Simple Synthesis of Eco-Friendly Multifunctional Silk-Sericin Capped Zinc Oxide Nanorods and Their Potential for Fabrication of Hydrogen Sensors and UV Photodetectors

The present investigation describes a new eco-friendly, low cost material-based approach for sensor device fabrication. In this study, sericin capped zinc oxide nanorod (ZNR)-based H2 gas sensors and UV photodetectors were fabricated by incorporating silk-sericin with ZnO. The proposed sensors have higher sensitivity to H2 and greater photoresponsivity. The sericin capped ZNRs were fabricated from a degummed waste sericin solution using an inexpensive hydrothermal method. The sericin capped ZNRs show excellent H2 gas response (17.8%) and photoresponse with a fast response time under UV illumination due to sericin coating on the surface of the ZnO. Sericin is a water-soluble protein with strong polar groups as side chains, such as carboxyl, amino, and hydroxyl groups, which can easily interact with zinc particles through electrostatic interactions, resulting in the unique and improved ZnO sensor behavior. This interaction was characterized by various analytical techniques and compared with as-grown ZNR. The gas sensing property and UV photoresponse were evaluated for both as-grown ZNRs and sericin capped ZNRs as functions of the H2 concentration and time, respectively. Under 365 nm UV illumination, the sericin capped ZNR possesses an ultrahigh photoresponse of 408.4, which is 40 times better than that of the as-prepared ZnO devices (10.3). Moreover, the sensing response for the sericin capped ZNRs shows a complete recovery to the original level after evacuation of the H2 and UV illumination in each cycle, indicating complete desorption and decomposition of the main adsorbed moieties. The sericin capped ZNR presented in this work shows enhanced, sustained, and reversible H2 gas sensing and fast switching speed in the UV region and can be employed for the development of inorganic–organic novel materials utilizing the biomass from industrial waste.