Solution precursor dependent sensing characteristics of ZnO coatings developed via SPPS process

Zinc oxide (ZnO) coatings were developed using aqueous solutions of zinc nitrate and zinc acetate as starting precursors via solution precursor plasma spraying (SPPS) and gas and UV-detection properties were studied. Phase analysis confirmed the formation of polycrystalline ZnO having wurtzite structure when using both precursors. The microstructures of the coatings were investigated with respect to the precursors used. Relatively porous coatings were obtained when using acetate than the nitrate precursor which was highly due to the different chemical routes of ZnO formation for each precursor droplet upon contact with plasma jet. ZnO coatings were found to be sensitive towards carbon dioxide (CO₂) analyte gas but do not show any good recovery which was attributed to the microstructure of the coatings. Moreover, the sprayed ZnO coatings showed good sensitivity and recovery towards UV light. These findings showed the feasibility of SPPS process for the fabrication of finely-structured ZnO coatings that can be used as UV sensor but needs to be enhanced further for to function well as gas sensor.