SnO2 is a broadly studied n-type semiconductor, which is of great interest for fabricating gas sensors. However, for some specific gas analytes, it is necessary to tune the morphology and modify the components of the SnO2 nanostructure to achieve the desired sensing performance. One of the challenges is to obtain a dense doping profile and get a large activated surface without promoting the serious aggregation of contact reactions during the sensing process.

As reported recently in the journal Nanotechnology, the Chinese group, which also includes scientists from the University of Science and Technology of China, has modified a coral-like SnO2/carbonaceous nanocomposite using plasma treatment (PT). The densities of hydroxyl and carboxyl groups on the nanocomposite were remarkably improved, which enabled the structure to adsorb a large quantity of indium ions and thereby enhanced the doping process.

The team used the as-prepared In-doped SnO2 nanostructures to fabricate a gas sensor for the detection of chlorobenzene. The researchers found that the sensor was selective and sensitive to chlorobenzene with a high response and low detection limit together with short response and recovery times.

The performance of the sensor based on In-doped SnO2 with PT was superior to test samples based on either In-doped SnO2 without PT or pure SnO2.

It is expected that the coral-like SnO2 nanostructures densely doped with indium could be a promising candidate for developing sensitive and selective gas sensors for environmental monitoring. But also, the group's results indicate that the plasma-assisted strategy could potentially be developed as a general method for densely doping a large variety of nanostructures for applications including Li-ion batteries, solar cells and catalysts.

The team is now developing novel nanostructures with improved properties for detecting environmental contaminants and purifying drinking water.