Improving the Photoelectrochemical Response of TiO2 Nanotubes upon Decoration with Quantum-Sized Anatase Nanowires

TiO2 nanotubes (NTs) have been widely used for a number of applications including solar cells, photo(electro)chromic devices, and photocatalysis. Their quasi-one-dimensional morphology has the advantage of a fast electron transport although they have a relatively reduced interfacial area compared with nanoparticulate films. In this study, vertically oriented, smooth TiO2 NT arrays fabricated by anodization are decorated with ultrathin anatase nanowires (NWs). This facile modification, performed by chemical bath deposition, allows to create an advantageous self-organized structure that exhibits remarkable properties. On one hand, the huge increase in the electroactive interfacial area induces an improvement by 1 order of magnitude in the charge accumulation capacity. On the other hand, the modified NT arrays display larger photocurrents for water and oxalic acid oxidation than bare NTs. Their particular morphology enables a fast transfer of photogenerated holes but also efficient mass and electron transport. The importance of a proper band energy alignment for electron transfer from the NWs to the NTs is evidenced by comparing the behavior of these electrodes with that of NTs modified with rutile NWs. The NT-NW self-organized architecture allows for a precise design and control of the interfacial surface area, providing a material with particularly attractive properties for the applications mentioned above.

The Use of the Relative Interior in Integration with Nonconvex Data

Introducing an appropriate inclusion between approximate minima associated with two nonconvex functions, we derive explicit relations between the closed convex hulls of these functions. The formula we obtain goes beyond the so-called epi-pointed property of functions which is usually concerned with such a topic.

El plano geométrico de Crevillent: un pla urbanístic de sanejament i reforma interior de José Guardiola Picó el 1877

El present article analitza i situa en el context l’expedient urbanístic sobre la reforma interior del nucli urbà de Crevillent que l’ajuntament d’aquesta ciutat intentà dur a terme en l’últim quart del segle xix i que, en part, constitueix el plànol geomètric parcial d’aquesta vila. Es tracta d’un expedient municipal en què se succeeixen les actes del consistori per a la seua tramitació administrativa (entre 1876 i 1878) i en què s’intercala el projecte urbà de reforma interior, que consta de tres documents (memòria i dos planols: geomètric i de perfils), firmats el 12 de gener de 1877 per l’arquitecte José Guardiola y Picó (1836-1909), i que es tanca amb un plànol solt del 9 de gener de 1884 de firma no molt llegible.