Zinc oxide is an inorganic compound and considered as one of the most promising materials due to its direct wide bandgap and large exciton binding energy. One of its many properties is antibacterial property which is further enhanced through nanotechnology. This is because nanotechnology aims to exposed more number of constituents atoms along the surface of the material to make it more reactive which further enhances the property of the material. The antibacterial property of zinc oxide is largely dependent on particle size, morphology and surface defects which can be further improved through nanotechnology.
There are several techniques of incorporating zinc oxide nanomaterials to a substrate- hydrothermal method, ultrasonication, dipcoating, vapor-phase synthesis method, pulse laser deposition and microwave-assisted growth method. Most of them involved high temperatures and longer hours of synthesis which is unsuitable for thermolabile substrate such as paper. Ghule et al. (2006) reported incorporation of zinc oxide nanoparticles to paper through sonication, the need to control the growth and desired morphology is not achievable. Thus, there is a need to develop techniques to obtain the desired morphology.
One way to incorporate surface defects and manipulate morphology of a nanomaterial is through microwave irradiation technique. Microwave radiation provides intense friction and collision of molecules which greatly accelerates the nucleation. This rapid crystallization creates interstitial defects in the crystal which may serve as electron vacancies. This technique is cost-efficient and environmental-friendly making it suitable for large-scale production.