Rhodium sulfide/carbon nanocomposites were synthesized via a one-step alcohol-thermal method at 400 C from Rh 6 (CO) 16 and elemental S. Characterizations by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy revealed that the products were composed of amorphous carbon with spherical morphology and numerous highly crystallized Rh 2 S 3 /Rh 17 S 15 nanocrystals, presented as uniform size composite nanospheres of 45-90 nm diameter. The crystallographic composition of rhodium sulfide in those composites depended on the initial S/Rh molar ratio and utilized solvent. Such hybrid nanomaterials displayed good dispersion of the rhodium sulfide nanoparticles, high surface area and extraordinary thermal/chemical resistance, making them attractive materials for electrocatalytic application of HCl electrolysis. Cyclic voltammetry and rotating disk electrode measurements were employed to evaluate the catalytic performance for oxygen reduction reaction in HCl electrolysis. It was illustrated that all rhodium sulfide/carbon nanocomposites were active towards oxygen reduction reaction. Especially, the catalyst synthesized in ethanol containing Rh 17 S 15 phase outperformed commercial Pt/C in stability. Recently, our group reported hydrothermal and xylenethermal synthesis of rhodium suldes. 24,25 Both methods led to well-crystallized Rh 2 S 3 or Rh 17 S 15 phase, depending on the initial S/Rh molar ratio in the raw materials. The solvothermal reaction conducted in xylene gives rise to products with higher
Theoretical study of water saturation in oil-water fluid flow area is meaningful to the high, stabilized production and the improvement of ultimate recovery. At present, there is no theoretical description of water saturation in the oil and water seepage process. Combining relational expression between relative permeability and water saturation with the fractional flow equation produces an expression of water cut changed by water saturation; Introducing Taylor expansion and Vieta's theorem to the differentiation of water cut gives a theoretical expression of water saturation in oilwater fluid flow area; Possibility of continuity of the water saturation is also discussed. Applying this formula to certain sandstone reservoir in China achieves good results: In oil-water seepage process, water saturation is continuous in certain interval and the values of it are double in another interval; the oil recovery can be re-calculated and improved with this new equation. This new water saturation equation lays a base for the study of residual oil mobility and enhanced oil recovery.
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