Abstract
Porous ZnO sheets containing various degrees of a nanoscaled pore were successfully synthesized using a simple hydrothermal method and various postannealing procedures. The porosity features of the ZnO sheets can be easily tuned by changing both the annealing temperature and annealing atmosphere. The dense porous nature of ZnO sheets is beneficial to enhance light absorption. Moreover, the substantially increased oxygen vacancies in the ZnO sheets were observed especially after the hydrogen treatment as revealed in the X-ray photoelectron spectroscope and photoluminescence analyses. The high density of surface crystal defect enhanced the photoinduced electron-hole separation rate of the ZnO sheets, which is crucial for an improved photoactivity. The porous ZnO sheets formed at a hydrogen atmosphere exhibited superior photoactive performance than the porous ZnO sheets formed at the high-temperature ambient air annealing. The dense pores and massive crystal defects formed by a hydrogen atmosphere annealing in the ZnO crystals might account for the observed photoactive behaviors in this study.
Highlights
Two dimensional (2D) sheet- or plate-like metal oxides for scientific applications attract much attention recently due to their unique physical and chemical properties [1,2,3,4]
The ZnO sheets have an uneven surface feature. This might be associated with the crystalline ZnO sheet comes from the 300 ◦C postannealed as-grown hydrothermally derived two-dimensional sheet-like Zn4CO3 (OH)6·H2O. Such a thermal annealing procedure might engender the surface contractile change of the Zn4CO3 (OH)6·H2O, and a rugged surface feature was formed on the crystalline ZnO sheets
Compared with the sheet morphology of the ZnO-A in Figure 1c,d, the ZnO-H sheets in Figure 1e,f exhibited smaller and denser pores in the sheets. Considering their high porosity, these as-synthesized porous ZnO sheet structures are highly favorable to be applied in light absorption and a high surface area
Summary
Two dimensional (2D) sheet- or plate-like metal oxides for scientific applications attract much attention recently due to their unique physical and chemical properties [1,2,3,4]. The 2D sheet- or plate-like oxide nanomaterials are beneficial in increasing the light interaction area in the oxides and are promising in photoactive device applications. The excellent solar-driven photocatalytic hydrogen evolution has been observed for the mesoporous black anatase TiO2 nanosheets synthesized via a biotemplate method combined with an ethanediamine encircling process [6]. Chemical bath derived porous 2D β-Bi2O3 nanoplates show excellent photoinduced current density and have potential in the application of photoelectron catalysis [7]. For photocatalytic applications, both faces of 2D sheets and pores can be in contact with the target pollutant solution, favoring the sufficient utilization of the catalytic surface. The aforementioned examples demonstrate that the 2D oxide nanostructures fabricated with a suitable pore number and size in them can further successfully enhance the photoactive performance of these 2D oxide nanomaterials
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
