Morphologically-dependent photocatalytic and gas sensing application of Dy-doped ZnO nanoparticles

Nowadays, growing populations and advanced industrialization has led to increase the problems related to water and air pollution. Herein, a rapid synthesis of Dy-doped ZnO nanoparticles is being reported through a facile and rapid solution combustion method. The synthesized nanoparticles were characterized by various techniques in term of their structural, morphological, optical, photocatalytic and gas sensing properties. The detailed characterization of the Dy doped ZnO nanoparticles confirmed the excellent crystallinity and optoelectronic properties. Herein, pure ZnO, different concentrations of Dy (2.0 at.wt%, 3.0 at.wt%, 4.0 at.wt%) were used as dopants (DZ1-DZ-3). It has been observed that the extent of Dy doping greatly influenced the morphological, structural, and band gap properties. The morphology of synthesized revealed its -leaf-shaped morphology high surface area to volume ratio and are well crystalline. Typical grain size of Dy-ZnO nanoparticles were found to be in the range of 47–77 nm. Further, the prepared Dy doped ZnO nanoparticles were used as photocatalyst for the photodegradation of DR-31 dye. Complete photodegradation of DR-31 dye was observed within 60 min of UV light irradiation. Kinetic studied reveals that all the Dy doped ZnO nanoparticle follow first order kinetics. The value of pseudo first order constant were found to be maximum 0.02925 (min)⁻¹ for DZ-3. In order to develop smart and functional nanoscale sensor device for ethanol sensing, the prepared Dy doped ZnO nanoparticles were coated onto the surface of a glass substrate by spin coating technique. As fabricated sensors shows excellent sensing performance, even for a very low concentration of 25 ppm of ethanol, with the response in the range of 20–27%. Maximum sensitivity were found at an operating temperature of 150 °C. It is noteworthy that morphology of the nanoparticles of the sensitive layer is maintained after different concentration of Dy. Higher surface to volume ratio of the Dy doped ZnO nanoparticles were responsible for gas sensing and photocatalytic applications. The optimized concentration for DR-31 dye photodegradation and ethanol gas sensing applications were 4.0 at.wt% of Dy-ZnO nanoparticles. - Highlights: • Dysprosium doped ZnO nanoparticles were synthesized by simple combustion method. • Different concentrations of Dy (2.0%, 3.0%, 4.0%) were used as dopants. • 4.0% of Dy- ZnO exhibited complete photodegradation of DR-31 dye. • Photocatalytic activities for all the samples were observed in 60 min. • Maximum gas response was obtained for DZ-3 at 150 °C.