Hierarchically Porous ZnO Architectures for Gas Sensor Application

Abstract

Hierarchically three-dimensional (3D) porous ZnO architectures were synthesized by a template-free, economical hydrothermal method combined with subsequent calcination. First, a precursor of hierarchical basic zinc carbonate (BZC) nanostructures self-assembled by sheet-like blocks was prepared. Then calcination of the precursor produced hierarchically 3D porous ZnO architectures composed of interconnected ZnO nanosheets with high porosity resulting from the thermal decomposition of the precursor. The products were characterized by X-ray diffraction, Fourier tranform infrared spectroscopy, thermogravimetric-differential thermalgravimetric analysis, scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmett-Teller N 2 adsorption-desorption analyses. Control experiments with variations in solvent and reaction time respectively revealed that ethanol was responsible for the formation of the BZC precursor, and the self-assembly of BZC nanosheets into hierarchically 3D architectures was highly dependent on the reaction time. Gas sensing tests showed that these hierarchically porous ZnO architectures were highly promising for gas sensor applications, as the gas diffusion and mass transportation in sensing materials were significantly enhanced by their unique structures. Moreover, it is believed that this solution-based approach can be extended to fabricate other porous metal oxide materials with a unique morphology or shape.

Ambient Degradation of ZnO Powders: Does Surface Polarity Matter?

“…[8][9][10] The oxidation layer of ZnO that forms on a Zn metal surface can react readily with ambient CO 2 , moisture, and other airborne gaseous species. It is generally accepted that Zn corrosion involves surface dissolution of ZnO due to a thin surface water layer that is acidified by dissolved atmospheric CO 2 . This dissolution and carbonation sequence converts ZnO into Zn 5 (OH) 6 (CO 3 ) 2 (hydrozincite, abbreviated here as ZHC).…”

“…When ZnO is immersed in water, a soluble Zn(OH) 2 layer is formed on the particle surface via chemisorption or physisorption of hydroxyl. 6,7 The rate of ZnO dissolution is then controlled by equilibrium established between Zn(OH) 2(s) and species (e.g.…”

Drastic improvement in magnetization of CdO nanoparticles by Fe doping

“…In these materials, the presence of magnetic ions such as 3d (TM) and/or 4f (RE) ions leads to an exchange interaction between itinerary sp band electrons or holes and the d-electron spins localized at the magnetic ions, leads to versatile magnetic field-induced functionalities (Furdyna 1988). Recently, DMSs have fascinated researchers because of their potential applications in spin-based multifunctional electronic devices including spin field-effect transistors, optoelectronics, field emission devices, gas sensors, ultraviolet absorbers, quantum computer, and nonvolatile memory devices (Moezzi et al 2012;Chu et al 2009;Zhang et al 2009;Liu et al 2009;Neal et al 2006;Huang et al 2009). …”

Development of ZnO/Ag Nanocomposite Film for Gas Sensing Application

“…When the adding micrometer-scale and nanometer-scale building blocks in the 3D architectures help to induce and introduced a variety of novel properties including the structure features, specific surface area is higher and porosity and it will improve the accessibility of test gasses [8]. Recently, Zhang et al [9] and Lao et al [10] were improved the sensing properties of C2H2 through the synthesis of ZnO nanostructures at high temperature and it shows surface area is increased, mass transport is easier and stability is higher than other nanostructures. The aim of this work is to study the C2H2 sensing properties based on prepared ZnO/Ag nanocomposite.…”