Novel single-crystalline ZnO nanosheets with porous structure have been fabricated by annealing ZnS(en)(0.5) (en = ethylenediamine) complex precursor. The morphology and structure observations performed by field emission scanning electronic microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) indicate that numerous mesopores with a diameter of about 26.1 nm distribute all through each nanosheet with a high density. The transformation of structure and composition of samples obtained during thermal treatment processes were investigated by x-ray diffraction (XRD), x-ray photoelectron spectrometry (XPS), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) absorption spectroscopy. The formation mechanism of the porous structure is proposed. For indoor air contaminant detection in which formaldehyde and ammonia are employed as target gases, the as-prepared ZnO nanosheets were applied for the fabrication of gas sensors. It was found that the as-fabricated sensors not only exhibit highly sensitive performance, e.g., high gas-sensing responses, short response and recovery time, but also possess significant long-term stability. It is indicated that these ZnO nanostructures could promisingly be applied in electronic devices for environmental evaluation.

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A unique coral-like porous SnO(2) hollow architecture with enhanced photovoltaic property for dye-sensitized solar cell application was prepared, and a biomimetic swallowing growth mechanism for the formation of the special structure was also proposed for the first time.

Porous tin oxide (SnO2) nanotubes were prepared by using multiwalled carbon nanotubes as templates. The morphology and crystal structure of the SnO2 nanotubes were characterized by field emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The SnO2 crystallite size was about 5 to7 nm. The as-prepared porous SnO2 nanotubes exhibited a good response and reversibility to some organic gas, such as ethanol and acetone. The sensor responses to 100 ppm ethanol and acetone were 130 and 126, respectively, at a working temperature of 200 °C. In addition, the sensors also exhibited a good response to methanol, propanol, 2-propanol, ethyl acetate, and ethyl ether. The relationship between the gas-sensing properties and the microstructure of the as-prepared SnO2 nanotubes was also discussed.

Hollow and porous In(2)O(3) nanospheres have been prepared by the hydrolysis of InCl(3) using carbonaceous spheres as templates in combination with calcination. Based on the observation of scanning electronic microscopy (SEM) and transmission electron microscopy (TEM), it has been revealed that the as-prepared In(2)O(3) nanospheres have a uniform diameter of around 200 nm and hollow structures with thin shells of about 30 nm consisting of numerous nanocrystals and nanopores. Owing to the hollow and porous structures, In(2)O(3) nanospheres possessing more active surface area exhibit a good response and reversibility to some organic gases such as methanol, alcohol, acetone and ethyl ether. In addition, the response mechanism of hollow and porous In(2)O(3) nanospheres to organic gases has been proposed. Furthermore, these prepared In(2)O(3) spheres showed a UV-visible absorption peak centered at around 309 nm, and their photoluminescence spectra have also been investigated.

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