CrystEngComm Blog

Zinc oxide (ZnO) is an important semiconductor material which can be used for gas sensing.  The sensing property relies on an oxidation-reduction reaction on the ZnO surface between the detected gas and surface oxygen molecules which causes the resistance of the sensor to change.  The nature of exposed facets on the sensor is crucial to its performance however, control of the growth, number, and morphology of these features has so far proved difficult.

In their recent paper in CrystEngComm, Xiang, Xu and co-workers report a simple synthesis of ZnO which allows for exposed facet control.  They discovered a two-step hydrothermal synthesis does not require use of any templates or surfactants but achieves structure control simply by adjusting pH.  In this way, hexagonal-pyramids, -prisms, -prismoids and -disks could be formed (see below)/

The authors tested the materials for gaseous ethanol sensing and the sensitivity was found to vary in the order disks > prismoids > prisms > pyramids.  They showed that the sensitivity of the sensors increased with exposure of (0001) crystal planes as these polar facets can provide more active sites for oxygen absorption than other facets, increasing the gas sensor response.   Their new findings are significant for the future development of high performance gas sensors.

For more information, read the full paper:

Evolution of ZnO microstructures from hexagonal disk to prismoid, prism and pyramid and their crystal facet-dependent gas sensing properties
Nan Qin, Qun Xiang, Hongbin Zhao, Jincang Zhang and Jiaqiang Xu
CrystEngComm, 2014, DOI: 10.1039/C4CE00637B

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Gwenda Kyd has a PhD in metallocarborane chemistry from the University of Edinburgh. Other research work includes the spectroscopic study of the structure of glasses and organometallic electron-transfer reactions and the preparation of new inorganic phosphors. She has recently published a book on chemicals from plants.

Cheap and effective storage of renewable energy is a key challenge for consumers in the future. Lithium ion batteries (LIBs) are one class of materials that meet the important requirements of high energy density, low cost, good power capacity and efficient cycling.

Recent research on LIB materials has focused on maximising their favourable properties to bring them closer to commerical use.

A new paper by Jun Liu and co-workers (Central South University, Changsha, China) describes the preparation and testing of a new anode material based on MoO₃ and graphene oxide (GO). The former material is naturally abundant, has good chemical stability and a high storage capability but also exhibits poor conductivity and lithium ion diffusion. GO has good conductivity, a large surface area and is highly stable, making it an attractive material for composite material formation.  

The authors prepared the new material by first synthesising GO and α-MoO₃ nanoribbons before modifying the surface of the latter to produce a positive charge. This allowed the MoO₃ material to assemble onto the GO.  They then applied heat to form the product, α-MoO₃@GNS (GNS refers to graphene nanosheet), and fabricated the material to form an anode.

These robust nanocomposites exhibit greatly enhanced Li transport efficiency compared to other MoO₃-based materials, as well as high electrical conductivity and good cycling efficiency.

The authors concluded that the two components work synergistically to produce the observed properties and suggested the composite as a potential anode material for high performance LIBs.

 To find out more, read the full article:

Graphene nanosheets encapsulated α-MoO₃ nanoribbons with ultrahigh lithium ion storage properties
Pei-Jie Lu, Ming Lei and Jun Liu
CrystEngComm, 2014, DOI: 10.1039/C4CE00252K

Gwenda Kyd has a PhD in metallocarborane chemistry from the University of Edinburgh. Other research work includes the spectroscopic study of the structure of glasses and organometallic electron-transfer reactions and the preparation of new inorganic phosphors.  She has recently published a book on chemicals from plants.