Optoelectronic and Hydrogen Gas-Sensing Applications of Ultrasonically Fabricated ZnO-Au Nanoparticle-Decorated MWCNTs

Zinc oxide (ZnO)-based nanocomposites had been realized for promising photocatalytic and sensing applications. We have obtained multi-walled carbon nanotubes with a gold and ZnO (MWCNT/ZnO/Au) nanocomposite via ultrasonic assistance and studied them for photocatalytic degradation of methylene blue as well as for hydrogen gas sensing. Initially, the structural studies, conducted with x-ray diffraction (XRD) patterns of the specimens, indicated the hexagonal graphite crystal system of the MWCNT and a hexagonal wurtzite structure of ZnO existing in the nanocomposite. Transmission electron microscopy results indicated that the ZnO nanoparticles with an average size of 12 nm and 6-nm-sized gold nanoparticles formed on the surface of micrometer-sized long and 20-nm to 30-nm thick MWCNTs. UV-vis absorbance spectroscopic studies revealed the quantum confinement from the ZnO nanoparticles and plasmonically enhanced absorbance originating from the Au nanoparticles in the nanocomposite. Photoluminescence confirmed the inhibition of electron-hole pair recombination via the composite formation. Photocatalytic methylene blue degradation could achieved 99% efficacy with the MWCNT/ZnO/Au photocatalyst under a white light-emitting diode, and the tricomponent photocatalyst also showed better recyclability. Gas-sensing experiments conducted with the nanocomposite exhibited a low-temperature hydrogen gas sensitivity and showed the highest response at 200 degrees C with excellent selectivity for hydrogen gas sensing.

Automated summary

In this study, a gold and zinc oxide based nanocomposite (MWCNT/ZnO/Au) was synthesized using ultrasonic assistance and demonstrated excellent photocatalytic degradation and gas sensing performance.