نتایج جستجو برای: hematite

تعداد نتایج: 2566  

2016
David W. Jenkins Alexis K. Ault James P. Evans

This project serves as a literature review on the transformation and synthesis of magnetite from hematite under hydrothermal conditions as well as with Pulsed Laser Deposition (PLD) and milling. Magnetite forms over a similar range of elevated temperatures regardless the method that is used to synthesize it, including nonheterogeneous, loosely controlled environments such as a ceramics kiln. Ba...

Journal: :Physical chemistry chemical physics : PCCP 2015
Nicola Dalle Carbonare Stefano Carli Roberto Argazzi Michele Orlandi Nicola Bazzanella Antonio Miotello Stefano Caramori Carlo A Bignozzi

Different approaches have been explored to increase the water oxidation activity of nanostructured hematite (α-Fe2O3) photoanodes, including doping with various elements, surface functionalization with both oxygen evolving catalysts (OEC) and functional overlayers and, more recently, the introduction of ultrathin oxide underlayers as tunneling back contacts. Inspired by this latter strategy, we...

Journal: :Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology 2009
Serge Chiron Stéphane Barbati Swapan Khanra Binay K Dutta Marco Minella Claudio Minero Valter Maurino Ezio Pelizzetti Davide Vione

Bicarbonate enhances the transformation of phenol upon irradiation of hematite, and phenol nitration upon irradiation of both nitrate and nitrite. Hematite under irradiation is able to oxidise the carbonate ion to the CO3-. radical, which in turn oxidises phenol to the phenoxyl radical faster compared to the direct photo-oxidation of phenol by hematite. The formation of CO3-. from hematite and ...

2016
Rui Zhang Cristian Necula David Heslop Junsheng Nie

Magnetic paleoclimatic records often represent mixed environmental signals. Unmixing these signals may improve our understanding of the paleoenvironmental information contained within these records, but such a task is challenging. Here we report an example of numerical unmixing of magnetic hysteresis data obtained from Chinese loess and red clay sequences. We find that the mixed magnetic assemb...

Journal: :Geophysical Research Letters 2023

Abstract Goethite/hematite ratios in soils are widely used to reconstruct past climatic changes, but their accurate measurements have remained challenging due the matrix effect. Here we present a new method for measuring soil goethite/hematite by characterizing band position of electron pair transition (EPT) based on diffuse reflectance spectra processed continuum removal. We introduce “half‐ba...

Journal: :Molecules 2016
Yuchao Zhang Hongwei Ji Wanhong Ma Chuncheng Chen Wenjing Song Jincai Zhao

As one of the most promising materials for solar water oxidation, hematite has attracted intense research interest for four decades. Despite their desirable optical band gap, stability and other attractive features, there are great challenges for the implementation of hematite-based photoelectrochemical cells. In particular, the extremely low electron mobility leads to severe energy loss by ele...

2006
Ivan JURKOVIC

In the Dusina area, which is built up of Lower Palaeozoic metasediments, Devonian carbonate complex and Upper Palaeozoic metarhyolites unconformably overlain by Upper Permian sediments, numerous ore occurrences have been investigated: (a) "stratabound" metamorphic hematite deposits in the pre-Devonian metasediments; (b) epigenetic veins and pipes of barite (& calcite) with accessory Hg-tetrahed...

Journal: :Nanoscale 2017
Zachary S Fishman Yulian He Ke R Yang Amanda W Lounsbury Junqing Zhu Thanh Minh Tran Julie B Zimmerman Victor S Batista Lisa D Pfefferle

Understanding how nano-dimensionality impacts iron oxide based catalysis is central to a wide range of applications. Here, we focus on hematite nanosheets, nanowires and nanoparticles as applied to catalyze the reverse water gas shift (RWGS) probe reaction. We introduce a novel approach to synthesize ultrathin (4-7 nm) hematite nanosheets using copper oxide nanosheets as a hard template and pro...

Journal: :Nano letters 2011
Peilin Liao Maytal Caspary Toroker Emily A Carter

Hematite (α-Fe(2)O(3)) is a promising candidate for photoelectrochemical splitting of water. However, its intrinsically poor conductivity is a major drawback. Doping hematite to make it either p-type or n-type enhances its measured conductivity. We use quantum mechanics to understand how titanium, zirconium, silicon, or germanium n-type doping affects the electron transport mechanism in hematit...

2013
Jae Young Kim Ganesan Magesh Duck Hyun Youn Ji-Wook Jang Jun Kubota Kazunari Domen Jae Sung Lee

A hematite photoanode showing a stable, record-breaking performance of 4.32 mA/cm² photoelectrochemical water oxidation current at 1.23 V vs. RHE under simulated 1-sun (100 mW/cm²) irradiation is reported. This photocurrent corresponds to ca. 34% of the maximum theoretical limit expected for hematite with a band gap of 2.1 V. The photoanode produced stoichiometric hydrogen and oxygen gases in a...

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