Construction of hollow waxberry-like rutile-/anatase-TiO2/SnO2 towards enhanced photocatalysis

Visible-Light-Responsive Photoreversible Multi-Color Switching for Rewritable Light-Printing and Information Display

Photoreversible color switching systems (PCSSs) exhibiting multi-color responses to visible light are favored for sustainable societal development over those relying on ultraviolet light due to safer operation and better penetration depth. Here, a PCSS capable of multi-color switching responsive to visible light based on highly photoreductive rutile-phase Sn-doped TiO2-x nanoparticles is reported. The Sn-doping significantly red-shifts the absorption band of the nanoparticles to the visible region, improving charge separation and transfer efficiencies and introducing Ti3+ species and oxygen vacancies as internal sacrificial electron donors for scavenging photogenerated holes. The resulting Sn-doped TiO2-x nanoparticles feature exceptional photoreduction ability and activity, thereby enabling photoreversible color switching of various redox dyes operational under visible light illumination. Furthermore, multi-color switching can be achieved via the color overlay effect by combining different redox dyes in one system, opening the door to many advanced applications, as demonstrated in their successful uses for developing visible-light-driven rewritable multi-color light-printing systems and visual information displays.

Preparation, Characterization of ZnTiO3/ZnO Composite Materials and Their Photocatalytic Performance

With zinc acetate and butyl titanate as raw materials, pure ZnO and ZnTiO₃/ZnO composite photocatalysts were synthesized by a sol-gel method and calcined at 550 °C. The crystal structure, morphology, surface area, optical property, and element valence states of samples were characterized and the photocatalytic activity of the prepared photocatalysts were assessed by the degradation of rhodamine B. Results show that the crystal structure of ZnO is a hexagonal wurtzite phase with a band gap of 3.20 eV. When the Zn/Ti molar ratio reaches 0.2, ZnTiO₃ phase appears and ZnTiO₃/ZnO composite forms, which advances the transfer of photogenerated charges. ZnTiO₃/ZnO (Ti/Zn = 0.2) exhibits the highest photocatalytic activity, and the degradation degree of RhB reaches 99% after 60 min, which is higher than that of pure ZnO (90%). An exorbitant Ti/Zn molar ratio will reduce the crystallinity and form more amorphous components, which is not conducive to photocatalytic performance. Therefore, when the Ti/Zn molar ratio exceeds 0.2, the photocatalytic activities of ZnTiO₃/ZnO composites decrease.

Ag Decoration and SnO2 Coupling Modified Anatase/Rutile Mixed Crystal TiO2 Composite Photocatalyst for Enhancement of Photocatalytic Degradation towards Tetracycline Hydrochloride

The anatase/rutile mixed crystal TiO2 was prepared and modified with Ag decoration and SnO2 coupling to construct a Ag@SnO2/anatase/rutile composite photocatalytic material. The crystal structure, morphology, element valence, optical properties and surface area were characterized, and the effects of Ag decoration and SnO2 coupling on the structure and photocatalytic properties of TiO2 were studied. Ag decoration and SnO2 coupling are beneficial to reduce the recombination of photogenerated electrons and holes. When the two modification are combined, a synergistic effect is produced in suppressing the photogenerated charge recombination, making Ag@SnO2/TiO2 exhibits the highest quantum utilization. After 30 min of illumination, the degradation degree of tetracycline hydrochloride (TC) by pure TiO2 increased from 63.3% to 83.1% with Ag@SnO2/TiO2.

Hollow porous BiOCl microspheres assembled with single layer of nanocrystals: spray solution combustion synthesis and the enhanced photocatalytic properties

The hollow porous microspheres assembled with BiOCl nanocrystals were successfully synthesized via a facile spray solution combustion synthesis method. The microstructure, morphology, absorbance, optical properties of the samples were investigated in detail. The results show that hollow porous BiOCl microspheres have narrow band gaps (2.66-2.71 eV), and the degradation rate of rhodamine B (RhB) can reach 98% under visible light irradiation for 60 min. Furthermore, the mechanism of the photocatalytic degradation of RhB was proposed through the experiment of trapping active species. This excellent photocatalytic property can be ascribed to the larger specific surface area and the special microstructure.

Optimizing the synthesis of SnO2/TiO2/RGO nanocomposites with excellent visible light photocatalytic and antibacterial activities

Multifunctional SnO₂/TiO₂/RGO nanocomposites with enhanced photocatalytic degradation and antibacterial activity have been successfully synthesized by a facile one-pot environmentally friendly green hydrothermal route using titanium tetrabutoxide (TBOT), Na₂SnO₃ and graphene oxide (GO) without reducing agents and any structure-directing agents. The results demonstrate that the reaction pH conditions play important roles in the control of the crystallographic phases of TiO₂ and SnO₂. In addition, the visible-light-active photocatalytic and antibacterial activities of the synthesized composites were measured for the degradation of rhodamine B (RhB) and the growth inhibition of the Gram-negative bacteria Escherichia coli (E. coli), which are strongly affected by the SnO₂ loading content, the crystal structure of TiO₂ and the appropriate addition of graphene. The superior photocatalytic and antibacterial activities of the nanocomposites were attributed to their great optical adsorption capability and excellent charge separation and transfer efficiency. This study may provide new insights into the fabrication of efficient visible-light-active SnO₂/TiO₂/RGO nanocomposites and expand their applications in the environmental remediation and water disinfection fields.