ZnO–Cellulose Composite for UV Sensing

A novel method to fabricate a composite material made by compressing Zinc Oxide (ZnO) crystals and cellulose fibers is reported. The fabricated material shows electrical photoconductivity changes when exposed to ultraviolet (UV) light. Mixing cellulose fibers with ZnO yields a higher photosensitivity than the one obtained from devices mainly made of ZnO. The structural, electrical, and photosensitivity tests are performed for these mixtures with the goal to determine the mechanisms enhancing their sensitivity as well as finding an optimal ZnO-cellulose composition for the fabrication of sensors. A device made from a mixed 50-50 wt% composition of ZnO and cellulose yields the best sensitivity to UV, suggesting that the enhancement could be because of the higher oxygen permeability of the cellulose matrix facilitating the O₂ adsorption-desorption processes on the ZnO surface.