Slightly hydrogenated white TiO ₂ nanoparticles show enhanced photocatalytic performance due to their increased surface defects, while gray or black H-TiO ₂ nanoparticles display much worse catalytic performances due to the formation of bulk defects.

Elemental, isotopic, and mineral compositions as well as rock textures were examined in samples from Popocatépetl volcano and immediately surrounding monogenetic scoria cones of the Sierra Chichinautzin Volcanic Field, central Mexico. Magma generation is strongly linked to the active subduction regime to the south. Rocks range in composition from basalt to dacite, but Popocatépetl samples are generally more evolved and have mineral compositions and textures consistent with more complicated, multi-stage evolutionary processes. High-Mg calc-alkaline and more alkaline primitive magmas are present in the monogenetic cones. Systematic variations in major and trace element compositions within the monogenetic suite can mostly be explained by polybaric fractional crystallization processes in small and short-lived magmatic systems. In contrast, Popocatépetl stratovolcano has produced homogeneous magma compositions from a shallow, long-lived magma chamber that is periodically replenished by primitive basaltic magmas. The current eruption (1994–present) has produced silicic dome lavas and pumice clasts that display mingling of an evolved dacitic component with an olivine-bearing mafic component. The longevity of the magma chamber hosted in Cretaceous limestones has fostered interaction with these rocks as evidenced by the chemical and isotopic compositions of the different eruptive products, contact-metamorphosed xenoliths, and fumarolic gases. Popocatépetl volcanic products display a considerable range of ⁸⁷Sr/⁸⁶Sr (0·70397–0·70463) and ε_Nd (+6·2 to +3·0) whereas Pb isotope ratios are relatively homogeneous (²⁰⁶Pb/²⁰⁴Pb 18·61–18·70; ²⁰⁷Pb/²⁰⁴Pb 15·56–15·60).

Anatase TiO₂ is considered as one of the promising anode materials for lithium ion batteries (LIBs) because of its nontoxicity, safety, and excellent capacity retention. However, the poor rate capability of TiO₂ electrodes, caused by the low electrical conductivity and lithium diffusion coefficient, strongly hinders its practical application in high power LIBs. Herein, we report on the fast lithium storage performance of hydrogenated anatase TiO₂ nanoparticles (H-TiO₂) prepared by a H₂ plasma treatment. The scan-rate dependence of the cyclic voltammetry (CV) analysis reveals that the improved rate capability of H-TiO₂ results from the enhanced contribution of pseudocapacitive lithium storage on the particle surface. Combined with the structural properties of H-TiO₂, it is suggested that the disordered surface layers and Ti³⁺ species of H-TiO₂ play an important role in the improvement of pseudocapacitive lithium storage. The results help to understand the fast lithium storage performance of H-TiO₂ and might pave the way for further studies of other hydrogenated metal oxide electrodes for high power LIBs.