Photochemical deposition of Co and Ni based oxygen evolution catalysts on hematite nanorods cathodically shifted the onset potential of photocurrent near to the flat band potential of hematite. A 9.5 fold enhancement in the photocurrent density at 0.86 V vs. RHE compared to the parent hematite photoanode was observed with the Ni-Bi/Fe(2)O(3) photoanode.

Introduction. The Thermal Emission Spectrometer (TES) instrument aboard Mars Global Surveyor discovered several isolated deposits of gray, crystalline hematite in Sinus Meridiani, Aram Chaos, and Valles Marineris. A variety of formation mechanisms has been proposed for the martian hematite deposits [1-5], including aqueous and nonaqueous processes. Comparison of the average Sinus Meridiani hema...

Nuclear magnetic resonance (NMR) relaxation-time measurements can provide critical information about the physiochemical properties of water-saturated media and are used often to characterize geologic materials. In unconsolidated sediments, the link between measured relaxation times and pore-scale properties can be complicated when diffusing water molecules couple the relaxation response of hete...

Iron (oxyhydr)oxides are sensitive indicators of pH, Eh, temperature, microbial activity, and climate conditions in the Critical Zone. The most ubiquitous environmentally significant iron oxides soils two-line ferrihydrite, goethite, hematite. Here we present a comprehensive study transformation ferrihydrite to hematite goethite over wide range temperature (25–170 °C) initial pH (2−13) through ...

We used X-ray diffraction (XRD), scanning force microscopy (SFM), transmission electron microscopy (TEM), and color to investigate the effect of phosphate on the crystallization rate, nature, and morphology of iron oxides prepared from ferrihydrite in the laboratory. Synthesis was performed at two temperatures (323 and 373 K) and two pH values (9 and 12) from ferric nitrate, for P/Fe atomic rat...

Hematite (α-Fe2O3) nanoparticles were synthesized by the solid transformation of ferrous hydroxide and ferrihydrite in hydrothermal condition. The as-prepared α-Fe2O3 nanoparticles were characterized by UV-vis, PL, XRD, Raman, TEM, AFM, FESEM, and EDX analysis. The experimental results indicated the formation of uniform hematite nanoparticles with an average size of 45 nm and perfect crystallin...

The impact of zinc on the reductive dissolution of hematite by the dissimilatory metal-reducing bacterium Shewanella putrefaciens CN32 was studied in batch culture mode. Experiments were conducted with hematite (2.0 g L 1) in 10 mM PIPES (pH 6.8) and H2 as the electron donor under nongrowth conditions (108 cell mL 1), spiked with zinc (0 to 0.23 mM), and incubated for 5 days. Experiments were a...

The rate of reaction of hematite with quinones and the quinone moieties of larger molecules may be an important factor in limiting the rate of reductive dissolution of hematite, especially by iron-reducing bacteria. It is possible that the rate of reductive dissolution of hematite in the presence of excess hydroquinone at pH 2.5 may be limited by the electron-transfer rate. Here, a reductive di...