Anhui Polytechnic University

About: Anhui Polytechnic University is a education organization based out in Wuhu, China. It is known for research contribution in the topics: Control theory & Microstructure. The organization has 2966 authors who have published 2381 publications receiving 21586 citations. The organization is also known as: Anhui Mechanical University & Wuhu Mechanical School.

Metal Oxide Nanostructures and Their Gas Sensing Properties: A Review

Abstract: Metal oxide gas sensors are predominant solid-state gas detecting devices for domestic, commercial and industrial applications, which have many advantages such as low cost, easy production, and compact size However, the performance of such sensors is significantly influenced by the morphology and structure of sensing materials, resulting in a great obstacle for gas sensors based on bulk materials or dense films to achieve highly-sensitive properties Lots of metal oxide nanostructures have been developed to improve the gas sensing properties such as sensitivity, selectivity, response speed, and so on Here, we provide a brief overview of metal oxide nanostructures and their gas sensing properties from the aspects of particle size, morphology and doping When the particle size of metal oxide is close to or less than double thickness of the space-charge layer, the sensitivity of the sensor will increase remarkably, which would be called "small size effect", yet small size of metal oxide nanoparticles will be compactly sintered together during the film coating process which is disadvantage for gas diffusion in them In view of those reasons, nanostructures with many kinds of shapes such as porous nanotubes, porous nanospheres and so on have been investigated, that not only possessed large surface area and relatively mass reactive sites, but also formed relatively loose film structures which is an advantage for gas diffusion Besides, doping is also an effective method to decrease particle size and improve gas sensing properties Therefore, the gas sensing properties of metal oxide nanostructures assembled by nanoparticles are reviewed in this article The effect of doping is also summarized and finally the perspectives of metal oxide gas sensor are given

High-Yield Synthesis of Ultralong and Ultrathin Zn2GeO4 Nanoribbons toward Improved Photocatalytic Reduction of CO2 into Renewable Hydrocarbon Fuel

Abstract: Single-crystalline Zn2GeO4 nanobelts with lengths of hundreds of micrometers, thicknesses as small as ∼7 nm, and aspect ratios of up to 10 000 were synthesized in a binary ethylenediamine/water solvent system using a solvothermal route. The ultralong and ultrathin geometry of the Zn2GeO4 nanoribbon proves to greatly promote the photocatalytic activity toward reduction of CO2 into renewable hydrocarbon fuel (CH4) in the presence of water vapor.

Robust Hollow Spheres Consisting of Alternating Titania Nanosheets and Graphene Nanosheets with High Photocatalytic Activity for CO2 Conversion into Renewable Fuels

Abstract: Robust hollow spheres consisting of molecular-scale alternating titania (Ti0.91O2) nanosheets and graphene (G) nanosheets are successfully fabricated by a layer-by-layer assembly technique with polymer beads as sacrificial templates using a microwave irradiation technique to simultaneously remove the template and reduce graphene oxide into graphene. The molecular scale, 2D contact of Ti0.91O2 nanosheets and G nanosheets in the hollow spheres is distinctly different from the prevenient G-based TiO2 nanocomposites prepared by simple integration of TiO2 and G nanosheets. The nine times increase of the photocatalytic activity of G-Ti0.91O2 hollow spheres relative to commercial P25 TiO2 is confirmed with photoreduction of CO2 into renewable fuels (CO and CH4). The large enhancement in the photocatalytic activity benefits from: 1) the ultrathin nature of Ti0.91O2 nanosheets allowing charge carriers to move rapidly onto the surface to participate in the photoreduction reaction; 2) the sufficiently compact stacking of ultrathin Ti0.91O2 nanosheets with G nanosheets allowing the photogenerated electron to transfer fast from the Ti0.91O2 nanosheets to G to enhance lifetime of the charge carriers; and 3) the hollow structure potentially acting as a photon trap-well to allow the multiscattering of incident light for the enhancement of light absorption.

Ultrathin, Single-Crystal WO3 Nanosheets by Two-Dimensional Oriented Attachment toward Enhanced Photocatalystic Reduction of CO2 into Hydrocarbon Fuels under Visible Light

Abstract: An ultrathin, single-crystal WO3 nanosheet of ∼4–5 nm in thickness, corresponding to six repeating unit cells of monoclinic WO3 along the c axis, was synthesized with laterally oriented attachment of tiny WO3 nanocrystals formed using a solid–liquid phase arc discharge route in an aqueous solution. Size-quantization effects in this ultrathin nanostructure alter the WO3 band gap to enable the nanosheet to exhibit enhanced performance for photocatalytic reduction of CO2 in the presence of water in hydrocarbon fuels that do not exist in its bulk form.

ZIF-8/Zn2GeO4 nanorods with an enhanced CO2 adsorption property in an aqueous medium for photocatalytic synthesis of liquid fuel

Abstract: The photoreduction of CO2 on inorganic semiconductors has been researched for several decades, but the conversion efficiency is still low due to the recombination of photo-generated electron–hole pairs, low utilization efficiency of solar energy and weak adsorption of CO2. Here we for the first time demonstrate that metal–organic frameworks such as ZIF-8 can effectively adsorb CO2 dissolved in water, and promote photocatalytic activity of a semiconductor catalyst in CO2 reduction into liquid fuels in an aqueous medium. In particular, Zn2GeO4/ZIF-8 hybrid nanorods were successfully synthesized by growing ZIF-8 nanoparticles on Zn2GeO4 nanorods. The Zn2GeO4/ZIF-8 nanocomposite inherits both high CO2 adsorption capacity of ZIF-8 nanoparticles and high crystallinity of Zn2GeO4 nanorods. The Zn2GeO4/ZIF-8 hybrid nanorods containing 25 wt% ZIF-8 exhibit 3.8 times higher dissolved CO2 adsorption capacity than the bare Zn2GeO4 nanorods, resulting in a 62% enhancement in photocatalytic conversion of CO2 into liquid CH3OH fuel. The strategy reported here is promising for developing more active photocatalysts for improving CO2 conversion efficiency by taking advantage of excellent adsorption property of metal–organic frameworks in aqueous media.