Changes in the crystal structure of SnO2 nanoparticles and improved H2S gas-sensing characteristics by Al doping

Pristine and Al-doped SnO2 nanoparticles with different amounts of Al dopant were synthesized using a conventional hydrothermal process. The existing SnO2 exhibited simple interstitial physical bonding (SnO2-Al (1:0.16)) with the Al dopant; however, with an increase in the Al concentration, the bonding changed to substitutional chemical bonding (SnO2-Al (1:0.33)). We found that this crystal structural change is strongly interrelated with surface reactivity; the optimized Al-doped SnO2 nanoparticles-based sensor exhibited a significantly improved response of 17.38 - 20 ppm H2S gas with a response time of 35 s. The enhanced gas response was related to the high surface area of the optimal gas sensor (BET surface area = 78.087 m3/g) as well as the beneficial effects of Al doping. It is highlighted that this simple technique of engineering the bonding characteristics can be widely applied to other semiconducting metal oxides.

Automated summary

The crystal structural change of Al-doped SnO2 nanoparticles affects the gas response of the sensor significantly. By optimizing the bonding characteristics and surface area, the sensor shows a greatly improved response to H2S gas. This technique has the potential for application in other semiconducting metal oxides.