Cerium oxide nanoparticles (CONPs), widely used in catalytic applications owing to their robust redox reaction, are now being considered in therapeutic applications based on their enzyme mimetic properties such as catalase and super oxide dismutase (SOD) mimetic activities. In therapeutic applications, the emerging demand for CONPs with low cytotoxicity, high cost efficiency, and high enzyme mimetic capability necessitates the exploration of alternative synthesis and effective material design. This study presents a room temperature aqueous synthesis for low-cost production of shape-selective CONPs without potentially harmful organic substances, and additionally, investigates cell viability and catalase and SOD mimetic activities. This synthesis, at room temperature, produced CONPs with particular planes: {111}/{100} nanopolyhedra, {100} nano/submicron cubes, and {111}/{100} nanorods that grew in [110] longitudinal direction. Enzymatic activity assays indicated that nanopolyhedra with a high concentration of Ce4+ ions promoted catalase mimetic activity, while nanocubes and nanorods with high Ce3+ ion concentrations enhanced SOD mimetic activity. This is the first study indicating that shape and facet configuration design of CONPs, coupled with the retention of dominant, specific Ce valence states, potentiates enzyme mimetic activities. These findings may be utilized for CONP design aimed at enhancing enzyme mimetic activities in therapeutic applications.
The human life faces serious energy shortage and environmental pollution problems, therefore developing a facile and environmental friendly strategy for synthesizing nanoparticles (NPs) with improved photocatalytic activity could pave the way for different applications. In the present study, one-pot/in-situ fluorine-free synthesis process has been examined toward the solvothermal production of anatase TiO2 nanoparticles with exposed facet orientation. This is an aim to achieve the excellent photocatalytic/photoelectrocatalytic performance. Most importantly addressing the global energy shortage, the synthesized TiO2 NPs represent superior performance in photoelectrocatalytic water splitting toward hydrogen production. The overpotential required to drive the hydrogen evolution reaction was −391, −346 and −283 mV vs. Ag/AgCl for P25, cubic and truncated octahedral NPs, respectively. Additionally, TiO2 NPs with exposed facets represent excellent photocatalytic performance toward environmental purification. As synthesized nanoparticles was examined via photocatalytic degradation of Acid Blue 5 and photocatalytic removal of NO gas. The enhanced photocatalytic and photoelectrocatalytic performance are associated to the effect of exposed facet orientation of final nanoparticles. 相似文献
Efficient removal of tetracycline (TC) under visible-light irradiation over TiO2-based photocatalysts remains a challenge based on the fact that the reported photocatalytic systems still suffer from weak visible-light absorption and/or inefficient charge separation. Herein, we constructed {101} and {001} facets co-exposed TiO2 hollow sphere (001-HT) via a gentle NaF treatment, in which the hollow mesoporous feature can trap incident light for a long time to improve photons efficiently. Meanwhile, the as-formed facet heterojunction significantly facilitates the charge separation. As a result, the 001-HT exhibits a high removal rate (~90.1%) of TC under visible-light irradiation, beyond the values of many reported TiO2-based photocatalysts. Most importantly, we further expound the ligand-to-metal charge transfer mechanism towards TiO2-assisted degradation of TC under visible-light irradiation, which effectively clarifies the confusion about the origin of pure TiO2 visible-light activity towards TC degradation because both TiO2 and TC do not exhibit any visible-light catalytic activity. Therefore, this work provides a new insight in revealing the mechanism of visible-light-mediated TC degradation over pure TiO2 photocatalyst. 相似文献