CO Gas Sensing Properties of Pure and Cu-Incorporated SnO₂ Nanoparticles: A Study of Cu-Induced Modifications

Pure and copper (Cu)-incorporated tin oxide (SnO₂) pellet gas sensors with characteristics provoking gas sensitivity were fabricated and used for measuring carbon monoxide (CO) atmospheres. Non-spherical pure SnO₂ nano-structures were prepared by using urea as the precipitation agent. The resultant SnO₂ powders were ball milled and incorporated with a transition metal, Cu, via chemical synthesis method. The incorporation is confirmed by high-resolution transmission electron microscope (HRTEM) analysis. By utilizing Cu-incorporated SnO₂ pellets an increase in the CO sensitivity by an order of three, and a decrease in the response and recovery times by an order of two, were obtained. This improvement in the sensitivity is due to two factors that arise due to Cu incorporation: necks between the microparticles and stacking faults in the grains. These two factors increased the conductivity and oxygen adsorption, respectively, at the pellets' surface of SnO₂ which, in turn, raised the CO sensitivity.