Increasing the reactive sites of ZnO nanoparticles by Li doping for ethanol sensing

Gas sensing in metal oxide semiconductors can be enhanced by creating more number of gas adsorption (reactive) sites. With this aim, Li-doped ZnO nanoparticles with chunk-shaped morphology is synthesized, which provide more adsorption sites due to its morphology and due to the presence of oxygen vacancies. XRD analysis of undoped and Li-doped (2 and 5 at.%) ZnO nanoparticles revealed the hexagonal wurtzite structure and SEM and TEM analyses showed the chunk-shaped morphology in all the samples. The presence of pores and voids between the nanoparticles in the chunk-shaped morphology plays a significant role in the gas sensing mechanism. PL analysis showed that compared to ZnO nanoparticles, Li-doped ZnO nanoparticles possess more number of oxygen vacancies, zinc interstitials, and Li interstitials, the important factors that enhance the sensitivity of Li-doped ZnO nanoparticles. As expected, Li-doped ZnO nanoparticles showed more sensitivity compared to undoped ZnO nanoparticles toward ethanol.