Hydrogenation largely improves the microwave absorbing efficiency of BaTiO3 nanoparticles.

The influence of the amount of hydrogen fluoride (HF) on product formation from the hydrothermal reaction of titanium butoxide and concentrated HF is investigated. Low HF contents lead to a preference for the formation of small TiO2 nanoparticles, medium HF contents lead to a preference for TiO2 nanosheets, and high HF contents lead to a preference for large TiOF2 particles. Meanwhile, TiO2 nanosheets display higher activity in photocatalytic hydrogen generation than that of smaller TiO2 nanoparticles; this demonstrates the higher photocatalytic activity of (001) facets over others. The synergistic effect between TiO2 nanosheets and TiOF2 particles could improve the performance of TiO2 nanosheets owing to possible charge separation over their interface, although TiOF2 particles themselves barely show any activity.

Hydrogenation has been demonstrated in successfully modifying the structural, electronic and optical properties of TiO2 nanoparticles, along with its improved photocatalytic performance. In our original study, hydrogenated black TiO2 nanoparticles were obtained by heating white crystalline TiO2 nanocrystals in a high-pressure pure hydrogen environment. This treatment induced a thin disordered layer near the surface, surrounding a crystalline core. This layer was believed to introduce extra electronic states in the bandgap and the longwave length absorption. The hydrogenated black TiO2 nanoparticles showed excellent and stable photocatalytic performance in photocatalytic hydrogen generation and pollutant (methylene blue and phenol) decomposition. The enhancement was partially attributed to the efficient electron and hole trapping in the disordered layer to allow better charge separation on the surface. Hydrogenated black TiO2 nanoparticles have also been developed with other fabrication approaches as well, such as electrochemical hydrogenation and hydrogen plasma. So far, hydrogenated TiO2 nanocrystals have

The rapid depletion of the fossil fuel reserves, and the increase of green-house gas emissions and other environmental pollutants, bring up an urgent need for the development of clean energy and sustainable environmental solutions. The ability to use sunlight to produce fuels such as H-2 from abundant, nontoxic resources, and to decompose environmental pollutants with benign photocatalysts, would revolutionize our civilization. TiO2 has attracted substantial interest due to its activity for generating hydrogen from water under ultraviolet (UV) light irradiation. The discovery of (001) facet control with the fluoride additive in the reactants has triggered intensive studies for model photocatalysis. Here, we found that small TiO2 nanoparticles were formed at the very beginning stage of the reaction, then were transformed into large TiOF2 crystals, and finally turned into (001)-faceted TiO2 nanosheets. TiOF2 acted as a metastable intermediate medium in the transformation from TiO2 nanoparticles into (001)-faceted TiO2 nanosheets. The (001) face showed higher activity for the photocatalytic generation of hydrogen and the photodecomposition of methylene blue and rhodamine B. The synergic effect between TiOF2 and TiO2 nanosheets or nanoparticles further improved the photocatalytic activities. This study provides us with a promising solution for solving the energy and environment problems

We report here the photocatalytic hydrogen generation from pure (deionized) water under simulated solar light with silicon carbide (SiC) nanoparticles, without the assistance of sacrificial reagents or precious metal co-catalysts. We have studied the pH effects of the addition of methanol and the loading of a Pt co-catalyst on the photocatalytic hydrogen generation efficiency of SiC nanoparticles. We have found that SiC nanoparticles display the best photocatalytic hydrogen generation efficiency in pure water. SiC nanoparticles show activity in both ultraviolet (UV) and visible-light regions. The addition of methanol in water or loading of Pt nanoparticles on the surface lowers their activity. Thus, SiC nanoparticles may serve as an ideal model photocatalyst for future studies in generating hydrogen from pure water.

Following our previous findings on hydrogenated black TiO2 nanoparticles, here, we would like to present our exciting findings on hydrogenated black ZnO nanoparticles, which have displayed long-wavelength absorption and excellent photocatalytic performance. This further demonstrates that hydrogenation is a powerful tool to enhance the optical and photocatalytic performance of nanomaterials.

Titanium dioxide (TiO2) is important for both fundamental studies and technical applications. Here we present laser power dependence Raman spectroscopic studies of rutile TiO2 to reveal the response of various Raman-active lattice vibrations. Apparently, different vibrational modes display distinctive and reversible trends with the change of laser power. The Ti-O bond strength involved with different vibrational modes changes differently as the laser power changes. The relaxation time becomes shorter as the laser power increases. The changes of the bond strength and relaxation time can be related to the local temperature change with the laser power. The observed different behaviors in the vibrational modes suggest that the lattice movements along various directions face different temperature environments under the same light irradiation.