Search query: research of photocatalyst

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abstract: The creation of core shell nanocomposites (CSNs) has attracted considerable attention and developed into an increasingly important research area at the frontier of advanced materials chemistry. CSNs, which are nanoscaled assemblies with a chemical composition that is different on the surface compared to the core region, have found versatile applications in many fields, such as electrooptics, quantum dots, microscopy labels, drug delivery, chemical sensors, nanoreactors and catalysis. This review is primarily focused on the applications of metal core@semiconductor shell nanocomposites in heterogeneous photocatalysis, including photocatalytic nonselective processes for environmental remediation, selective organic transformations to fine chemicals and water splitting to clean hydrogen energy. It is hoped that this minireview can inspire multidisciplinary research interest in the precisely morphology controlled synthesis of a variety of metal core@semiconductor shell nanoassemblies and their wide applications in the realm of heterogeneous photocatalysis.
author_names: Nan Zhang

Siqi Liu

Yi-Jun Xu
title: Recent progress on metal core@semiconductor shell nanocomposites as a promising type of photocatalyst.
venue: Nanoscale
year: 2012

abstract: Background: Antibiotics such as ciprofloxacin (CIP) are even more important in bacterial resistance, even at low concentrations. The aim of this research was to synthesize CuFe2 O4 @methylcellulose (MC) as a new nano photocatalyst for degradation of CIP from aqueous solution. Methods: The nano photocatalyst (CuFe2 O4 @MC) was characterized by FESEM, energy dispersive spectroscopy (EDS) X ray diffraction (XRD) and Fourier transform infrared (FTIR) thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM) Powder XRD and EDS analysis confirmed the formation of pure phase spinel ferrites. After CuFe2 O4 @MC characterization, the effective parameters in removal efficiency of CIP such as reaction time, initial antibiotic concentration, pH, photocatalyst loading, and degradation kinetic were investigated and conditions were optimized. Then, CIP degradation experiments were conducted on the real sample in the optimal conditions. The removal of chemical oxygen demand (COD) was determined under optimum conditions. Results: The structural characterization of the magnetic nanobiocomposite showed that it is in nanoscale, ferromagnetic property, and thermal stability. The optimal conditions were obtained at pH 7, irradiation time (90 minutes) photocatalyst loading (0.2 g) and initial concentration of CIP (3 mg/L) The removal efficiency of CIP in the optimal conditions was obtained as 80.74% and 72.87% from the synthetic and real samples, respectively. The removal of COD was obtained as 68.26% in this process. The evaluation of kinetic linear models showed that the photocatalytic degradation process was fitted by pseudo first order kinetic model and Langmuir Hinshelwood. CuFe2 O4 @MC photocatalyst had a good stability and reusability for the fourth runs. Conclusion: The photocatalytic degradation of CIP from aqueous media with CuFe2 O4 @MC photocatalyst has a high efficiency, which can be used in the treatment of pharmaceutical wastewaters.
author_names: Alireza Nasiri

Fatemeh Tamaddon

Mohammad Hossein Mosslemin

Majid Amiri Gharaghani

Ali Asadipour
title: Magnetic nano biocomposite CuFe2 O4 @methylcellulose (MC) prepared as a new nano photocatalyst for degradation of ciprofloxacin from aqueous solution
venue: Environmental Health Engineering and Management
year: 2019

abstract: Indiscriminate consumption of antibiotics, their discharge into the environment, and the development of resistant genes in a natural ecosystem are ever increasing global threats. Metronidazole is applied to treat infection diseases caused by anaerobic bacteria and protozoa. In this research, TiO2/Fe+3 was used as a heterogeneous nano photocatalyst for the degradation of metronidazole with UV C radiation as the energy source. Parameters tested in the removal process were pH 3, 7, and 11; antibiotic concentration of 80 mg/L; contact times of 30, 60, 90, and 120 min; and nano photocatalyst of TiO2/Fe+3 with concentrations of 30, 60, 90, 250, 500, 750, and 1000 mg/L. The photocatalytic degradation kinetics of metronidazole was studied. Optimal conditions were achieved on synthetic solutions; then, all experiments were performed on wastewater from the pharmaceutical industry. Antibiotic concentrations were measured using an HPLC device. All tests were replicated three times according to the standard methods of water and wastewater experiments, the 20th edition. Data were analyzed using SPSS 19 and the statistical test ANOVA. The optimal conditions for removing metronidazole from synthetic solution included, 500 mg/L for nano photocatalyst concentration, pH 11 and 120 min contact time. Removal efficiency of antibiotic under optimal conditions was 97% from synthetic solutions and 69.85% from pharmaceutical wastewater. Finally, Fe+3 TiO2/UV C were identified as a promising technique for the removal of metronidazole with high efficiency from aqueous solutions.
author_names: Mohammad Malakootian

Narges Olama

Alireza Nasiri
title: Photocatalytic degradation of metronidazole from aquatic solution by TiO2 doped Fe3+ nano photocatalyst
venue: International Journal of Environmental Science and Technology
year: 2018

abstract: Many reviews are written on this interesting visible light active polymeric semiconductor material, the graphitic carbon nitride (g C3N4) Yet the ever expanding volume of the ongoing research on this materials has inspired us to compile this review, especially on its nanoscale architectures of noble metal free photocatalyst systems. From the viewpoint of sustainable development, an economical photocatalyst which is made up of abundant elements e. g. C and N has a good prospect for large scale applications. Stability of the photocatalyst material under the experimental conditions is essential for its repeated usage, however, many semiconductors sought for visible light driven reaction, particularly sulfides and nitrides are in a compromising situation. However, g C3N4 has high chemical and photo stability besides its high activity under visible light irradiation. Furthermore, solely semiconductor materials have the intrinsic problem of recombination of photogenerated electron hole pairs. To overcome this problem, loading of the semiconductor with a co catalyst, usually a noble metal is a common practice for transfer of electron and thus avoiding the recombination. Development of a noble metal free photocatalyst systems is essentially important for sustainable applications. Hence, the construction of a hybrid composite structure is interesting in the separation of photogenerated charge carriers. Besides diminishing the rate of recombination, the heterostructures are constructed for harnessing a wider spectrum of sunlight. In contrast to bulk semiconductors, their nanoscale counterpart offers a larger number of active sites along with interesting electrical and optical properties. Importantly, construction of extensive junctions between nanomaterials greatly enhance the separation of charges and consequently improve their photocatalytic efficiency. Usually, the stability of materials is compromised with the reduction of size to nano level, however, g C3N4 and its nanomaterials demonstrate exceptional recycling in photocatalytic testing. One of the most important interests in controlling nanoparticle size, shape and composition is to develop noble metal free photocatalyst systems. Here in this review, we have compiled research on all the various applications of noble metal free nanoscale photocatalyst systems based on g C3N4. By the end, we conclude the research topic and put forward future perspectives for further developments in designing practicable photocatalyst systems.
author_names: Dilshad Masih

Yuanyu Ma

Sohrab Rohani
title: Graphitic C3N4 based noble metal free photocatalyst systems: A review
year: 2017

abstract: Photocatalyst arrays of a number of metal oxides were prepared by dispensing metal precursor solutions onto fluorine doped tin oxide coated glass followed by annealing at 500 degC for 3 h. These were screened by scanning electrochemical microscopy with a scanning optical fiber, and the results showed that all Sn doped Cd In Bi, Zn In, and W Cd oxide photocatalysts produced enhanced photocurrents for specific metal ratios. The products of the photoelectrochemical (PEC) reaction could be detected electrochemically by a Au ring on the optical fiber. The PEC properties of larger electrodes were investigated, and the Zn In and W Cd oxide photocatalysts showed a much higher photoactivity than Sn doped Cd In Bi. Even without catalysts, they showed visible light response for water oxidation to oxygen.
author_names: Wen Liu

Heechang Ye

Allen J Bard
title: Screening of Novel Metal Oxide Photocatalysts by Scanning Electrochemical Microscopy and Research of Their Photoelectrochemical Properties
year: 2010

abstract: Visible light driven water splitting using cheap and robust photocatalysts is one of the most exciting ways to produce clean and renewable energy for future generations. Cutting edge research within the field focuses on so called "Z scheme" systems, which are inspired by the photosystem II photosystem I (PSII/PSI) coupling from natural photosynthesis. A Z scheme system comprises two photocatalysts and generates two sets of charge carriers, splitting water into its constituent parts, hydrogen and oxygen, at separate locations. This is not only more efficient than using a single photocatalyst, but practically it could also be safer. Researchers within the field are constantly aiming to bring systems toward industrial level efficiencies by maximizing light absorption of the materials, engineering more stable redox couples, and also searching for new hydrogen and oxygen evolution cocatalysts. This review provides an in depth survey of relevant Z schemes from past to present, with particular focus on mechanistic breakthroughs, and highlights current state of the art systems which are at the forefront of the field.
author_names: Yiou Wang

Hajime Suzuki

Jijia Xie

Osamu Tomita

David James Martin

Masanobu Higashi

Dan Kong

Ryu Abe

Junwang Tang
title: Mimicking Natural Photosynthesis: Solar to Renewable H2 Fuel Synthesis by Z Scheme Water Splitting Systems
venue: Chemical reviews
year: 2018

abstract: Today, a major issue about water pollution is the residual dyes from different sources (e.g. textile industries, paper and pulp industries, dye and dye intermediates industries, pharmaceutical industries, tannery and craft bleaching industries, etc. and a wide variety of persistent organic pollutants have been introduced into our natural water resources or wastewater treatment systems. In fact, it is highly toxic and hazardous to the living organism; thus, the removal of these organic contaminants prior to discharge into the environment is essential. Varieties of techniques have been employed to degrade those organic contaminants and advanced heterogeneous photocatalysis involving zinc oxide (ZnO) photocatalyst appears to be one of the most promising technology. In recent years, ZnO photocatalyst have attracted much attention due to their extraordinary characteristics. The high efficiency of ZnO photocatalyst in heterogeneous photocatalysis reaction requires a suitable architecture that minimizes electron loss during excitation state and maximizes photon absorption. In order to further improve the immigration of photo induced charge carriers during excitation state, considerable effort has to be exerted to further improve the heterogeneous photocatalysis under UV/visible/solar illumination. Lately, interesting and unique features of metal doping or binary oxide photocatalyst system have gained much attention and became favourite research matter among various groups of scientists. It was noted that the properties of this metal doping or binary oxide photocatalyst system primarily depend on the nature of the preparation method and the role of optimum dopants content incorporated into the ZnO photocatalyst. Therefore, this paper presents a critical review of recent achievements in the modification of ZnO photocatalyst for organic contaminants degradation.
author_names: Kian Mun Lee

Chin Wei Lai

Koh Sing Ngai

Joon Ching Juan
title: Recent developments of zinc oxide based photocatalyst in water treatment technology: A review.
venue: Water research
year: 2016

abstract: As a fascinating conjugated polymer, graphitic carbon nitride (g C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal free and visible light responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and "earth abundant" nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g C3N4 and g C3N4 based nanocomposites, including (1) nanoarchitecture design of bare g C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template free synthesis routes, (2) functionalization of g C3N4 at an atomic level (elemental doping) and molecular level (copolymerization) and (3) modification of g C3N4 with well matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The construction and characteristics of each classification of the heterojunction system will be critically reviewed, namely metal g C3N4, semiconductor g C3N4, isotype g C3N4/g C3N4, graphitic carbon g C3N4, conducting polymer g C3N4, sensitizer g C3N4, and multicomponent heterojunctions. The band structures, electronic properties, optical absorption, and interfacial charge transfer of g C3N4 based heterostructured nanohybrids will also be theoretically discussed based on the first principles density functional theory (DFT) calculations to provide insightful outlooks on the charge carrier dynamics. Apart from that, the advancement of the versatile photoredox applications toward artificial photosynthesis (water splitting and photofixation of CO2) environmental decontamination, and bacteria disinfection will be presented in detail. Last but not least, this comprehensive review will conclude with a summary and some invigorating perspectives on the challenges and future directions at the forefront of this research platform. It is anticipated that this review can stimulate a new research doorway to facilitate the next generation of g C3N4 based photocatalysts with ameliorated performances by harnessing the outstanding structural, electronic, and optical properties for the development of a sustainable future without environmental detriment.
author_names: Wee-Jun Ong

Lling-Lling Tan

Yun Hau Ng

Siek-Ting Yong

Siang-Piao Chai
title: Graphitic Carbon Nitride (g C3N4) Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?
venue: Chemical reviews
year: 2016

abstract: Hydrogen from direct splitting of water molecules using photons is reckoned to be a sustainable and renewable energy solution for the post fossil fuel era. Efficient photocatalysts, including metal free photocatalysts, are key determinants of cost effective hydrogen generation at a large scale. The search for new materials that are metal free is therefore ongoing. Recently, 2D phosphorene, a phosphorus analogue of graphene, has been added as a new semiconductor to the family of monolayer flatland materials. In this review, we focus on analysing the fundamental electronic, optical and chemical properties of 2D phosphorene and assess its suitability as a metal free water splitting photocatalyst. We also critically analyse its stability against claims from environmental antagonists and attempt to predict its future as a photocatalyst. This review provides timely information for researchers, scientists and professionals devoted to materials research for photocatalysis.
author_names: Mohammad Ziaur Rahman

Chi Wai Kwong

Kenneth Davey

Shizhang Qiao
title: 2D phosphorene as a water splitting photocatalyst: fundamentals to applications
year: 2016

abstract: Among three polymorphs of TiO2, the brookite is the least known phase in many aspects of its properties and photoactivities (especially comparable to anatase and rutile) because it is the rarest phase to be synthesized in the standard environment among the TiO2 polymorphs. In this study, we address the unrevealed photocatalytic properties of pure brookite TiO2 film as an environmental photocatalyst. Highly crystalline brookite nanostructures were synthesized on titanium foil using a well designed hydrothermal reaction, without harmful precursors and selective etching of anatase, to afford pure brookite. The photocatalytic degradation of rhodamine B, tetramethylammonium chloride, and 4 chlorophenol on UV illuminated pure brookite were investigated and compared with those on anatase and rutile TiO2. The present research explores the generation of OH radicals as main oxidants on brookite. In addition, tetramethylammonium, as a mobile OH radical indicator, was degraded over both pure anatase and brookite phases, but not rutile. The brookite phase showed much higher photoactivity among TiO2 polymorphs, despite its smaller surface area compared with anatase. This result can be ascribed to the following properties of the brookite TiO2 film: (i) the higher driving force with more negative flat band potential, (ii) the efficient charge transfer kinetics with low resistance, and (iii) the generation of more hydroxyl radicals, including mobile OH radicals. The brookite nanostructured TiO2 electrode facilitates photocatalyst collection and recycling with excellent stability, and readily controls photocatalytic degradation rates with facile input of additional potential.
author_names: Mingi Choi

Jonghun Lim

Minki Baek

Wonyong Choi

Wooyul Kim

Kijung Yong
title: Investigating the Unrevealed Photocatalytic Activity and Stability of Nanostructured Brookite TiO2 Film as an Environmental Photocatalyst.
venue: ACS applied materials interfaces
year: 2017