ZnO nanoflowers modified with RuO₂ for enhancing acetone sensing performance

Surface modification is a simple and effective means to promote the sensing performance of metal oxide semiconductor-based gas sensors. Marigold-shaped ZnO nanoflowers are fabricated via a simple precipitation reaction and subsequently catalytically modified with RuO₂ on the surface through an ethylene glycol solvothermal treatment. The experimental results have proven that a very low content of Ru on the surface of ZnO exists in an oxidized state. However, the gas response of the sensor based on RuO₂-modified ZnO is remarkably improved by 17 times to 100 ppm acetone with the decrease of optimal operating temperature from 219 °C-172 °C and reduction in recovery time from 79-52 s. The sensing enhancement mechanism of surface modification can be attributed to the formation of massive small heterostructure between p-type RuO₂ ultrasmall nanoparticles and n-type ZnO as well as the catalytic effect of Ru⁴⁺ and a rougher surface.