Augustus Merwin

Application of ZnxCd1−xSe-sensitized TiO2 nanotube arrays as photoanodes for solar cells

This study reports the synthesis of ZnxCd1−xSe quantum dot-sensitized titania nanotube array photoelectrodes using a successive ionic layer adsorption and reaction technique and evaluates the photoelectrochemical performance as anodes. The effect of altering the number of sensitization cycles and annealing temperature on optical and photoelectrochemical properties of prepared photoanodes was studied. Surface morphology of the sensitized tubes was analyzed by scanning electron microscopy, while the phase composition was determined using X-ray diffraction and X-ray photoelectron spectroscopy techniques. Spectral response measurements indicated that TiO2 nanotube arrays coupled with ZnxCd1−xSe quantum dots synthesized in 7 cycles of deposition and annealed at 300 °C for 1 h under N2 exhibited excellent photoelectrochemical properties. The notably high photovoltaic characteristics demonstrate the potential of the ZnxCd1−xSe/TiO2 heterostructure as an efficient photoanode.

Presence of Li Clusters in Molten LiCl-Li

Molten mixtures of lithium chloride and metallic lithium are of significant interest in various metal oxide reduction processes. These solutions have been reported to exhibit seemingly anomalous physical characteristics that lack a comprehensive explanation. In the current work, the physical chemistry of molten solutions of lithium chloride and metallic lithium, with and without lithium oxide, was investigated using in situ Raman spectroscopy. The Raman spectra obtained from these solutions were in agreement with the previously reported spectrum of the lithium cluster, Li8. This observation is indicative of a nanofluid type colloidal suspension of Li8 in a molten salt matrix. It is suggested that the formation and suspension of lithium clusters in lithium chloride is the cause of various phenomena exhibited by these solutions that were previously unexplainable.

Corrosion of INCONEL Alloy 625 in Molten LiCl-Li2O-Li

Abstract INCONEL alloy 625® (I625) was exposed to molten LiCl-Li2O-Li to evaluate the material reliability for applications involving the electrolytic reduction of uranium oxide. Samples of I625 were exposed to solutions of LiCl with 1 and 2 wt% Li2O, containing either 0, 0.5, or 1 wt% metallic lithium for 20 h at 650°C. Additional experiments exposed samples to LiCl saturated with Li2O to investigate the mechanism of interaction between materials and the melt. Postexposure sample surface morphology and chemistry were studied using scanning electron microscopy and X-ray photoelectron spectroscopy. Additionally, inductively coupled plasma–optical emission spectroscopy was used to analyze the melt to determine the alloy constituents that leached out of the coupon during the exposure. The inclusion of 0.5 wt% metallic lithium in the molten solution was found to increase the stability of chromium-rich surface films and suppress the dissolution rate of alloying elements, compared to melts of LiCl-Li2O containing no metallic Li. Alternatively, samples exposed to solutions containing 1 wt% metallic lithium did not form surface films and demonstrated evidence of chromium depletion. The degradation of materials exposed to solutions containing 1 wt% metallic lithium was observed to be different from samples exposed to solutions saturated with lithium oxide, demonstrating a chemical effect other than, or in addition to, salt basicity.