TiO2(B)/anatase heterostructure nanofibers decorated with anatase nanoparticles as efficient photocatalysts for methanol oxidation

Atomic-Scale Investigation on the Evolution of Tio2-Anatase Prepared by a Sonochemical Route and Treated with NaOH

To date, the formation mechanisms of TiO2, as well as its heterostructures, have not been clarified. Moreover, detailed research on the transition from a tetragonal anatase phase to the monoclinic phase of the TiO2(B) phase and their interface structure has been quite limited until now. In the present study, we report on the sonochemical synthesis of TiO2-anatase with a crystallite size of 5.2 ± 1.5 nm under different NaOH concentrations via the hydrothermal method. The use of alkaline solution and the effect of the temperature and reaction time on the formation and structural properties of TiO2-anatase nanopowders were studied. The effects of NaOH concentration on the formation and transformation of titanate structures are subject to thermal effects that stem from the redistribution of energy in the system. These mechanisms could be attributed to three phenomena: (1) the self-assembly of nanofibers and nanosheets, (2) the Ostwald ripening process, and (3) the self-development of hollow TiO2 mesostructures.

Plasma Treating Mixed Metal Oxides to Improve Oxidative Performance via Defect Generation

The generation of structural defects in metal oxide catalysts offers a potential pathway to improve performance. Herein, we investigated the effect of thermal hydrogenation and low-temperature plasma treatments on mixed SiO₂/TiO₂ materials. Hydrogenation at 500 °C resulted in the reduction of the material to produce Ti³⁺ in the bulk TiO₂. In contrast, low temperature plasma treatment for 10 or 20 min generated surface Ti³⁺ species via the removal of oxygen on both the neat and hydrogenated material. Assessing the photocatalytic activity of the materials demonstrated a 40–130% increase in the rate of formic acid oxidation after plasma treatment. A strong relationship between the Ti³⁺ content and catalyst activity was established, although a change in the Si–Ti interaction after plasma treating of the neat SiO₂/TiO₂ material was found to limit performance, and suggests that performance is not determined solely by the presence of Ti³⁺.

Sheet-on-belt branched TiO2(B)/rGO powders with enhanced photocatalytic activity

TiO2(B) is usually adopted to construct phase junctions with anatase TiO2 for applications in photocatalysis to facilitate charge separation; its intrinsic photocatalytic activity, especially when in the form of one- or three-dimensional nanostructures, has been rarely reported. In this study, a sheet-on-belt branched TiO2(B) powder was synthesized with the simultaneous incorporation of reduced graphene oxide (rGO). The monophase, hierarchically nanostructured TiO2(B) exhibited a reaction rate constant 1.7 times that of TiO2(B)/rGO and 2.9 times that of pristine TiO2(B) nanobelts when utilized to assist the photodegradation of phenol in water under UV light illumination. The enhanced photocatalytic activity can be attributed to the significantly increased surface area and enhanced charge separation.

Ag3PO4@holmium phosphate core@shell composites with enhanced photocatalytic activity

In this study, Ag₃PO₄@holmium phosphate (HP) composite photocatalysts were firstly prepared. The core–shell heterojunction structure of Ag₃PO₄@HP significantly improved the photocatalytic activity of Ag₃PO₄.