Synthesis, characterization and low temperature carbon monoxide sensing performance of alkaline earth metal incorporated tin oxide

Abstract

Since from the onset of industrial revolution which brought tremendous changes in the life style of every individual in this planet a major concern regarding these changes to make more sustainable in near future has started to rise. Due to rapid use of renewable energy resources for technological developments induced significant amount of harmful pollutants in the atmosphere. These pollutants are not only harmful for the environment but also prove very much fatal to all human beings. These pollutants include some gases for ex. CO, CO2 etc and different volatile organic compounds for ex. ethylene, benzene, formaldehyde etc. Among all these gases the thing which makes carbon monoxide one of the most fatal gases is due it its colorless and odorless behavior. As the atmospheric pollution has started to rise at an alarming rate in recent years, detection of these harmful and flammable gases are the subjects of growing interest for researchers worldwide. Detection of this gas is very important for pollution control, protection of individuals as well as environment. Scientist and researchers worldwide are working on several mechanisms through which gases can be detected for ex. infrared spectroscopy, mass spectroscopy, semiconductor gas sensors and others. Among these metal oxide semiconductor based gas sensors are at higher advantage because of their low fabrication cost, easy availability, wide variation of detectable target gases etc. Along with advantages there are also certain disadvantages associated with metal oxide semiconductor sensors for example, high response time, low cross sensitivity etc. Therefore in order to overcome certain disadvantages associated with these sensors we have to either select the most appropriate material for the sensing of any particular target gas or we have use some noble techniques by which we can enhance the properties of any metal oxide ready to make it suitable for gas sensing. In this quest of finding a proper semiconductor material for carbon monoxide sensing at an ambient temperature in this present work we have first synthesized sol gel based nanocrystalline pristine SnO2 for sensing purpose. The preliminary result shows that sensitivity of SnO2 based gas sensor is not very high at ambient temperature. Then in order to improve sensing performance of SnO2 gas sensors we have chose to incorporate alkaline earth metal ions(Ca2+,Ba2+,Sr2+ )in tin oxide matrix and detailed sensing performance was studied. The primary reason of incorporation is to improve the surface characteristics of SnO2 by creating more lattice sites for oxygen adsorption which can enhance the sensing of the metal oxide.