Hierarchically Assembled Porous ZnO Nanoparticles:  Synthesis, Surface Energy, and Photocatalytic Activity

Abstract

We show an effective experimental method to prepare hierarchically porous zinc oxide (ZnO) spherical nanoparticles through a self-assembly pathway using surface-modified colloidal ZnO nanocrystallites as the building blocks and P-123 copolymers as the template in aqueous solution. Copolymers are thoroughly removed by Soxhlet extraction with ethanol and calcination at 400 °C. The final products have been characterized by X-ray powder diffraction (XRD) pattern, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and photoluminescence (PL) spectroscopy. On the basis of calorimetric measurements reported separately, the surface enthalpy (γ) of the hydrated porous ZnO is 1.42 ( 0.21 J/m 2 , in good agreement with that of ZnO nanoparticles. The calorimetric results support the presence of self-assembled ZnO nanocrystallites in the nanoporous ZnO. Photocatalytic activitiy of porous ZnO nanoparticles has been tested on the photodegradation of phenol under ambient condition, indicating that porous ZnO nanoparticles show superior activity to TiO 2 nanoparticles (PC-500).

Synthesis of Multi-walled Carbon Nanotubes/ZnO Nanocomposites using Absorbent Cotton

“…XRD results of ZnO show prominent 100, 002 and 101 reflections among which 101 is of highest intensity [19][20][21]. The diameter (D) of the ZnO nanoparticles was calculated using the DebyeScherrer formula D=Kλ/(βcosθ), where K is the Scherrer constant (0.9 in this study), λ is the Xray wave length, β is the peak width at halfmaximum, and θ is the Bragg diffraction angle.…”

The synergistic effect and mechanism of doxorubicin-ZnO nanocomplexes as a multimodal agent integrating diverse anticancer therapeutics

“…14,15 Among them, the ZnO nanomaterials are believed to be biologically safe and noncytotoxic, and to have significant photocatalyzed cell-killing effect in vitro resulting from the formation of ROS, which are believed to be responsible for a cascade of cellular and molecular events relevant to tumor destruction. 6,7,16 As illustrated in Figure 3, when treated with the ZnO nanomaterials, about 95% of the cells survived compared with the control group, suggesting …”

“…The production of free radicals and oxidative stress is also closely involved in the action of Dox and ZnO nanomaterials, in terms of both anticancer and toxic effects. 16,18 Evidence shows that the sensitivity of cells to the apoptotic stimulus is determined by the relative ratio of Bax and Bcl-2, which are the proapoptotic and antiapoptotic members of the Bcl-2 family, ie, the mitochondrial-related death switch. 19 Apoptosis is the consequence of a series of precisely regulated events that are frequently altered in tumor cells, broadly categorized into two pathways, ie, the extrinsic pathway, which involves activation of the tumor necrosis factor (also known as the Fas death receptor family), and the intrinsic pathway, which involves the mitochondria.…”

Bioaccumulation of ZnO-NPs in Earthworm Eisenia fetida (Savigny)

“…As a well-known phytocatalyst, ZnO has received much attention in the degradation and complete mineralization of environmental pollutants [2][3][4]. ZnO-NPs are used in industrial products including cosmetics (sun screens, foot care, ointments and over-the-counter tropical products), pigments and coatings (ultra violet [UV]) protection, fungicide in paints), mouth washes, electronic devices and catalysts [5].…”