Effect of Reynolds number and lithium cation insertion on titanium anodization

This work studies the influence of using hydrodynamic conditions (Reynolds number, Re = 0 to Re = 600) during Ti anodization and Li+ intercalation on anatase TiO2 nanotubes. The synthesized photocatalysts were characterized by using Field Emission Scanning Electron Microscope (FE-SEM), Raman Confocal Laser Microscopy, Electrochemical Impedance Spectroscopy (EIS), Mott-Schottky analysis (M-S), photoelectrochemical hydrogen production and resistance to photocorrosion tests. The obtained results showed that the conductivity of the NTs increases with Li+ intercalation and Re. The latter is due to the fact that the hydrodynamic conditions eliminate part of the initiation layer formed over the tube-tops, which is related to an increase of the photocurrent in the photoelectrochemical water splitting. Besides, the photogenerated electron-hole pairs are facilitated by Li+ intercalation. Finally, this work confirms that there is a synergistic effect between Re and Li+ intercalation

Past ice flow in Wahlenbergfjorden and its implications for late Quaternary ice sheet dynamics in northeastern Svalbard

Wahlenbergfjorden is a fjord situated in the western part of Nordaustlandet in northern Svalbard. It leads into the 400 m deep Hinlopen Strait located between Nordaustlandet and Spitsbergen. High-resolution multibeam bathymetric and sub-bottom data, as well as sediment cores are used to study the past extent and dynamics of glaciers in Wahlenbergfjorden and western Nordaustlandet. The submarine landform assemblage in Wahlenbergfjorden consists of landforms characteristic of subglacial, ice marginal and proglacial conditions. Glacial lineations indicate that Wahlenbergfjorden was occupied by streaming ice during the LGM and most likely acted as an ice stream onset zone. Westward ice flow in the fjord merged with the ice stream in Hinlopen Strait. Absence of ice recessional landforms in outer Wahlenbergfjorden suggests relatively fast deglaciation, possibly by flotation of the glacier front in the deeper parts of the fjord. The inner part of Wahlenbergfjorden and Palanderbukta are characterized by De Geer moraines, indicating episodic retreat of a grounded glacier front. In Palanderbukta, longer still stands of the glacier terminus resulted in the formation of larger terminal moraine ridges. The inner part of Wahlenbergfjorden was deglaciated prior to 11.3 ± 55 Cal. ka BP. The submarine landform assemblages in front of Bodleybreen, Etonbreen, Idunbreen, Frazerbreen and Aldousbreen confirm that these glaciers have surged at least once during the Holocene

Improved photocatalytic efficiency of TiO2 open nanotube arrays: a view by XAS

[[abstract]]Highly ordered TiO2 nanotube (TiNT) arrays were prepared on Ti foil. The interfacial caps between nanotube bottom and Ti foil were gradually removed by oxalic acid. The removal of caps in TiNT is known to enhance its light-harvesting capability, increase the carrier transfer, and cause effective dissociation of electron-hole pairs. The electronic and local atomic structures of TiNT at different oxalicacid immersion time were investigated by XAS. Notably, the reported enhanced light harvesting and electron collecting efficiencies in both-end open TiNT, could be strongly correlated with charge redistribution in Ti 3d orbital and structural defect. An increase in Ti 3d unoccupied states due to increase in Ti4+/Ti3+ ratio followed by a decrease in oxygen vacancy at the closed-end bottom caps after 16 h oxalicacid immersion might be one of the reasons for enhanced efficiency of both end open TiNT against one end open tube. EXAFS analysis revealed an increase in CN number and Ti–O bond length, which results in the formation of disordered TiO6 Oh symmetry that would possibly enhance the lattice phonons and eventually the efficiency of TiNT. This is one of the fundamental reasons for the improved photocatalytic properties for both-end open TiNT against closed bottom-end nanotubes.[[notice]]補正完