paramagnetic resonance and magnetic susceptibility measurements are consistent with a high-to-low spin energy gap of 9.30 × 10−3 kcal mol−1. The strongly correlated electronic structure, very narrow bandgap, intramolecular ferromagnetic coupling, high electrical conductivity, solution processability, and robust stability open access to a broad variety of technologically relevant applications once thought of as beyond the current scope of organic semiconductors.