scholarly journals Photocatalytic Applications of Metal Oxides for Sustainable Environmental Remediation

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 80
Author(s):  
Mir Sayed Shah Danish ◽  
Liezel L. Estrella ◽  
Ivy Michelle A. Alemaida ◽  
Anton Lisin ◽  
Nikita Moiseev ◽  
...  
Keyword(s):  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Environmental Remediation ◽  
Cost Effective ◽  
Water Systems ◽  
Treatment Technology ◽  
Rapid Urbanization ◽  
Wide Range ◽  
Photocatalytic Activities ◽  
Nanoparticles Of Metal Oxides

Along with industrialization and rapid urbanization, environmental remediation is globally a perpetual concept to deliver a sustainable environment. Various organic and inorganic wastes from industries and domestic homes are released into water systems. These wastes carry contaminants with detrimental effects on the environment. Consequently, there is an urgent need for an appropriate wastewater treatment technology for the effective decontamination of our water systems. One promising approach is employing nanoparticles of metal oxides as photocatalysts for the degradation of these water pollutants. Transition metal oxides and their composites exhibit excellent photocatalytic activities and along show favorable characteristics like non-toxicity and stability that also make them useful in a wide range of applications. This study discusses some characteristics of metal oxides and briefly outlined their various applications. It focuses on the metal oxides TiO2, ZnO, WO3, CuO, and Cu2O, which are the most common and recognized to be cost-effective, stable, efficient, and most of all, environmentally friendly for a sustainable approach for environmental remediation. Meanwhile, this study highlights the photocatalytic activities of these metal oxides, recent developments, challenges, and modifications made on these metal oxides to overcome their limitations and maximize their performance in the photodegradation of pollutants.

scholarly journals Electret formation in transition metal oxides by electrochemical amorphization

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Yong-Jin Kim ◽  
Chan-Ho Yang
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Charge Density ◽  
Electric Fields ◽  
Transition Metal Oxides ◽  
Degrees Of Freedom ◽  
Permanent Magnets ◽  
Underlying Mechanism ◽  
Diffusion Reaction ◽  
Wide Range

AbstractTransition metal oxides (TMOs) are an important class of materials that show a wide range of functionalities involving spin, charge, and lattice degrees of freedom. The strong correlation between electrons in d-orbitals and the multivalence nature give rise to a variety of exotic electronic states ranging from insulator to superconductor and cause intriguing phase competition phenomena. Despite a burst of research on the multifarious functionalities in TMOs, little attention has been paid to the formation and integration of an electret—a type of quasi-permanent electric field generator useful for nanoscale functional devices as an electric counterpart to permanent magnets. Here, we find that an electret can be created in LaMnO3 thin films by tip-induced electric fields, with a considerable surface height change, via solid-state electrochemical amorphization. The surface charge density of the formed electret area reaches ~400 nC cm−2 and persists without significant charge reduction for more than a year. The temporal evolution of the surface height, charge density, and electric potential are systematically examined by scanning probe microscopy. The underlying mechanism is theoretically analyzed based on a drift-diffusion-reaction model, suggesting that positively charged particles, which are likely protons produced by the dissociation of water, play crucial roles as trapped charges and a catalysis to trigger amorphization. Our finding opens a new horizon for multifunctional TMOs.

Electro-forming of vacancy-doped metal-SrTiO3-metal structures

2011 ◽  
Vol 1337 ◽  
Author(s):  
Florian Hanzig ◽  
Juliane Seibt ◽  
Hartmut Stoecker ◽  
Barbara Abendroth ◽  
Dirk C. Meyer
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Physical Vapor Deposition ◽  
Oxygen Vacancies ◽  
Vacuum Annealing ◽  
Metal Insulator ◽  
Metal Structures ◽  
Wide Range ◽  
Metal Insulator Metal

ABSTRACTResistance switching in metal – insulator - metal (MIM) structures with transition metal oxides as the insulator material is a promising concept for upcoming non-volatile memories. The electronic properties of transition metal oxides can be tailored in a wide range by doping and external fields. In this study SrTiO3 single crystals are subjected to high temperature vacuum annealing. The vacuum annealing introduces oxygen vacancies, which act as donor centers. MIM stacks are produced by physical vapor deposition of Au and Ti contacts on the front and rear face of the SrTiO3 crystal. The time dependent forming of the MIM stacks under an external voltage is investigated for crystals with varying bulk conductivities. For continued formation, the resistivity increases up to failure of the system where no current can be measured anymore and switching becomes impossible.

Impact of iron and manganese nano-metal-oxides on contaminant interaction and fortification potential in agricultural systems – a review

2019 ◽  
Vol 16 (6) ◽  
pp. 377 ◽  
Author(s):  
Elizabeth C. Gillispie ◽  
Stephen E. Taylor ◽  
Nikolla P. Qafoku ◽  
Michael F. Hochella Jr
Keyword(s):  
Metal Oxides ◽  
Targeted Delivery ◽  
Crop Production ◽  
Food Systems ◽  
Cost Effective ◽  
Agricultural Systems ◽  
Wide Range ◽  
Fe And Mn ◽  
Agricultural Contaminants ◽  
Future Work

Environmental contextNanominerals are more reactive than bulk minerals, a property that strongly influences the fate of nutrients and contaminants in soils and plants. This review discusses applications of Fe- and Mn-nano-oxides in agricultural systems and their potential to be used as fertiliser and contaminant adsorbents, while addressing potential phytotoxicity. We discuss areas where significant advances are needed, and provide a framework for future work. AbstractRising population growth and increase global food demand have made meeting the demands of food production and security a major challenge worldwide. Nanotechnology is starting to become a viable remediation strategy of interest in farming. Ultimately, it may be used as a sustainability tool in agricultural systems. In these roles, it could be used to increase the efficiency of techniques such as food monitoring, pathogen control, water treatment and targeted delivery of agrochemicals. In addition to these uses, nanoparticles, particularly nano-metal-oxides (NMOs), have been engineered to act as contaminant scavengers and could be applied to a wide range of systems. Numerous studies have investigated the scavenging ability of NMOs, but few have investigated them in this role in the context of agricultural and food systems. Within these systems, however, research has demonstrated the potential of NMOs to increase crop health and yield but few have studied using NMOs as sources of key micronutrients, such as Fe and Mn. In this review, we address previous research that has used Fe- and Mn-NMOs in agricultural systems, particularly the worldwide crop production of the four major staple foods – rice, wheat, maize and soybeans – highlighting their application as fertilisers and sorbents. Fe- and Mn-NMOs are strong candidates for immobilisation of agricultural contaminants in soils and, because they are naturally ubiquitous, they have the potential to be a cost-effective and sustainable technology compared with other remediation strategies.

scholarly journals A Review on the Properties and Applications of WO3 Nanostructure−Based Optical and Electronic Devices

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2136
Author(s):  
Yu Yao ◽  
Dandan Sang ◽  
Liangrui Zou ◽  
Qinglin Wang ◽  
Cailong Liu
Keyword(s):  
Electrical Properties ◽  
Transition Metal ◽  
Metal Oxides ◽  
Tungsten Oxide ◽  
Transition Metal Oxides ◽  
Electronic Devices ◽  
Information Storage ◽  
High Electron ◽  
Photochromic Properties ◽  
Wide Range

Tungsten oxide (WO3) is a wide band gap semiconductor with unintentionally n−doping performance, excellent conductivity, and high electron hall mobility, which is considered as a candidate material for application in optoelectronics. Several reviews on WO3 and its derivatives for various applications dealing with electrochemical, photoelectrochemical, hybrid photocatalysts, electrochemical energy storage, and gas sensors have appeared recently. Moreover, the nanostructured transition metal oxides have attracted considerable attention in the past decade because of their unique chemical, photochromic, and physical properties leading to numerous other potential applications. Owing to their distinctive photoluminescence (PL), electrochromic and electrical properties, WO3 nanostructure−based optical and electronic devices application have attracted a wide range of research interests. This review mainly focuses on the up−to−date progress in different advanced strategies from fundamental analysis to improve WO3 optoelectric, electrochromic, and photochromic properties in the development of tungsten oxide−based advanced devices for optical and electronic applications including photodetectors, light−emitting diodes (LED), PL properties, electrical properties, and optical information storage. This review on the prior findings of WO3−related optical and electrical devices, as well as concluding remarks and forecasts will help researchers to advance the field of optoelectric applications of nanostructured transition metal oxides.

scholarly journals John Goodenough and the Many Lives of Transition-Metal Oxides

2022 ◽  
Author(s):  
John M. Tranquada
Keyword(s):  
High Temperature ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Colossal Magnetoresistance ◽  
High Temperature Superconductivity ◽  
Mixed Valence ◽  
Wide Range ◽  
The Many

Abstract In honor of John Goodenough's centennial birthday, I discuss some of his insights into magnetism and the role of mixed valence in transition-metal oxides. His ideas form an important part of the continuing evolution of our understanding of these fascinating materials with a wide range of technologically-important functionalities. In particular, will mention connections to phenomena such as colossal magnetoresistance, enhanced thermopower, and high-temperature superconductivity.

The Role of Physical-Chemical Wastewater Treatment in the Mega-Cities of the Developing World

1999 ◽  
Vol 40 (4-5) ◽  
pp. 75-80 ◽  
Author(s):  
D. R. F. Harleman ◽  
S. Murcott
Keyword(s):  
Wastewater Treatment ◽  
Western Europe ◽  
Municipal Wastewater ◽  
Developing World ◽  
Cost Effective ◽  
Primary Treatment ◽  
Municipal Wastewater Treatment ◽  
Treatment Technology ◽  
Wide Range ◽  
Mega Cities

Should mega-cities of the developing world follow the development model of using municipal wastewater treatment technology of Western Europe and North America or is there an alternative “sustainable sanitation” approach? This paper tries to define the most efficient and cost-effective, minimum level of treatment needed to address one of the foremost problems of mega-cities, which is public health, putting forward the specific technological proposal of applying chemically enhanced primary treatment (CEPT). During the past ten years, the combination of low dosages of metal salts, such as ferric chloride, with very small dosages of anionic polymers, have resulted in an efficient single-stage treatment process known as CEPT. Some CEPT applications focus on increased suspended solids and/or BOD removal, increased flow capacity due to more rapid settling, while others are concerned with effluent disinfection by chlorine or ultraviolet light or with high levels of phosphorus removal through precipitation. A number of case studies with which the authors have been associated are used to illustrate a wide range of CEPT options that are particularly suitable for rapidly growing mega-cities. Examples are provided from Mexico City, Southern California, Hong Kong, Sao Paulo, and Rio de Janeiro.

A comparative study on photocatalytic activities of various transition metal oxides nanoparticles synthesized by wet chemical route

2021 ◽  
Vol 211 ◽  
pp. 181-195
Author(s):  
Muhammad Farooq Warsi ◽  
Nusrat Shaheen ◽  
Muhammad Ilyas Sarwar ◽  
Philips O. Agboola ◽  
Imran Shakir ◽  
...  
Keyword(s):  
Transition Metal ◽  
Comparative Study ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Chemical Route ◽  
Photocatalytic Activities ◽  
Wet Chemical ◽  
Wet Chemical Route

scholarly journals Nanostructure sensitization of transition metal oxides for visible-light photocatalysis

2014 ◽  
Vol 5 ◽  
pp. 696-710 ◽  
Author(s):  
Hongjun Chen ◽  
Lianzhou Wang
Keyword(s):  
Transition Metal ◽  
Visible Light ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Environmental Remediation ◽  
Carbon Nanostructures ◽  
Metal Nanostructures ◽  
Visible Light Photocatalysis ◽  
Visible Light Active ◽  
Underlying Mechanisms

To better utilize the sunlight for efficient solar energy conversion, the research on visible-light active photocatalysts has recently attracted a lot of interest. The photosensitization of transition metal oxides is a promising approach for achieving effective visible-light photocatalysis. This review article primarily discusses the recent progress in the realm of a variety of nanostructured photosensitizers such as quantum dots, plasmonic metal nanostructures, and carbon nanostructures for coupling with wide-bandgap transition metal oxides to design better visible-light active photocatalysts. The underlying mechanisms of the composite photocatalysts, e.g., the light-induced charge separation and the subsequent visible-light photocatalytic reaction processes in environmental remediation and solar fuel generation fields, are also introduced. A brief outlook on the nanostructure photosensitization is also given.

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

Problems with oxygen analysis in the system MgO-Al2O3-SiO2 with the electron microprobe

1992 ◽  
Vol 50 (2) ◽  
pp. 1624-1625
Author(s):  
Michel Fialin ◽  
Guy Rémond
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Electrostatic Charge ◽  
Carbon Layer ◽  
Sample Holder ◽  
Rock Matrix ◽  
Electrical Discharges ◽  
Thin Carbon ◽  
Beam Instabilities

Oxygen-bearing minerals are generally strong insulators (e.g. silicates), or if not (e.g. transition metal oxides), they are included within a rock matrix which electrically isolates them from the sample holder contacts. In this respect, a thin carbon layer (150 Å in our laboratory) is evaporated on the sections in order to restore the conductivity. For silicates, overestimated oxygen concentrations are usually noted when transition metal oxides are used as standards. These trends corroborate the results of Bastin and Heijligers on MgO, Al2O3 and SiO2. According to our experiments, these errors are independent of the accelerating voltage used (fig.l).Owing to the low density of preexisting defects within the Al2O3 single-crystal, no significant charge buildup occurs under irradiation at low accelerating voltage (< 10keV). As a consequence, neither beam instabilities, due to electrical discharges within the excited volume, nor losses of energy for beam electrons before striking the sample, due to the presence of the electrostatic charge-induced potential, are noted : measurements from both coated and uncoated samples give comparable results which demonstrates that the carbon coating is not the cause of the observed errors.

Sign in / Sign up

Export Citation Format

Share Document