Hollow cylindrical ternary ZnO/Co3O4/CuO nanocomposite thick film on inter-digitated electrodes for selective ammonia gas sensing

In this work, the hollow cylindrical (ZnO)(x)((Co3O4)(2)CuO)(1-x )(x = 1, 0.9, 0.8 and 0.7) nanocomposites coded as ZCC0, ZCC10, ZCC20 and ZCC30 were synthesized using the sol-gel co-precipitation method. The prepared samples were coated on the inter-digitated electrodes using the doctor blade method which makes the sensor highly integrable with the electronic circuits. The samples were characterized using XRD, FESEM, UV-vis-NIR spectroscopy, XPS, EDX mapping, BET, and FTIR. Hollow cylindrical microstructure was observed for the sample using scanning electron microscopy along with a surface rich in oxygen vacancies and adsorbed oxygen species which was confirmed by EDX and XPS analysis collectively. The prepared samples were tested for gas sensing applications. The sensor (ZnO)(x)((Co3O4)(2)CuO)(1-)x for (x = 0.8) shows highest response among other samples. A good response of 14.18 was obtained for ammonia as the model gas and atmospheric air as a reference gas. The response time and recovery time of the sensor was 25 s and 8 s respectively. The results clearly state that the synthesized sensor is very promising for the gas sensing devices fabrication.