On the enhancement of ethanol sensing by CuO modified SnO2 nanoparticles using fiber-optic sensor

Ethanol sensitivities of SnO2 and SnO2:CuO nanoparticles are studied using a clad-modified fiber-optic sensor. The sensing materials (SnO2 and SnO2:CuO) are structurally characterized by X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM) and their crystallite sizes are found to be 10 and 8-20 nm, respectively. The refractive indices of the sensing materials (nSnO2=2.438 and nSnO2:CuO=2.527) found from UV-vis analysis show that the fiber-optic sensor works under leaky mode operation. SnO2:CuO exhibits higher ethanol sensitivity compared to pure SnO2. It is found that the addition of CuO into SnO2 allows the effective formation of more number of oxygen vacancies, heterojunction, and high crystalline nanoparticles, which enhance its sensitivity to about three times than that of pure SnO2.