The effects of natural organic matter (NOM), ferrozine, and AQDS (anthraquinone-2,6-disulfonate) on the reduction of hematite (alpha-Fe2O3) by Shewanella putrefaciens CN32 were studied. It has been proposed that NOM enhances the reduction of Fe(III) by means of electron shuttling or by Fe(II) complexation. Previously both mechanisms were studied separately using "functional analogues" (AQDS for...

The Thermal Emission Spectrometer (TES) on the Mars Global Surveyor spacecraft has detected deposits of coarse-grained, gray crystalline hematite in Sinus Meridiani, Aram Chaos, and Vallis Marineris. We argue that the key to the origin of gray hematite is that it requires crystallization at temperatures in excess of about 100 ◦C. We discuss thermal crystallization (1) as diagenesis at a depth o...

To investigate the influence of the Morin transition on the photoelectrochemical (PEC) activity of hematite, electronic properties in different magnetic phases were studied on the basis of the first-principles calculations within the GGA+U approximation. The results show that the effective electron mass in the (0001) plane changes remarkably due to the spin−flop transition, while the effective ...

-Terra rossa samples were taken from the B horizons of soil profiles and from cracks within limestone in Italy. The average annual temperature (AAT) of the sites ranged from 8.4 to 20.3~ and the average annual precipitation (AAP) from 511 to 3113 mm, with either a 5-6 month water deficit or a large water surplus. Goethite and hematite were identified in all the samples. Under a moist (> 1700 mm...

Augmenting the donor density and nanostructure engineering are the crucial points to improve solar water oxidation performance of hematite (α-Fe2O3). This work addresses the sluggish water oxidation reaction associated with hematite photoanode by tweaking its internal porosity. The porous hematite photoanodes are fabricated by a novel synthetic strategy via pulse reverse electrodeposition (PRED...

A facile and economic route has been presented for mass production of micro/nanostructured hematite microcrystals based on the wet chemical controllable method. The as-prepared samples were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV-Vis absorption spectroscopy. The results showed that the product was mesoporous α -Fe2O3 and near...

The application of hematite in lithium-ion batteries (LIBs) has been severely limited because of its poor cycling stability and rate performance. To solve this problem, hematite nanoparticles with oxygen vacancies have been rationally designed by a facile sol-gel method and a sequential carbon-thermic reduction process. Thanks to the existence of oxygen vacancies, the electrochemical performanc...

Hematite is a promising and extensively investigated material for various photoelectrochemical (PEC) processes for energy conversion and storage, in particular for oxidation reactions. Thermal treatments during synthesis of hematite are found to affect the performance of hematite electrodes considerably. Herein, we present hematite thin films fabricated via one-step oxidation of Fe by rapid the...

We examined the reduction of nitrobenzene by Shewanella putrefaciens CN32 in the presence of natural organic matter (NOM) and hematite. Bioreduction experiments were conducted with combinations and varied concentrations of nitrobenzene, soil humic acid, Georgetown NOM, hematite, and CN32. Abiotic experiments were conducted to quantify nitrobenzene reduction by biogenic Fe(II) and by bioreduced ...

The gray crystalline hematite at Meridiani Planum first discovered by the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES) instrument occurs as spherules that have been interpreted as concretions. Analysis of the TES and mini-TES spectra shows that no 390 cm−1 feature is present in the characteristic martian hematite spectrum. Here, we incorporate the mid-IR optical constants of hem...