After several high-profile incidents that raised concerns about the hazards posed by lithium ion batteries, research has accelerated in the development of safer electrodes and electrolytes. One anode material, titanium dioxide (TiO2), offers a distinct safety advantage in comparison to commercialized graphite anodes, since TiO2 has a higher potential for lithium intercalation. In this article, we present two routes for the facile, robust synthesis of nanostructured TiO2/carbon composites for use as lithium ion battery anodes. These materials are made using a combination of colloidal crystal templating and surfactant templating, leading to the first report of a three-dimensionally ordered macroporous TiO2/C composite with mesoporous walls. Control over the size and location of the TiO2 crystallites in the composite (an often difficult task) has been achieved by changing the chelating agent in the precursor. Adjustment of the pyrolysis temperature has also allowed us to strike a balance between the size of the TiO2 crystallites and the degree of carbonization. Using these pathways to optimize electrochemical performance, the primarily macroporous TiO2/C composites can attain a capacity of 171 mAh/g at a rate of 1 C. Additionally, the carbon in these composites can function as a secondary template for high-surface-area, macroporous TiO2 with disordered mesoporous voids. Combining the advantages of a nanocrystalline framework and significant open porosity, the macroporous TiO2 delivers a stable capacity (>170 mAh/g at a rate of C/2) over 100 cycles.
Molten salt based direct electrochemical de-oxidation methods were investigated for the conversion of ThO2 to Th metal in CaCl2 melts at 900 °C. A Fray-Farthing-Chen (FFC) Cambridge process was performed at a constant cell voltage of 3.1 V wherein a cathode of porous ThO2 pellet and a graphite anode were used. The study also explored the feasibility of electro-calciothermic reduction of ThO2 in CaCl2–0.5 wt.% CaO melt. Electrochemical experiments were carried out for different intervals of time to elucidate the reduction mechanism. The cathode products were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis. No Ca-Th-O intermediate phases were observed during the reduction experiments in either process. This indicates that the reduction might occur in a single step viz. ThO2 to Th. The direct electrochemical reduction of ThO2 in CaCl2 based melts at 900 °C was found to be feasible.
The aim of the present study was to prepare U-7 wt.% Nb alloy by the direct oxide electrochemical reduction method. The alloy was prepared from the mixed oxide precursors namely, UO2 and Nb2O5. When the precursors were sintered in a reducing atmosphere of Ar-8 vol.% H2, Nb2O5 was converted into NbO2. Subsequently, the mixed oxide pellet (UO2-NbO2) was reduced by the lithium metal, electrochemically generated from a molten LiCl-1 wt.% Li2O bath at 700°C. The electro-lithiothermic reduction was performed by constant current electrolysis mode with a mixed oxide pellet as the cathode and platinum as the anode. The reduction pathways of the individual oxides and the mixture were established using cyclic voltammetry and potentiostatic electrolysis techniques. The reduced alloy was characterized by X-ray diffraction and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). These results confirmed the formation of U-Nb alloy. The composition of the alloy was determined by EDS, energy-dispersive X-ray fluorescence and chemical analysis.
Microbial fuel cell (MFC) is an emerging technology which has been immensely investigated for wastewater treatment along with electricity generation. In the present study, the treatment efficiency of MFC was investigated for hydrocarbon containing wastewater by optimizing various parameters of MFC. Mediator‐less MFC (1·2 l) was constructed, and its performance was compared with mediated MFC with Escherichia coli as a biocatalyst. MFC with electrode having biofilm proved to be better compared with MFC inoculated with suspended cells. Analysis of increasing surface area of electrode by increasing their numbers indicated increase in COD reduction from 55 to 75%. Catholyte volume was optimized to be 750 ml. Sodium benzoate (0·721 g l–1) and actual common effluent treatment plant (CETP) wastewater as anolyte produced 0·8 and 0·6 V voltage and 89 and 50% COD reduction, respectively, when a novel consortium of four bacterial strains were used. Twenty MFC systems with the developed consortium when electrically connected in series‐parallel connection were able to generate 2·3 V and 0·5 mA current. This is the first report demonstrating the application of CETP wastewater in the MFC system, which shows potential of the system towards degradation of complex organic components present in industrial wastewater.
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