Novel CdSe nanorods/porous anodic alumina nanocomposite-based ethanol sensor: sensitivity enhancement by visible light illumination

In this present work, l-cysteine capped CdSe nanoparticles synthesized by a chemical route process were successfully embedded into porous anodic alumina (PAA) template via chemical bath deposition method. CdSe nanorods (NRs) were grown vertically on the PAA template via thermal annealing process at 350 °C under nitrogen. The morphological, structural, and optical properties of the prepared PAA and CdSe/PAA films were investigated in detail. The scanning electron microscopy exhibited the formation of CdSe NRs array with a pyramidal ends onto all sides of PAA matrix. Energy dispersive X-ray analysis confirmed that the prepared CdSe NRs/PAA are made of cadmium, selenium, and alumina materials. X-ray diffraction study revealed that the CdSe layer exhibit a hexagonal structure and the average crystallite size at about 9 nm. PL measurements showed green and bleu emissions peaks located at 2.05 eV and 2.7 that originate from the luminescent CdSe NRs and the oxygen defficiency centers formed in the PAA, respectively. CdSe NRs film on the PAA template was fabricated and employed as gas sensor for the detection of ethanol under visible-light illumination for 25–300 ppm at the optimum working temperature of 200 °C. Light illumination strongly enhance the sensor sensitivity. This effect has been discussed in term of light-matter interaction on the CdSe NRs surface. More hole are probably created which increase the conductance of the sensor and significantly improved the gas response