A feasible strategy to balance the crystallinity and specific surface area of metal oxide nanocrystals

Abstract

Practical, efficient synthesis of metal oxide nanocrystals with good crystallinity and high specific surface area by a modified polymer-network gel method is demonstrated, taking ZnO nanocrystals as an example. A novel stepwise heat treatment yields significant improvement in crystal quality. Such nanophase materials can effectively degrade common organic dyes under solar radiation and can perform very well in photo-assisted detection of NO2 gas. Other typical metal oxide nanocrystals with good crystallinity and high specific surface area were also synthesized successfully under similar conditions. This work provides a general strategy for the synthesis of metal oxide nanocrystals, balancing the crystallinity and specific surface area.

Enhancing visible light-activated NO2 sensing properties of Au NPs decorated ZnO nanorods by localized surface plasmon resonance and oxygen vacancies

“…A spin-orbit splitting of 23.1 eV is consistent with that of photoelectrons excited from Zn 2+ atoms in the ZnO crystal lattice [21,22]. The weakening Zn 2p XPS peak and its slight chemical shift toward high binding energy with increasing Au content (i.e., an increase in HAuCl 4 concentration) indicate the deficiency of O atoms [23]. In high resolution Au 4 f XPS spectra ( figure 3(c)), the Au 4 f peaks of Au NPs [21].…”

Oxygen Vacancy-Mediated ZnO Nanoparticle Photocatalyst for Degradation of Methylene Blue

“…The UV emission is attributed to the direct recombination of free excitons [5]. The blue-green (470 nm) emission implies that electrons trapped by the oxygen vacancies recombine with photo-generated holes [5,29]. This further confirms the existence of oxygen defects on the surface of the ZnO photocatalyst.…”

“…Figure 6 shows the room temperature PL spectrum of different ZnO NPs, where the pristine and vacuum-treated ZnO both display strong UV and weak visible emission peaks, at 384 and 470 nm, respectively. The UV emission is attributed to the direct recombination of free excitons [5]. The blue-green (470 nm) emission implies that electrons trapped by the oxygen vacancies recombine with photo-generated holes [5,29].…”

“…It is a common contaminant in wastewater released from industrial (e.g., textile) dyeing processes, which is toxic to human health. All the photocatalysis experiments were carried out in a customized photocatalytic reactor, with a 250 W GYZ (HWL-125, Osram Lighting Co., Ltd., Berlin, Germany) as the UV light source (λ ≤ 365 nm), as shown in our previous work [5]. In a typical experiment, 50 mg each of Sample A and Sample B were dispersed, respectively, into 100 mL of MB aqueous solution (4 mg/L), in 250 mL glass beakers.…”

Cellulose Nanocrystal–ZnO Nanohybrids for Controlling Photocatalytic Activity and UV Protection in Cosmetic Formulation

“… 28 , 40 Here, the role of the nanotemplate of the mesoporous MFCNC becomes important, as it confines the growth of ZnO because of the high specific surface provided by the MFCNC (212.8 m 2 g –1 ), 19 where the surface area for ZnO NPs in the wurtzite phase is approximately 29.35 m 2 g –1 . 43 This phenomenon has three related consequences, namely; (1) it controls the NP growth, (2) it increases the specific surface area of the semiconductor ZnO, and (3) it effectively prevents e – /h + recombination and increases the concentration of the photoinduced charge carriers at the surface of the catalyst, which has major implications for the photocatalytic performance of the structure. A schematic illustration of a proposed mechanism, with explanation of the redox reactions is described in Figure 7 .…”