Huiping Zhao

Size-tunable fabrication of multifunctional Bi2O3 porous nanospheres for photocatalysis, bacteria inactivation and template-synthesis

Multifunctional Bi2O3 porous nanospheres (PNs) with tunable size have been successfully synthesized via a facile solvothermal method. The obtained Bi2O3 porous nanospheres demonstrate outstanding performance in visible-light-driven photocatalysis for Cr(VI) and organic dye removal, inactivation of Gram-negative and Gram-positive bacteria, as well as template-synthesis for fabrication of bismuth-related hollow nanostructures.

Modification with Metallic Bismuth as Efficient Strategy for the Promotion of Photocatalysis: The Case of Bismuth Phosphate

A BiPO4 nanostructure modified with Bi nanoparticles rich in oxygen vacancies in the surface and subsurface was prepared through a one-pot solvothermal treatment utilizing the weak reductive ability of ethylene glycol (EG). The presence of Bi nanocrystals and oxygen vacancies is beneficial for the separation and consumption of photogenerated electrons and holes where Bi nanocrystals act as active sites for the formation of (.) OH and oxygen vacancies are active sites for (.) O2 (-) formation. The enhanced photocatalytic activity is ascribed to the synergistic effect of Bi nanocrystals and surface oxygen vacancies.

Hydrothermal synthesis of porous α-Fe2O3 nanostructures for highly efficient Cr(VI) removal

Porous α-Fe2O3 nanostructures with different morphologies, such as rod-like, sphere-like and cube-like nanostructures, were successfully synthesized via a facile hydrothermal method. The obtained products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and nitrogen adsorption. It was found that iron precursors played a crucial role in the formation of porous α-Fe2O3 nanostructures. The porous α-Fe2O3 nanorods possessed largest BET surface area and ideal pore distribution, as well as exhibited excellent Cr(VI) removal capacity and a fast adsorption rate in a wide pH range. Moreover, porous α-Fe2O3 nanorods also showed excellent adsorptive ability for organic dyes.

Mannitol-assisted solvothermal synthesis of BiOCl hierarchical nanostructures and their mixed organic dye adsorption capacities

Three-dimensional (3D) hierarchical BiOCl nanostructures constructed by interconnected two-dimensional (2D) nanoplates have been successfully synthesized via a facile solvothermal process with the assistance of mannitol. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption. In the synthesis, mannitol acted both as a capping agent and a cohesive agent to mediate the formation of a hierarchical structure. A possible growth process involving crystal anisotropic growth habit and assembly process was proposed. The adsorption performance of BiOCl products for mixed organic dye removal was evaluated by using cationic rhodamine B (RhB) and anionic methyl orange (MO) as target substances. The as-prepared hierarchical BiOCl product exhibited excellent adsorption capacity and favorable recycling ability for mixed organic dye removal. This work demonstrated a novel strategy for the design and application of a well-defined complex hierarchical nanostructure.

Rhodamine B-sensitized BiOCl hierarchical nanostructure for methyl orange photodegradation

Loose-packed flower-like BiOCl hierarchical nanostructures (HNs) assembled by thin nanosheets were successfully synthesized via a facile solvothermal method. Based on the matchability analysis of band structure of BiOCl and the molecular orbitals of the dyes, the RhB dye-sensitized heterogeneous BiOCl HNs system was established for MO degradation under visible light irradiation. The mechanism of MO degradation over RhB-sensitized BiOCl was also discussed according to the photocurrent and photoluminescence results. It was found that MO degradation efficiency over RhB-sensitized BiOCl HNs was obviously improved due to the generation of superoxide radicals (˙O2−) through the reduction of surface-adsorbed O2 molecules by the injected electrons on the conduction band of BiOCl HNs from the excited RhB molecules. This work may provide insight on better understanding the organic dye photodegradation process in RhB dye-sensitized BiOCl heterogeneous systems and explore a dye-sensitized semiconductor photocatalyst strategy for environmental remediation.

Fabrication uniform hollow Bi2S3 nanospheres via Kirkendall effect for photocatalytic reduction of Cr(VI) in electroplating industry wastewater

Hazardous hexavalent chromium removal from wastewater is an urgent issue in industry environmental pollution. In this work, hollow Bi2S3 nanospheres have been successfully synthesized from unique Bi2O3 porous nanospheres via Kirkendall effect through hydrothermal process. It was found that the sulfur source and the initial Bi2O3 templates played key roles in the formation of the uniform morphologies and structures through an anion exchange process. Compared with other Bi2S3 samples, the synthesized hollow Bi2S3 nanospheres exhibited much enhanced photocatalytic ability for Cr(VI) photoreduction. XPS analysis demonstrated that Cr(VI) was reduced to less harmful Cr(III) species over hollow Bi2S3 nanospheres under visible-light irradiation. More importantly, the hollow Bi2S3 nanospheres remained high efficiency and good stability in the recycling Cr(VI) photoreduction, and exhibited remarkable Cr(VI) removal ability in actual electroplating industry wastewater treatment.

Generation of defect clusters for 1O2 production for molecular oxygen activation in photocatalysis

Defect engineering on a semiconductor surface can provide coordinatively unsaturated sites for molecular oxygen activation in photocatalysis. In this work, we demonstrated that the vacancy type was key to modulate the molecular oxygen activation process on BiOBr nanosheets. By regulating the reaction time, an oxygen vacancy , a double atom defect cluster and triple atom clusters were accordingly generated on the surface, subsurface and bulk of BiOBr. More importantly, the newly-discovered defect cluster was highly related to the singlet oxygen (1O2) production ability of BiOBr. Meanwhile, the excellent photocatalytic selective oxidation reactions were successfully realized over BiOBr with the defect cluster. In addition, time-dependent defect cluster generation and the associated molecular oxygen activation were discussed.