A study carried out by a research group from Brazil, with collaboration from French and Spanish scientists, has reported, for the first time, gas detection properties in nanorods of silver tungstate in its alpha phase (α-Ag2WO4).The study showed that this material can be applied as a resistive sensor, displaying great performance when detecting ozone (O3). The work was and coordinated by Elson Longo, Professor at the São Paulo State University “Júlio de Mesquita Filho” (UNESP).

Resistive gas sensors are basically built from a material capable of changing its electrical properties when molecules of a certain gas are adsorbed in its surface. In the specific case of the silver tungstate, when it is submitted to an oxidant gas such as ozone, there is an increase in its electrical resistance that is proportional to the presence and concentration of the gas.

A new ozone sensor

In this work, the Brazilian scientists synthesized nanorods of silver tungstate and assembled a sensor based on such nanoparticles. They had put the sensor in a temperature controlled test chamber, exposed it to different concentrations of ozone gas, from 80 to 930 parts per billion (ppb), and evaluated its capacity to detect the ozone.

Present in high atmospheric layers, the ozone plays an important role protecting living beings by absorbing the solar ultraviolet radiation. The ozone is also used by people in several applications, such as, for example, cleaning water. However, the exposition to the gas in certain concentrations may lead to health issues as headache, burning and irritation in the eyes, and respiratory system problems. The World Health Organization (WHO) recommends avoiding the exposure to ozone gas above 120 ppb.

“Subjecting the compound to low amounts of ozone, we observed a fast response, as well as a very short recovering time, making its properties comparable or even better than traditional sensors as tin dioxide (SnO2), tungsten trioxide (WO3), and indium oxide (In2O3),” says Luís Fernando da Silva, first author of the article and postdoctoral fellow of the São Paulo Research Foundation (Fapesp) at UNESP’s Chemistry Institute of Araraquara.

This story is reprinted from material from Sociedade Brasileira de Pesquisa em Materiais (SBPMat), with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.