We report the synthesis of multiwall carbon nanotubes@metal oxide composites (MWCNT@Sn 1-x Ti x O 2 ) and explore the lithium storage capacity and mechanisms in a broad range of compositions. The composite structures were synthesized by hydrothermal method using SnCl 4 and TiCl 4 as Sn and Ti sources, respectively. Oxide adherence on the carbon surface, as well as an optimum ratio between surface area and porosity, seem to be promoted by Sn content, with MWCNT@Sn 0.75 Ti 0.25 O 2 showing the best performance in terms of Li capacity and structure stability. Cycled in a potential range of 3 to 1 V vs Li/ Li + , the composite shows an insertion mechanism reported for solid solutions with low Sn content, whereas at cut off potential of 0 V vs Li/Li + the alloying mechanism expected for SnO 2 is dominant. Nevertheless, the presence of Ti during the transformation of the solid solution impacts positivily the performance of these electrodes.[a] M. Ramírez-Vargas, Dr. M. S. de la Fuente, Dr.
Photoelectrochemical (PEC) characterization of carbon nanotubes-titania (CNT-TiO2) electrodes sensitized with bismuth sulfide (Bi2S3) is presented as a function of CNT-TiO2 annealing temperature and Bi2S3 deposition time. Arrays of CNT were grown on stainless steel substrates by spray pyrolisis and then functionalized with a thin layer of TiO2. Air annealing at 400 and 550ºC modified the morphology and C/TiO2 ratio in the hybrid materials, from CNT-TiO2 coaxial cables to C-doped TiO2. Both matrices increase the amount of Bi2S3 deposited by chemical bath, but the absorbing layer is mainly located at the outer electrode surface. Best PEC performance is observed in electrodes based in C-doped TiO2, as electrodes based on coaxial cables of CNT-TiO2 show large capacitive currents that interfere with photocurrent generation.
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