Using Cellulose as a Template for Zinc Oxide Formation

Nanocellulose is a renewable and abundant biomaterial that has been gathering a steadily increasing interest during the past decades. The potential of the material has mainly been attributed to its remarkable mechanical properties, low density and nanoscale dimensions, which has contributed to it to be seen as a promising material choice in biocomposites, foam materials and cellulose nanopapers.<br/>However, research focusing on using nanocellulose as a tool to control reactions is a topic which has been less highlighted as a potential application.<br/>Previous research has been particularly scarce when it comes to using aqueous nanocellulose dispersions during the synthesis of metallic oxides, especially when considering that properties of nanocellulose, such as dimensions, surface charge and functionalities can be accurately tuned, resulting in a highly varied behavior when dispersed in water as well as when interacting with ions.<br/>Zinc oxide (ZnO) is an inorganic oxide that can be synthesized by using mild, water-based synthesis protocols and is seen as a potential material choice in applications ranging from solar cells to antibacterial devices. However, previous research has shown that the properties of ZnO are heavily affected by the morphologies it forms, indicating that the ability to control the particle nucleation and growth is of paramount importance.<br/>Here, it is suggested that nanocellulose could be used as a versatile tool to tailor the morphology of inorganic oxides, such as ZnO, in order to either promote or suppress some of their inherent properties. Although it has been shown that cellulose can have some effects on the morphology of ZnO-particles, there are still not certain which aspects cellulose can affect when it comes to nucleation and growth of ZnO-particles. The incorporation of nanocellulose during the formation of inorganic particles, such as ZnO, also allows for the preparation of unique hybrid materials where the cellulosic material provides the structural properties and the tailored ZnO-particles provides the specific functional properties.<br/>The results in this study shows that the inclusion of bacterial cellulose into an aqueous synthesis protocol can both increase the yield as well as decreasing the particle size of ZnO, which indicates that cellulose can function as a nucleating agent during the formation of ZnO. It is additionally revealed that the presence of cellulose can alter the formation of nanostructures as hierarchical ZnO-particles are formed, which indicates that cellulose also can affect the growth mechanisms during the formation of ZnO.